MEMCAL LEIEMA1&Y ANATOMY FOR NURSES A TEXTBOOK OF ANATOMY FOE NURSES BY WILLIAM GAY CHRISTIAN, M.D., Professor of Anatomy, Medical College of Virginia, Richmond. WITH THIETY-FOUE OEIGINAL ILLUSTBATIONS, FIVE OF WHICH AEE IN COLOES ST. LOUIS C. V. MOSBY COMPANY 1917 K*,- COPYRIGHT, 1917, BY C. V. MOSBY COMPANY F r f f r e ; Press of Company Q.M 6 DEDICATED TO THE MEMORY OF EDITH CAVELL WHO DIED FOR HER FRIENDS 5664 PREFACE I have written this book because I have found the existing textbooks on the subject unsatisfactory. I believe pupil nurses should be shown the various tis- sues and organs of the body and that this work should be done before they enter hospitals for their profes- sional training. This can be readily accomplished if the medical colleges will offer a brief, practical course in anatomy during the vacation. Such a course should occupy not more than three or four weeks. From two to three hours a day of laboratory instruction, using prepared dissections, might be profitably employed. I fear that I may have made the book too elaborate, but teachers can readily omit descriptions given in too much detail. The illustrations have been drawn by Miss Helen Lorraine from specially prepared dissections, and ap- pear to me exceptionally well done. They are in many instances designedly diagrammatic. W. G. C. Medical College of Virginia, Richmond, Va. CONTENTS CHAPTER I INTRODUCTION CHAPTER II OSTEOLOGY - 2l CHAPTER III A.RTHROLOGY ^ CHAPTER IV MYOLOGY 6 ' CHAPTER V SPLANCHNOLOGY 9( CHAPTER VI ARTERIES AND VEINS 107 CHAPTER VII THE NERVOUS SYSTEM 140 CHAPTER VIII ORGANS OF THE SENSES 169 CHAPTER IX HISTOLOGY ILLUSTRATIONS FIG. PAGE 1. Profile of skeleton 21 2. Typical vertebra, view from side 24 3. Typical vertebra, view from above 25 4. Front view of skull 46 5. Base of skull, upper surface 48 6. Base of skull, lower surface 49 7. Pelvic ligaments and capsule of hip ....... 65 8. Muscles. Front of neck, trunk, and upper extremity . 69 9. Orbital muscles 76 10. Muscles. Back of trunk, upper extremity, and hips . . 78 11. Front view of organs. Semi-diagrammatic 95 12. Diagram of entire circulation 110 13. The aorta and its branches 114 14. Superior mesenteric artery 116 15. Diagram of arteries and veins of upper extremity. . . 126 16. Diagram of arterial circulation in lower extremity . . 130 17. Brain, lateral view 143 18. Brain, mesial view 145 19. Larynx, anterior view 180 20. Larynx, inside view 182 21. Simple tissues 188 22. Human cartilage cells 191 23. Hyaline cartilage 191 24. White nbrocartilage 193 25. Elastic cartilage 194 13 14 ILLUSTRATIONS FIG. PAGE 26. Nucleated bone cells, etc. 195 27. Transverse section of compact tissue of bone greatly magnified 196 28. Section parallel to the surface from the shaft of the femur 197 29. Vertical section of human spleen low power .... 205 30. Cross section of pancreatic tubule 206 31. Portion of transverse section of human liver .... 208 32. Injected lacteal vessels in two villi of human intestine 212 33. Diagrammatic representation of the course of the urinif- erous tubules and the kidney vessels . . . . . . 214 34. Diagram of the ending of a bronchial tube .... 217 ANATOMY FOR NURSES ANATOMY FOR NURSES CHAPTER I INTRODUCTION The only knowledge of anatomy which is perma- nently retained is that which is seen or felt. Names are comparatively unimportant, but must be employed to prevent confusion, to enable one to impart w r hat is known and to facilitate such studies as physiology, pathology and surgery. Certain terms, frequently em- ployed, must be explained and comprehended before the study can even be begun. The entire body is conceived of as a cube, and hence would have six faces which would be directed up- ward, downward, forward, backward and to either side. The first four are easy of comprehension; but the two lateral confuse us because there are two arms and two legs, distinguished as right and left, each itself having two surfaces w r hich cannot receive these familiar names, because the right side of the left arm has all the peculiarities of the left side of the right; and there must be a name for this symmetrical appear- ance. Hence, the body may be considered as split by an imaginary plane drawn from the middle of the top of the head down between the feet. Such an imagi- nary plane or line would add a face which would be directed toward the midline and would be called the 17 18 ANATOMY FOR NURSES mesial or inner face. The mesial or inner faces of the arms or legs are exactly alike, while the parts which are. directed away from, the midline are the lateral or outer faces and are also alike. Practically all anatomical names were given when Latin or Greek were the only languages in which learning was concealed. The names which are here employed and which have the great convenience of being intelligible to anatomists all over the world, are of Latin or Greek origin. These names are em- ployed in surgical and medical works, as well as in anatomy. Such terms as front, back, etc., are not usually used, but words of Latin origin with the same significance as follows: Upward is superior, downward is inferior, forward is anterior, backward is posterior, inward is medial, and outward is lateral. So far only the faces of a cube which have one definite direction have been considered, while some of the cube may be turned to face partly in two directions. These oblique portions are designated by compound w r ords indicative of the tw r o directions in- volved, thus: Antero-superior would be facing forward and upward; antero-median, forward and inward; an- tero-lateral, forward and outward, etc. If a pencil is placed upright on a table, point up- ward, the pencil will be a line at right angles to the plane of the table, and its point will be in the direc- tion in which the table top faces ; i. e., it is the superior surface of the table. The names for many appear- ances in the body may be determined in just that way. Put the part, ab6ve for instance, in its ana- tomical position, and then place a pencil on the various INTRODUCTION 19 parts of the bone just as on the table. If properly placed, the pencil will point in one of the six cardinal directions or to some angle between two or more of them. This Avill be the direction of that part and probably a portion of its name. The anatomical position is not the natural posi- tion of the body. If one stands at ease he will find that the arms swing at the sides with the thumbs nearly on the thighs, the fingers partly bent and the toes turned out a little. Now turn the hands until the little fingers touch the thighs, thumbs outward, fingers straight, heels and big toes touching, head up and eyes looking straight in front. This is the ana- tomical position. In it every portion of the body must be placed before it can be properly studied, and in it one must, in imagination, place every person and part of a person, until the mind unconsciously perceives them only in that awkward attitude. Only the broad faces of the cube have thus far been considered. It has, however, narrow lines, or borders, and sharp points, or angles, separating these faces. In anatomical language the faces are surfaces, the lines borders, the points angles, spines or processes. It is chiefly in the study of the bones and viscera that these terms are employed. Other technical terms will be explained as they occur. CHAPTER II OSTEOLOGY The bones form the framework of the body. They are somewhat more than two hundred in number and vary greatly in size and function. Those of the ex- tremities are chiefly a set of levers, actuated by mus- cles and bound together by ligaments, the entire ap- paratus being designed for support and to produce motion of some sort. Others serve to more or less perfectly surround cavities which contain important organs, while their exterior faces give firm points of attachment to muscles and ligaments. Roughly bones may be divided into two classes by the presence or absence of marrow cavities: those having such cavi- ties are called long; and those without the cavities, ir- regular bones. The irregular bones consist more or less completely of two plates or tables bound together by numerous minute bands of bone with spaces be- tween, forming a network not unlike sponge. Both varieties are covered by a delicate membrane, the per- iosteum, which contains a large number of blood ves- sels and is the tissue to which ligaments and muscles are really attached. The long bones are found chiefly in the extremities, while most of the irregular bones are in the skull and spinal column, though the hands and feet each contain several bones of this variety. The term extremity is applied to what is usually called arm and leg. In anatomical language the up- 20 OSTEOLOGY 21 Skull Cervical vertebrae Scapula Scapula Lumbar vertebrae v Pelvis . ,~r Femur Fig. 1. Profile of skeleton. ANATOMY FOR NURSES per extremity comprises all the structures from the tips of the fingers to the attachment of the collar bone to the breast bone, while the lower extremity extends from the toes to the pelvis, including the hips. The upper is divided into shoulder, arm, forearm, and hand; the lower into hip, thigh, leg and foot. The term arm, therefore, is correctly used only for that portion of the upper extremity extending from the shoulder to the elbow; while leg is that part from knee to ankle. The remaining portions of the body comprise the head, neck, and trunk, the neck insensibly blending with the upper, and the trunk, or body, with the lower ex- tremity. THE VERTEBRAL, OR SPINAL, COLUMN The spinal, or vertebral column, binds the head to the neck, forms the middle and posterior part of the lat- ter and of the trunk, and finally binds the trunk to the extremities and the two lower extremities to each other. It contains a central canal for the spinal cord and is so important that it is properly the first object of our study. At an early period of life it consisted of thirty-three pieces of bone called vertebrae (from a Latin word meaning to turn, because turning or twist- ing the body from side to side is accomplished at the joints between these bones) ; but, in adult life, nine of these pieces have fused together in such a way as to constitute two pieces, so that the total number of vertebrae is now twenty-six. Of^these, seven are found in the neck and are called cervical : twelve form the posterior wall of the cavity containing the heart and lungs, thoracic cavity, and are called thoracic verte- OSTEOLOGY 23 brae for that reason, dorsal because they form a large part of the back; five are found in the " small of the back" and are called lumbar, or abdominal from form- ing the middle of the posterior wall of the abdominal cavity. The remaining two, sacrum and coccyx, are in the pelvis and are called the pelvic vertebrae. A Typical Vertebra With certain important exceptions, every vertebra consists of a large central hole (foramen, opening), the vertebral foramen, surrounded Tby a solid mass of bone in front called the body, two short rounded pro- jections running backward one from either side of the body, the pedicles, which terminate in flattened, broad sheets of bone which run backward and inward until they meet, the laminae, whose union forms a projection of varying size, shape and direction, the spine, or spi- nous process. In addition to these appearances there are four projections, two running upward and two downward, by which the vertebrae are joined together, known as 'articular processes, because the joints, or articulations, formed by their union permit move- ment, and are distinguished as superior and inferior; and two lateral projections, one on either side, form- ing levers to which muscles can be attached by which the vertebra may be moved. These processes are called transverse firom their direction. Above and below each pedicle is a notch, intervertebral, which becomes an intervertebral foramen when two vertebrae are ar- ticula^ted, to transmit the spinal nerves. In the several regions of the column the component parts of the vertebrae differ sufficiently to enable us 24 ANATOMY FOR NURSES to distinguish a vertebra of one region from that of another. In the cervical region the body is small, has a pro- jecting lip on either side above and a notch in front. Below it has a notch on either side and a lip in front. In the thoracic region the ~body has no lips, is nearly Sup. articular process Transverse process Inf. articular process Spinous process Fig. 2. Typical vertebra, view from side. round, and has either a whole or a half facet (articular surface) for the head of a rib. In the lumbar region the body has neither facet nor lips. Except that they increase in size from above downward, the pedicles have little to distinguish them. The lamince are large in proportion to the size of the bone in the cervical and thoracic regions and occupy less of the bone in the lumbar. OSTEOLOGY 25 The spines are short and forked (bifurcated) in the cervical region ; long, triangular, pointed, and run nearly downward in the thoracic; and short quadrilateral, and very large in the lumbar. Body Pedicle ' Sup. articular process df*' *r^ Lamina ^B Spinous Transverse process Spinous process Fig. 3. Typical vertebra, view from above. The superior articular processes look upward and backward in the cervical, backward in the thoracic, and inward in the lumbar region. The inferior look down- 26 ANATOMY FOR NURSES ward and forward in the cervical, forward in the tho- racic, and outward in the lumbar. The transverse process is perforated by the vertebral foramen at its base and bifurcated at its extremity in the cervical region; runs outward and backward, is club-shaped and bears an articular facet in the thoracic, and is sharp, curved, and rib-like in the lumbar. Peculiar Vertebra The first cervical is called the atlas and has no body. Its spinal foramen is very large. It has five articular processes of which the first is on the pos- terior face of its anterior part, called the anterior arch. The two superior are oval, longer from before backward than from side to side and look upward. They are receiving surfaces for a condyle. The in- ferior look downward and are flat and circular. The bone has no spine, Avhich would interfere with the movements of the head if present, and is the connect- ing link between the skull and spinal column. The second cervical is called the axis. It is pecu- liar on its upper and typical on its lower aspect. It is the transition vertebra. On its body above is a sharp pointed process, called odontoid because it is like a tooth, whose anterior face is articular for the similar facet on the back of the front part of the atlas. This upright piece is a pivot or axle around which the atlas revolves in turning the head from side to side. The superior articular processes look upward and are round. The spine is very large and bifurcated below. OSTEOLOGY 27 THE SACRUM AND COCCYX As the coccyx is often ossified to the sacrum and is always articulated with it so that the two act nearly as one bone, they may be described together. The sacrum forms a double wedge whose apex is prolonged downward by the coccyx to a sharp point, while its base is directed upward to the body of the fifth lumbar vertebra whose under surface it ex- actly resembles. Its anterior surface is concave from side to side and from above downward, so as to in- crease the capacity of the pelvic cavity, whose pos- terior wall it forms. It has on either side of the mid- line a vertical row of loramina, which are circular and smooth and terminate" laterally in shallow grooves. The posterior surface, much narrower than the an- terior, is convex in both directions. It shows a row of tubercles in the midline, the rudiments of spinous processes, and two rows of foramina smaller and less regular than those on the front. On each side the bone is wide above, narrow and rough below. Near the front above is an articular facet, shaped somewhat like an ear and called auri- cular. This is to articulate with a similar facet on the ilium. THE RIBS AND THORAX The bony wall of the chest or thorax is made up oi the breast bone, or sternum, on the midline in front, and the front of the dorsal vertebrae behind with twelve ribs on each side. The sternum consisted at one time of numerous 28 ANATOMY FOR NURSES pieces, as the sacrum did, which have coalesced into three called, from above downward, manubrium, gladiolus, and ensiform cartilage. It may conveniently be de- scribed as a single bone, large above, where it has at each corner, or angle, a saddle-shaped articular facet for the collar bone (clavicle), which is the only bony link between the trunk and the upper extremity, and tapering to an irregular point below. It is slightly convex in front and concave behind. Each lateral border presents pits for the reception of the cartilages which bind the seven true ribs to the sternum. The ribs, twelve on each side, are much curved long bones known by number from above downward. The first seven articulate with the vertebral column and the sternum, and are hence known as vertebro-sternal. The next three are indirectly held to the sternum through attachment to the cartilage of the seventh, and have received the name of vertebro-cliondral; while the last two are attached to the vertebral column alone and are called vertebral. A typical rib, like a typical vertebra, possesses certain characteristics common to all though varying in degree. Each has a posterior or verte- bral, and an /Anterior, or sternal, extremity and a shaft with two surfaces and two borders. On the vertebral ex- tremity there is a head with two articular facets, sepa- rated by a transverse ridge, for the two vertebrae and the intervertebral disk with which a rib articulates, a neck and a tubercle. The latter is also marked by a facet for the transverse process of the lower of the two verte- brae with which it articulates. The posterior part of the rib runs nearly outward, until beyond the tubercle, when it turns abruptly forward and downward, mak- OSTEOLOGY 29 ing the bone curved in two directions; i. e., it is con- cave inward and less concave upward, or curved around a vertical and a horizontal axis. The anterior extremity is blunt and has a rather deep pit for the cartilage which binds it to the sternum. The shaft has a round upper and a sharp lower bor- der. Its outer surface, which is convex, is rough while the inner is concave, smooth, and marked near the lower border by a groove running three-fourths the length of the bone. Where the double curvature occurs, there is a ridge marking the angle of the bone. The first rib is the most peculiar and important. It has only one facet on its head ; its surfaces look nearly upward and downward and its borders inward and out- ward. On its upper surface are two grooves, separated by a slight ridge, for the subclavian artery and vein. Other ribs are also called peculiar, but only the elev- enth and twelfth need be noted. They are called false or floating ribs because they are fastened at but one end. Each has a single articular facet and no pit for a sternal cartilage. The twelfth is the guide to the kidney. The Thorax The chest or thorax is a cone opened at the top with its base downward. The projection forward of the thoracic verterbrae makes a cross section of the cone heart-shaped. As the ribs increase in length from the first to the seventh and their anterior extremities are lower than the posterior, while the sternum is shorter than the thoracic part of the column, it follows that the chest is deeper behind than in front, and wider at 30 ANATOMY FOR NURSES the bottom than at the top. The inclination of the ribs has an important bearing on the movements of the chest in breathing. The spaces between the ribs are called intercostal and are filled by soft tissue. THE EXTREMITIES The skeleton of the upper extremity consists of the scapula and clavicle forming the shoulder girdle; the humerus, the single bone of the arm; the radius and ulna of the forearm and numerous bones of the hand. That of the lower extremity consists of the os innomina- tum (nameless bone) forming the pelvic girdle; the femur, the single bone of the thigh; the tibia and fibula of the leg, and numerous bones of the foot. The Shoulder Girdle The clavicle or collar bone is a long bone and, like all bones of that class, has a shaft and two extremities, inner or sternal and outer or acromial. It runs al- most horizontally outward from the upper end of the sternum to the acromioii process of the scapula. The inner extremity is rounded and marked by a saddle-shaped (that is concavo-convex) articular facet; the outer, flattened from above downward and marked by an oblong facet which faces outward and downward so as to rest on the acromion. The shaft is prismoid for its inner two-thirds and flat for its outer one-third. It is convex forward for its inner two-thirds and concave forward for the outer third. The inferior face is marked by a depression, called rhomboid, where it is fastened to the first rib, OSTEOLOGY 31 and a shallow groove, running outward, called subcla- vian. The upper face and anterior border are rounded, slightly rough and can be made out by the finger, ex- cept in the very fat, or are subcutaneous. The Scapula. This is an irregular, flat triangular bone, forming the posterior and bulkier part of the shoulder girdle. It has anterior and posterior faces; external, internal, and superior borders; superior, in- ferior, and external angles, a spine, acromion and cora- coid processes. The anterior face has one large hollow for lodging a muscle, while the posterior has two, the smaller above and the larger below the spine. . These hollows are known respectively as the sub scapular, supraspinous and infraspinous fossce. k*V^- C\A-iJc_ The internal or vertebral border is long, thin, and lipped. The superior is short, thin, and has a notch near its outer end. The (mtew&f or axillary is thick and rough, giving attachment to several muscles. The superior and inferior angles give attachment to muscles; but the external bears a pear-shaped articu- lar cavity, the cjlenoid^ which receives the humerus and with it forms the shoulder joint. The large end of the cavity is below and it is very shallow. The spine starts near the vertebral border and, ris- ing rapidly above the level of the bone, terminates in a triangular projection, the ncromion process, which overhangs the glenoid cavity and protects the shoul- der joint from violence directed from above and be- hind. The surfaces of the spine, looking upward and downward, form the floor of the supraspinous and roof 32 ANATOMY FOR NURSES of the infraspinous fossa. The posterior border of the spine is thick, rough, and subcutaneous. The acromion process has on its inner border the articular facet for the clavicle. The Qoracoid process lies under the outer third of the clavicle, projecting like a crooked finger over the glenoid cavity from its upper inner aspect. The Pelvic Girdle The Os Innominatum. The innominate or nameless bone, consisted, in fetal life, of three bones called ilium, ischium, and pubis, which are united in the ace- tabulum. The ilium is the, expanded upper part of the bone presenting an external surface which sup/ports the great muscles of the hip and a smaller imernm surface, also lodging muscles, and having the important func- tion of forming a large part of the false pelvis. Sur- mounting the top of the bone is a sinuous crest which reaches its highest point about the junction of its an- terior and middle thirds. This erect can n ^e felt, ex- cept in the very fat, but is not subcutaneous. Many important structures are located 1,^ reference to the crest, whose extremities are called & ^v^M*^and posterior- superior spinous processes. Below each point is a smaller and less important process designated inferior spinous process anterior and posterior. The ischium, by the greater part of its outer face, forms three-fifths of the acetabulum, while its inner face forms nearly all of the lateral wall of the pelvis, notably its inclined plane. The posterior face is the back of the acetabulum. The lower part of the ischium OSTEOLOGY 33 is called its tuberosity, upon which the weight of the body rest when one sits straight. The slender anterior piece of bone running 1 up from the tuberosity and form- ing part of the boundary of the tkyvmd or obturator foramen, is called the ramus of the ischium. The pubis forms the most anterior, internal and least massive part of the bone. Its outer end is the innermost part of the acetabulum, its inner, which is rough and ir- regular, forms the union between the two innominate bones (symphysis pubis). The posterior face is the an- terior wall of the pelvis, while the anterior, somewhat rough, gives attachment to several muscles. Its superior border is broad and rounded and marked near the inner end by a prominent spine which is one of the most important points of departure in measure- ments around the hip joint, pelvis and abdomen. The lower border is an oblique groove which forms the upper boundary of the thyroid foramen. Q /^ ~JL c\/x*^r^ d*~ The acetabulum (a vessel for holding vinegar) is analogous to the glenoid cavity of the scapula, but much deeper. Its bottom is a nonarticular notch and the lower inner part of the prominent rim is wanting. The articular part is the interior of the rim. The obturator foramen is somewhat triangular, more so in women than in men, and is found between the body of the pubis above, that of the ischium externally jc^ TVl and the rami of the two internally. ^^^wjJA THE PELVIS The deep cavity formed by the ossa innominate, sacrum and coccyx is the pelvis. The expanded flank 34 ANATOMY FOR NURSES bones, or ilia seem to stop at a prominent ridge or line below which the pelvis, or deep basin, suddenly contracts. This line, extending along the top of the pubis, across the ilium and on to the sacrum, is called the ileo-pectineal.Q,. All that lies above it is the false and all below the true pelvis. The true pelvis is deepest behind and on the sides and very shallow in front. The posterior wall is the hollow of the sacrum, the lateral Avails the inclined plane or inner face of the ischium, while the front is formed by the union of the pubic bones. The opening from the abdomen, marked off by the ileo-pectineal line, is called the inlet; the lower, irregu- lar opening, is the outlet, because the child in being born enters from above and passes out, or is born through the lower opening. It will be seen that the inlet is a dense ring of firmly united bones, while the outlet is made up of three deep notches, anterior and two lateral, with a flexible joint between sacrum and coccyx in the middle behind. The female pelvis is much more ca- pacious than the male, is not so deep but wider, and the pubic arch is particularly wide. The pelvic girdle binds the lower extremities to the trunk as the shoulder girdle does the upper. The former is designed to support the weight of the body, the lat- ter to carry out a great variety of movements. The first is designed primarily for strength, the latter for grace and freedom. Hence it will be observed that the shoulder girdle is given all the strength consistent with perfect freedom of movement, w^hile the pelvic girdle has all the freedom of movement consistent with great strength. OSTEOLOGY 35 HUMERUS AND FEMUR These bones have many features in common which should be compared. Both are long bones and, of course, each has a shaft and two extremities. The Humerus The upper extremity of the humerus has a nearly hemispherical head which looks upward, inward and backward, separated from the remainder of the bone by a circular -groove called the anatomical neck. Ex- - tergal to this are two tuberosities, internal or JLesser and external or greater, separated by a deep vertical groove, the Mcipital. Below the tuberosities the up- per extremity diminsh.es to the circumference of the shaft, this portion being called the surgical neck. The lower extremity is flattened and much wider from before backward than from side to side. A little above the termination of the, bone a projection on each side, improperly called al^cbndyle, inner and outer, presents strong subcutaneous attachments for muscles of the forearm. The inner of these tuberosities is much larger than the outer, while of the ridges leading upward from the condyles, the outer is the more promi- nent. The remainder of this extremity shows a rounded articular surface ( capitulum humeri) for the radius outwardly and a trochlear surface for the sig- moid cavity of the ulna inwardly. A trochlea is a pulley; i. e., a depression with a ridge on each side, like the grooved wheel in which a sash cord runs. A deep depression behind and a shallow one in front, above the trochlea, receive the olecranon and cora- 36 ANATOMY FOR NURSES uoid processes of the ulna in extension and flexion, respectively, and bear the names olecranon and cora- noid fossae. The shaft is somewhat three sided in the middle, cir- cular above, and nearjy flat below. The bicipital groove expands into the kwier race; the outer has a rough im- pression for the deltoid muscle about half way down, while both posterior and outer are furrowed by a groove, the musculo-spiral which lodges a nerve of that name. The_rMg$s bounding the bicipital groove are called internal or anterior and external bicipital ridges. The Femur The nearly spherical head of the femur is set on an oblique constricted projection of bone which corre- sponds to the anatomical neck of the humerus. This is called the neck of the femnr and so supports the round head as to make it face upward, inward, and forward. The head has a little nonarticular depres- sion near its center. The neck is shorter above than below and is flattened from before backward. Ex- ternally the neck terminates at a quadrilateral tu- berosity called the great trochanter (meaning to turn) which projects above the neck, gives attach- ment to many muscles and is an important landmark about the hip, easily felt though not subcutaneous. Below and internal to the greater is a sharply promi- nent lesser trochanter. The two are connected by lines or ridges called intertrochanteric. The lower extremity is much larger than the upper. A rough prominence on each side is called a tuberosity, OSTEOLOGY 37 *JM L/VuJ? mteiial and external, while the bottom is occupied by two oblong, oval, convex articular projections called eondyles. These are separated behind by a deep 11011- articular notch, the intercondyloid, and united in front by a trochlear surface for the patella. The extremity is somewhat flattened. The shaft is bowed so as to be convex forward. It is so nearly cylindrical that borders are nearly indistin- guishable except the posterior, called linea aspera (rough line) which gives attachment to a large number of mus- cles. It breaks up below into two lines which divide to bound a triangle called popliteal. Above the linea aspera runs to the trochanters m three divisions. The femur is much larger than the humerus, its head more globular, its anatomical neck longer, all points showing it is designed for power and not mobility. THE RADIUS The radius is the outer and smaller of the two bones of the forearm and increases in size from above down- ward. The upper extremity has a head consisting of a sau- cer-like cavity for the radial head of the humerus, surrounded by and continuous with an articular rim for the lesser sigmoid cavity of the ulna. Below this is a constricted necjc, the smallest part of the bone and below and ijalegstal to this a tuberosity, the bicipital, rough behind and smooth in front. The lower extremity has two .> articular cavities. The lowest is triangular, base ^ftwjjrf c6ncave in both di- rections, while that on the inner side is longest from ANATOMY FOR NURSES before bacKward and is a mere articular strip. The lowest is the carpal, the inner the sigmoid cavity. Ex- ternally the bone terminates in a blunt point, the sty- loid process, easily felt and an important landmark at the wrist. The back of the lower extremity is marked by grooves, separated by ridges, for the passage of tendons. The shaft is distinctly three sided with one sharp border, the mtcrnal or interosseous, where the mem- brane which binds it to the ulna is attached. The outer surface is rough and convex. The anterior has an oblique line across its upper third. THE ULNA The ulna, the large internal bone, decreases in size from above downward. The upper extremity is made up of two processes, o^ecranon above and coranoid below, which form, an- teriorly, a receiving surface for a trochlea, the great sigmoid cavity, that is a central ridge with a groove on each side, to fit the trochlea of the humerus. Each process terminates in a point which fits into the cor- responding fossa of the humerus. The back of the olecranon is rough and subcutaneous. The outer face of the coranoid has a small cavity, the lesser sigmoid, continuous with the greater, for the rim of the ra- dius. The lower extremity consists of two processes. The one at the inner back part is a blunt point, the styloid process, which is subcutaneous and the most promi- nent landmark of the wrist. The outer elevation, sep- OSTEOLOGY 39 arated from the styloid by a groove, is articular below and around its circumference. The rim fits into the sigmoid cavity of the radius, while a cartilage sepa- rates the lower face from the carpus. The shaft, for its upper two thirds, is very triangular, showing a prominent posterior border, subcutaneous throughout, a sharp thin external or interosseous and an indistinct anterior border. The anterior and pos- terior faces are the best marked for muscular attach- ment. THE PATE The patella is a sesamoid bone developed in the tender of the triceps exfenlfjf of the leg. Its posterior surface corresponds to the anterior of the olecranon process ; i. e., is the receiving surface for a trochlea. The large end of the bone is above and it terminates in a blunt point below. The anterior face is rough and ridged. The bone is in fact the olecranon process of the tibia. THE TIBIA The tibia, is the internal, and many times the larger, bone of the leg and the only one entering into the knee joint The upper extremity presents an inner and an outer tuberosity, the outer showing a facet for the fibula and the inner a groove for a tendon, aupportmguic glciioid ^- cavities for the enndyles of the femur. The inner cav- ity is oval and deeper than the outer, which is circular. Between the two is a short, thick bifurcated jywne^ Be- 40 ANATOMY FOR NURSES low the cavities in front is the anterior tubercle of the tibia, rough below and smooth above. The lower extremity is quadrilateral, but is prolonged downward on its anner face into an irregular process \ . > '- - * , called the internal malleolus, whose inner face is rough and subcutaneous and forms an important landmark of the foot and ankle opposite the malleolus there is a rough triangular depression for the fibula. The summit of the bone, articular and concave, a little wider in front than behind is called the tarsal cavity and receives the astragalus. The shaft, like that of the ulna tapers from above downward and is three sideid. Its anterior border, crest or shin, and its tmumal surface are both sub- cutaneous and much exposed to injury. The pos- terior face begins above in a triangle, base up, the pop- liteal, which is marked off by a ridge of the same name. Below it is narrower and less well marked. This surface is notable for carrying the largest of the nutrient foramina. The outer border is interos- seous. THE FIBULA The upper extremity of the fibula is nearly globular, presenting a round articular facet ittieiiw&iyi and a rough, subcutaneous, nonarticular knob externally. The lower extremity has a pear-shaped articular surface, a part of the ankle, internally and externally the sub- cutaneous rough face of the (vdcrjwl inaUcolns, as im- portant a landmark as the internal. The shaft, like the entire bone, is very slender. It fits opposite the tibia and is bound to it at each end OSTEOLOGY 41 like the pin to a broach. It is so twisted that its bor- ders and surfaces change places from above down- ward. Its chief function seems to be to support the outer side of the ankle. THE HAND The Carpus, Metacarpus, and Phalanges The carpus is made up of eight irregular bones ar- ranged in two rows, the upper of Avhich forms the wrist joint while the lower presents a set of irregular articular facets for the metacarpus: First row, scaph- oid, semilunar, cuneiform, pisiform ; second row T , tra- pezium, trapezoid, os magnum, unciform. The car- pus is convex and rough on its dorsal surface and con- cave and rough on its palmar face. Above it presents a condyle, long diameter from side to side and convex in both directions. Inferiorly the most external facet is saddle-shaped for the metacarpal bone of the thumb while the facets for the remaining metacarpal bones are less regular in outline and show less freedom of movement, The metacarpus is made up of five long bones known numerically from the outer side. They vary in appearance, the first, that of the thumb being short, thick and marked by a saddle-shaped facet above, that of the index finger, the second, being the longest, the third having a styloid process at its upper outer angle, the fourth none of these appearances, and the fifth being articular on only one side. The lower or distal extremity of each terminates in a rounded head com- 42 ANATOMY FOR NURSES pressed from side to side, which is as large as, or larger than, the upper extremity. The shaft is concave anteriorly and laterally and convex posteriorly. The phalanges are fourteen long bones arranged in columns of three for each finger except the thumb. The one which articulates with a metacarpal bone is called a first or proximal phalanx, the next the second, and the last the third or distal. The upper extremity of a first phalanx has a cup- like cavity for the head of a metacarpal bone. The lower extremity shows a trochlea. The second phalanges would show a receiving surface for a trochlea above and a trochlea below; while the third has a re- ceiving surface for a trochlea above, and below termi- nates in an irregular rough surface which supports the nail behind and the pulp of the finger in front. The shaft is convex posteriorly and concave anteriorly and decreases in length for each row. THE FOOT The Tarsus, Metatarsus, and Phalanges The tarsus consists of seven irregular bones arranged in two rows from behind forward: os calcis and astra- galus in the first row; scaphoid, cuboid and three, in- ternal, middle and external, cuneiform bones in the second. The os calcis, or heel bone, longer than the others, projects backward to form a lever on the bottom of which the weight of the body largely rests and which is used for raising that weight in walking. Above it OSTEOLOGY 43 has two articular facets, separated by a groove, the sulcus calcanei, for the astragalus. Below it and on each side it is rough and nonarticular, the outer side convex, the inner concave and the lower marked by anterior and posterior tubercles. In front there is a concavo-convex articular surface for the cuboid. , The astragalus, a nearly square bone, has five articu- lar faces, three of which are continuous. The upper face is convex from before backward, wider in front than behind, continuous with the lateral articular facets which, w r ith it, form a blunt wedge fitting into a sort of mortise formed by the tibia and fibula. The facet for the latter is pear-shaped, large end below, and much larger than that for the tibia. In front of the upper facet is a constricted neck. The anterior ex- tremity is an articular head for the scaphoid. The lower surface is divided into a large, posterior, con- cave, and a small anterior convex facet for the os calcis, separated by a groove called sulcus tali, which forms, with the sulcus calcanei, the sinus tarsi when the bones are articulated. The thin posterior extremity is marked by an oblique groove. The cuboid is wedged in between other bones, hav- ing the os calcis behind, fourth and fifth metatarsals in front, and the scaphoid and external cuneiform to its inner side. Its lower face has a deep groove and a prominent ridge, both called peroneal, the outer end of which can be felt about the middle of the outer side of the foot. Its upper surface is rough; its posterior sur- face projects partly under the os calcis. There are two articular surfaces on its anterior extremity and usually but one on its inner face. 44 ANATOMY FOR NURSES The scaphoid, supposed to be boat-shaped, is con- cave posteriorly for the astragalus, convex and marked by three wedge-shaped facets in front for the cuneiform bones, and rough and convex on its remain- ing aspects. Internally it terminates in a blunt tuber- osity, forming an important landmark on the inner face of the foot. The three cuneiform bones are known from within outward as first, second, and third ; or internal, middle, and external. They are all wedge-shaped but the first, which is the largest and less regularly so than the others. The first also has its large end downward while the others have the longest side upward. The first can be felt on the inner side of the foot and it and the other two on top. Behind they all articulate with the scaphoid while in front each supports a metatarsal bone, the internal the first, the middle the second and the external the third. All touch the second. The metatarsal bones, like the metacarpal, are five in number and are named numerically from the inner side. They resemble the similar bones of the hand but can be distinguished from them by the facts that the shafts taper from back to front and the head or distal end is much smaller than the base. The first metatarsal is much larger than the first metacarpal and has a concave facet instead of concavo-convex on its proximal end. The phalanges are also like those of the hand in number and general arrangement, but differ from them in having shafts so short that they form mere con- necting links between the articular extremities. The foot, as a whole, is concave on its lower or OSTEOLOGY 45 plantar aspect both from side to side and from before backward, forming an arch which makes the chief weight rest on the posterior tuberosities of the os calcis and the ball of the big toe. THE HYOID The hyoid is a small but most important bone lying in the neck. The base of the tongue, the larynx, and pharynx are fastened to it. It is shaped something like a horseshoe, but the toe or front of the shoe is thick and strong, forming the body of the bone, while the slender heels stick out behind like horns. If the neck is grasped, just above the Adam's apple, between the thumb and index finger the outline of the body and horns can be easily discerned. THE SKELETON OF THE HEAD The head is rather arbitrarily divided into the cra- nium or upper part, and the face, or front. There is no sharp line of demarcation between the two. There are eight bones in the head and fourteen in the face. Those of the head are occipital at the back, frontal in front, a parietal on each side connecting the first two, a tem- poral on each side connecting the top and base which is formed by the ethmoid and sphenoid with parts of the frontal and occipital. In the face two superior maxillary, two malar, two nasal and one inferior maxillary form the visible bones which can be felt in the living being, while a lachry- mal in each orbit, a palate, forming the back part of the nose and mouth,. an inferior turbinate in each nos- 46 ANATOMY FOR NURSES j. 4. Front view of skull. OSTEOLOGY 47 tril and a vomer betAveen the nostrils complete the number. The top of the skull is made up of the frontal, the two parietal s, and part of the occipital. Where the occipital and the parietals should meet, an opening is found in the newborn called the posterior fontanelle and a similar space is found at the junction of the parietals and frontal, the anterior fontanelle. The face show T s the sloping frontal bone above and below the eye sockets (orbits) one on each side of the projecting nose, formed by the nasal and nasal pro- cesses of the superior maxillary bones. Below the nose comes the opening of the mouth, containing thirty-two teeth, if all are present, whose roof is formed in front by the horizontal part of the upper maxilla and be- hind by a similar process of the palate, and front and sides by the lower jaw but whose floor is wanting. On each side of the nose, at a little distance from it, is the prominence formed by the cheek or malar bones, leading along a subcutaneous ridge, the zygomatic arch, to the temporal bone just in front of the external auditory meatus, the most important appearance on the lateral aspect of the skull. A large depression in front of this opening is the temporal fossa. The su- perior maxilla, next to the largest bone of the face, is hollow and its cavity, the antrum of Highmore, com- municates with the nasal cavity, so that disease may readily extend from nose to antrum. The nasal cavity has a part of its roof formed by a sieve-like piece of the ethmoid, so there is a very thin wall between the nose and the brain cavity. The inner wall of each nasal cavity is flat and formed chiefly by the vomer. 48 ANATOMY FOR NURSES The outer wall has three projecting shelves of bone (the turbinates) striking- into it, so that this wall is very irregular and complex. The orbits are two four sided pyramids laid flat, whose apices point inward and backward and whose nearly circular bases open on the face. The apex of each is formed by the optic foramen, through which the nerve of sight passes from the cranium to the orbit. The sides of the pyramid are known as roof, floor, inner and outer walls. The inner wall is made of very thin bone separating the orbit from the nasal cavity and skull, with both of which it communicates. The opening into the nose is the canal for the nasal duct, by which the excess of tears is carried into the nose to moisten respired air. The inferior maxilla is the only bone of the face with articular surfaces. It is U-shaped and turned up at the back to form two rami which terminate in a condyle behind, and a coronoid process, for muscular attachment, in front. The body has sockets for sixteen teeth. If the top of the skull be sawed off so as to expose the interior, the under surface of the vertex, or upper wall, and the upper surface of the base can be seen. The interior of the skull is marked by numerous fur- rows spreading, like limbs, chiefly from a hole in the sphenoid by which the chief artery for the skull and its membranes enters. There are, besides, broader but shallower depressions, separated by slight ridges, which lodge the convolution and sulci of the brain. A large straight groove runs from the front to a projection called anterior occipital protuberance at the back, -10 [11 -12 Fig. 5. Base of skull, upper surface. 1, Anterior fossa; 2, Middle fossa; 3, Posterior fossa; 4, Cribriform plate; 5, Ootic foramen; 6, Foramen rotundum; 7, Mid. lacerated foramen and carotid canal; 8, Foramen spino- sum; 9, Internal auditory meatus; 10, Eminence of semicircular canal; 11, Jugular foramen; 12, Foramen magnum. 50 ANATOMY FOR NURSES 1 Fig. 6. Base of skull, lower surface. OSTEOLOGY 51 which lodges a chief element in the venous circulation. This is joined at right angles on the occipital bone by similar and deeper grooves. These lodge what are called the longitudinal and lateral sinuses. The upper surface of the base of the skull is divided into three spaces, each lower than the preceding, known as anterior, middle and posterior fossae of the skull. The anterior is formed mainly by the horizontal part of the frontal and the ethmoid, the middle by the body and great wings of the sphenoid and the temporal, while the posterior is chiefly formed by the occipital, but has contributions from the temporal. Each fossa lodges a corresponding part of the brain and each has openings through which the cranial nerves find exit from, and blood vessels entrance to, the skull. In the midde fossa a bulge on the petrous part of the temporal shows the proximity of the ear to the brain, from which it is sepa- rated by a thin shell of bone. The anterior fossa shows openings for the first nerve and the optic fora- men for the second. The middle fossa has the anterior lacerated foramen and the foramen rotundum; the pos- terior, the foramen magnum and the jugular foramen. The lower surface of the base shows the roof of the mouth, ending in the hard palate behind, just above which are the posterior nares. Behind this is the basilar process of the occipital and, behind that, the foramen magnum with a condyle on either side. Laterally are seen the foramen ovale, the opening for the entrance of the carotid artery and the jugular foramen for the trans- mission of numerous nerves and the jugular vein. CHAPTER III ARTHROLOGY Arthrology is the study of the joints, more par- ticularly of those which are movable. When bones are united by interlocking processes of bone, as in the skull, the joint is called a synartkrosis. These are immovable joints. When the union is by fibrous tissue separating the bones and permitting movement only by twisting the fibers, it is called amphiarthrosis or slightly movable joints, as between the bodies of the vertebrae. When two smooth articular surfaces are bound to- gether by ligaments, usually exterior to the joint, it is a diarthrosis or freely movable joint. Every joint belongs to one of the three classes. Synarthrodial joints are con- fined to the skull; amphiarthrodial to the vertebral col- umn, pelvis, hand, and foot. The other joints are diar- throdial. DIARTHRODIAL ARTICULATIONS Of these there are six varieties: Arthrodial, formed by flat surfaces with very slight motion often in many directions. Example: That be- tween articular processes of vertebrae. Ginglymoid, hinge or trochlear, where motion occurs freely but in only two directions. Example: Elbow, knee. Condyloid, formed by a condyle and a proper receiv- 52 ARTHROLOGY 53 ing cavity. Example: Wrist, occipital condyles, and cavities of atlas. Saddle-shaped, or concavo-convex, or joints by recipro- cal reception. Example: Sternoclavicular. Pivot, or trochoid, when one bone revolves around another. Example: There are but two, atloaxoid and radioulnar. Ball and socket, or enarthrodial, when a cup-like cav- ity receives a rounded head. Example: There are but two, shoulder and hip. The movements of which joints are capable appear innumerable, but are really limited to eight. Gliding, most marked in arthrodial joints, where it is the only movement, but present in all diarthrodia. Flexion, movement usually forward but sometimes backward. Extension, the reverse of flexion. Abduction, movement away from a midline, usually that of the body. Adduction, movement toward a midline. These are called the four angular movements and when performed in succession, in any order, produce the sixth movement called Circumduction, which may be inward or outward. Revolution, where one bone revolves around another. It occurs only in pivot joints. Rotation occurs only at the shoulder and hip and is made by turning the arm or thigh inward or outward around an axis drawn from the center of the head of the bone to the internal tuberosity at the lower end. 54 ANATOMY FOR NURSES ARTICULATIONS OF THE VERTEBRAL COLUMN The vertebrae articulate by their bodies and articular processes and have ligaments binding other parts which do not touch. The joint between the bodies is an am- phiarthrosis effected by a disk of fibrocartilage which performs the triple function of binding the bones to- gether, lengthening the column and furnishing a cush- ion between each pair of bones to lessen shock. Move- ment can take place by twisting the fibers, or by com- pressing the disk on one side while it is stretched on the other. Running the length of the column both on the front and back of the bodies is a b.undl? of fibers forming the anterior and posterior oSiSmen ligaments of the spine. That on the front is the stronger. That on the back runs in the spinal canal. Ligaments are also found between spines and attached to their points, called interspinous and supraspinous. Capsular liga- ments surround the articular processes. As the atlas has no body, there is no intervertebral disk between the first and second cervical vertebras. A very strong band is attached to the inner face of each lateral mass and encircles the odontoid process, forming the transverse ligament. Capsular ligaments surround the articular processes and a continuation of the anterior common ligament passes to a tubercle on the front of the atlas. The odontoid process has a diverging bundle running from near its summit to the margin of the foramen mag- num on each side. These are the check ligaments because they prevent too much turning of the head. A part of the posterior comiAon ligament extends from the body ARTHROLOGY 55 of the axis over the odontoid process to the anterior margin of the foramen magnum. The atlas is held to the occipital bone by capsular ligaments around the anterior processes, by thin mem- branes running from the anterior and posterior arches to the corresponding margins of the foramen magnum and by a continuation of the anterior common from the tubercle of the atlas to the occipital in front of the fora- men magnum. Throughout the column the numerous and powerful muscles of the back are powerful means of binding the bones together. The ligaments binding the last lumbar vertebra to the sacrum are practically identical with those between the lumbar vertebrae. A capsular ligament is a bag made of white fibrous tissue whose top and bottom are formed by the opposed articular surfaces of the bones. The latter are covered by encrusting cartilage and the whole is lined by a synovial membrane furnishing the fluid which lubricates the joint. All synovial membranes are protected by more or less complete capsules ; but the fibers in some joints are so much thicker in some parts than in others, that they are spoken of as if they were separate liga- ments, though always blended with the capsule. Movements. The head rocks backward and forward on the condyles which move in the receiving cavities of the atlas. There is some lateral movement also. Move- ment forward is flexion, backward, extension. At the atloaxoid joints, the atlas alone moves. It revolves to either side around the odontoid process, the articular 56 ANATOMY FOR NURSES process of the side to which movement is made gliding backward, and the other forward. Bending the body forward is flexion; backward exten- sion; to either side, right or left lateral flexion. In forward movement the front of the intervertebral disks is compressed and the supraspinous and interspinous ligaments stretched, the inferior articular process of each vertebra gliding upward. The reverse takes place in extension. The corresponding mechanism would produce lateral movement. The performance of each of these movements in succession would be circumduction. COSTOVERTEBRAL ARTICULATIONS The ribs are held to the vertebral column by a three pronged bundle running to each of the vertebrae with which the rib articulates, and to the intervertebral disk, from the front of the head; by a small band between the ridge on the head of the rib and the intervertebral disks ; by capsular ligaments surrounding the articular facets; and by strong fibers running from the back of the neck of the ribs to the front of the transverse pro- cesses and capsular ligaments surrounding these articu- lar facets. Movements. The lower anterior end of the ribs moves upward, revolving on an axis formed by the transverse processes. This thrusts the sternum forward and in- creases the diameters of the chest. ARTICULATIONS OF THE CLAVICLE The clavicle articulates with the sternum by a sad- dle-shaped joint. An inter articular plate of cartilage is ARTHROLOGY 57 interposed between the bones, attached at the top of the clavicle and at the bottom of the receiving cavity. A capsule surrounds the joint. A strong bundle extends from the cartilage of the first rib to the rhomboid im- pression of the clavicle. The clavicle articulates with the acromion process of the scapula by an arthrodial joint. Sometimes there is a cartilage between the bones and a capsule always binds them together. This is a very poor security, so the joint is reinforced by powerful fibers which run upward from the coracoid process where the clavicle crosses it to the under surface of that bone. These fibers are de- scribed as the conoid and trapezoid ligaments because the shape is different. Viewed from behind they form a cone, from in front, a trapezium. Movements. The clavicle can move freely in any di- rection at either end, though the range of movement is limited. At the inner end the least degree of move- ment is upward, as in lowering the shoulder. In all movements the shoulder is carried in a direction op- posite that in which the head of the clavicle moves. At the outer end the scapula is the more movable bone. THE ENARTHRODIAL JOINTS These are but two, the shoulder and hip. In each the receiving cavity is deepened by a fibrocartilage sur- rounding the margin of the cavity and called the glenoid ligament, but the glenoid ligament of the hip is the stronger and deeper and has to bridge the gap at the lower inner acetabular rim. Each has, as almost its only ligament, a strong capsule thickened at certain 58 ANATOMY FOR NURSES points ; but the capsule of the shoulder is long and per- mits a wide separation of the bones, while that at the hip holds the femur in close contact with its cavity. The capsule at the shoulder is attached around the anatomical neck of the humerus; that of the hip is fastened just internal to the trochanters, so that all the neck of the femur is in the cavity of the joint. The strengthening bands of the shoulder are unimportant; one of those at the hip, the Y ligament, having its tail fastened to the inferior anterior spine of the ilium and its spreading limbs to the anterior intertrochanteric line, is, surgically, of the highest importance. A round bundle, ligamentum teres, running from the head of the femur to the bottom of the acetabulum is peculiar to the hip. Each joint has an extensive synovial membrane which, as elsewhere, lines the interior of the capsule as well as covers the bones. Each is greatly strengthened and protected by surrounding muscles; but the shoulder is more dependent upon this "ligamentous action of muscles" than the hip. Each possesses great number and range of movements, though the range is much greater at the shoulder ; and in each the movements can be described in nearly identical words. Movements. Flexion in both cases is movement for- ward. At the shoulder the head of the humerus spins around an axis drawn from the great tuberosity through the center of the head ; at the hip the axis is drawn from the great trochanter. Extension is the reverse of flexion. Abduction is movement of the arm or thigh away from the midline of the body, the head gliding down in either case, pressing on the inferior fibers of the capsule liga- ment, rupturing it and being dislocated if exaggerated. ARTHROLOGY 59 Adduction is the reverse. Circumduction is the succes- sive performance of these four angular movements. Axial rotation, performed at these two joints alone, is move- ment, inward or outward, causing the whole bone to spin around an axis drawn from the center of the head to the inner tuberosity, or condyle. THE GINGLYMOID OR HINGE JOINT The chief hinge joints are the elbow, knee, ankle, and interphalangeal. They are so dissimilar that separate descriptions of each must be given. The radius and ulna both enter, with the humerus, into the elbow joint. These bones of the forearm are held together above by an encircling ligament, the orbic- ular, attached at each end of the lesser sigmoid cavity and binding the radius firmly to the ulna. Below an- terior and posterior fibers extend between the two bones and a triangular cartilage, attached by its base be- tween the two articular cavities and by its apex to a pit between the two processes of the ulna, at nce binds these bones together and cuts the ulna out of the wrist joint. The shafts are bound together by a thin but strong membrane attached to their interosseous ridges. This firm binding of the two bones together keeps the radius from independent action at the elbow. In revolving around the ulna it spins on the humerus, but it must follow the ulna in movement of the elbow joint. The chief ligaments concerned in the elbow joint are the internal and external lateral. The first is the strong- est. It is attached by its apex to the inner condyle and by its base to the olecranon and coronoid processes 60 ANATOMY FOR NURSES where they form the margins of the great sigmoid cav- ity. The external is fastened above to the outer eondyle and below to the orbicular ligament, not touching the radius as it would interfere with it in revolution. The anterior and posterior are hardly more than fibers of the capsular ligament, the work of these ligaments be- ing performed by muscles. The synovial membrane lines the superior radioulnar joint as well as the elboAv. Movements. Flexion, movement forward, and exten- sion are the only movements. The joint is not a straight line, owing to the greater length of the inner ridge of the trochlea, and the movements are not straight. In extension the foramen is carried away from the midline making an angle open outward. The knee joint is the largest and most complex in the body. The condyles of the femur rest on the glenoid cavities of the tibia and are bound to it by ligaments both inside and outside the joint, and the patella plays on the trochlea connecting the condyles. The cavities of the tibia are deepened by glenoid ligaments, but these rest on the tibia without being directly attached to it and, consequently, participate in the movements and accidents of the joint. The interior ligaments, called crucial, are two in num- ber and are attached, the anterior in front of the spine and to the outer side of the condyloid notch, the posterior behind the spine and to the inner side of the same notch. The external lateral is fastened to the outer tuberosity above and below, in two bundles, to the styloid process and head of the fibula. The internal lateral, broader and somewhat triangular, seizes the inner tuberosity of the femur above and below ARTHROLOGY 61 spreads out over the inner tuberosity and upper part of the shaft of the tibia. The patella is enveloped, except on its posterior face, in the tendon of the great extensor of the leg. The lower part of this tendon runs from the lower end of the patella to the lower part of the anterior tubercle of the tibia, supplying the place of an anterior ligament. It is called ligamentum patellae. The nnstwjflr Ugmme/nt is, in the main, the expanded tendon of the semimembranous muscles, inserted into the tibia below and passing upward to seize the femur be- tween and above the condyles. The synovial membrane is very extensive, lining the interior of all the ligaments except the crucial which it covers and excludes from the synovial cavity, running under the glenoid ligaments and communicating with bursae around the joint. Bursae are svnovial sacs, like water bags, placed under many tendons around joints. They are very numerous around the shoulder, knee and hip. They contain synovia. Some do not communicate with joints and contain mucus. Movements. Movement backward is flexion. The leg is carried upward against the thigh, the glenoid cavities moving backward on the condyles and the patella glid- ing downward on the trochlea. The reverse is exten- sion. The greater length of the internal condyles causes some rotation in these movements, inward in flexion, outward in extension. The ankle is a peculiar form of hinge. The oblong hole a carpenter makes to receive a suitable projection of timber is called a mortise. The projection is called a tenon. In this joint the tibia and fibula furnish the 62 ANATOMY FOR NURSES mortise, the astragalus, the tenon; both are wider in front than behind. The internal lateral or deltoid ligament is a thick strong bundle attached above to the inner malleolus and below, by its base, to the astragalus, os cacis and scaph- oid. It binds these bones of the foot together in ad- dition to being the strongest ligament of the ankle. The external lateral, arising from the outer malleolus, splits into three fasciculi, or bundles, which are attached in front to the aotragalus, in the middle to the oo- oaleis and behind to the aslxagalus.*j d4/r4///A-~ The anterior and posterior are nearly negligible as ligaments, but the place of a posterior is supplied by the great extensor of the foot, called tendo Achilles. A syno- via! membrane lines all the structures. Movement. Flexion brings the back of the foot up toward the leg and forces the tenon backward in the mortise. Extension is the reverse, pointing the toes downward and, by bringing the narrowest part of the k ' ton<5a into the broadest part of the mortise, allows slight lateral play and places the joint at great disadvantage as to sprains. THE CONDYLOID ARTICULATIONS The joints of this variety are the wrist, temporo- maxillary, occipito-atloid and metacarpo-phalangeal. The condyle of the wrist is furnished by these bones of the first row of the carpus, scaphoid, semilunar and cuneiform; the cavity by the lower end of the radius and the cartilage which cuts the ulna out of the joint. Ligaments called anterior, posterior, internal and external lateral unite with each other to form a capsule ARTHROLOGY 63 and are attached to the radius chiefly above and the first row of the carpus below. Movements. Condyloid joints have all movements ex- cept axial rotation. In every movement the condyle glides in a direction opposite that taken by the part moved ; i. e., if the hand moves inward the condyle moves outward, etc. The temporo-maxillary joint is a condyle on each side and a glenoid cavity formed on the squamous part of the temporal bone. An interarticular cartilage lies between the bones and moves with the coiidyles. A capsular ligament strengthened particularly on the outer side, where it is called the external lateral ligament, binds the bones together. Some bundles of cervical fascia are also classed as ligaments. Movements. The jaw moves upward in crushing food, downward in opening the mouth, and alternately to each side in grinding food. In the latter movement the con- dyles glide alternately backward and forward; i. e., if the jaw is trust to the left, that condyle goes backward and the right forward. In the metacarpo- and metatarso-phalangeal joints the long diameter is from before backward while the receiving cavity is almost circular. The chief liga- mentous action is exerted by the extensor-tendons on the back and a fibrocartilaginous mass connected with the flexor tendons on the front. This is true also of the in- terphalangeal joints of both hand -and foot. These are trochlear or hinge articulations. Movements. At the metacarpo- and metatarso-phalan- geal joints some lateral movement is permitted, particu- larly at the joints on the free (i. e. outer and inner) sides 64 ANATOMY FOR NURSES of the hand and foot. The interphalangeal joints can perform only flexion and extension. Flexion is forward in the hand and downward in the foot. The intercarpal and carpo-metacarpal joints are ar- throdia bound together by dorsal and palmar ligaments and, on the free borders, by lateral ligaments as well. This is not true of the metacarpal bone of the thumb and the trapezium, which is a saddle-shaped joint with a cap- sular ligament. The intertarsal joints are much larger than the in- tercarpal. The astragalus and os calcis are mainly bound together by fibers filling the sinus tarsi and form the first row of the tarsus. The second row is held together by dorsal and plantar ligaments and is held to the first by very strong plantar ligaments which pass from the os calcis to the cuboid and the scaphoid. These ligaments are very important in maintaining the arch of the foot. The tarso-metatarsal joints are so similar to the cor- responding joints of the hand that no separate descrip- tion is needed. PELVIC LIGAMENTS The pubic bones are bound together by a plate of fibrocartilage between their inner ends and by liga- ments above, below, behind, and in front. The sacrum is united to the ilia by anterior and posterior fibers, of which the latter are much the more powerful. A very large bundle is attached to the side of the sacrum and coccyx by one end and splits to seize the spine and tu- berosity of the ischium at the other, closing the deep ARTHROLOGY 65 Fig. 7. Pelvic ligaments and capsule of hip. 66 ANATOMY FOR NURSES gap between sacrum and ischium and converting the sciatic notches into the sciatic foramina, greater and lesser. A membrane called the triangular ligament fills the space between the ischio-pubic rami while a similar membrane, the thyroid, fills all but the top of that foramen. CHAPTER IV MYOLOGY Muscles are striated or nonstriated. In the study of myology only the striated are considered. Muscles lie beneath the skin and superficial fascia in all parts of the body and beneath a special membrane called the deep or investing fascia in some parts. These fascias are studied with the muscles. The superficial fascia lies just beneath the skin, which it enables to move freely, and carries the greater part of the body fat and the superficial blood vessels and nerves. As it has no bony attachments, it permits collections of fluid or air to spread widely through or beneath its meshes. The deep fascias, most pronounced in the neck and upper and lower extremities, seek attachment to bone at every opportunity, and hence limit the spread of any accumu- lation beneath them. They also send down septa be- tween muscles and groups of muscles, by which the area for muscular attachment is greatly increased without adding to the weight of the body, as a corresponding increase of bone would. Muscles are sometimes spread out in broad sheets, but are more frequently gathered into large bundles of varying shape and direction. As their function is to produce movement of some sort, they run over mov- able joints and are fastened on either side of one or more such joints. These attachments are spoken of as the origin and insertion, the least movable point usually being the origin. These attachments take place through 67 68 ANATOMY FOR NURSES long or short masses of white fibrous tissue called ten- dons. Sometimes the tendinous fibers are imperceptible to the unaided eye, when the attachment is said to be fleshy; in other cases some tendinous fibers can be seen and this is called a nnisculo-tcmlinous attachment. In still other cases the tendon is spread out in a thin sheet when it is called an aponeurosis. . Muscular nomenclature is very difficult, because there are so many muscles and the names have been derived from such a variety of sources. Those producing an- gular movements are flexors, extensors, abductors and adductors. Others are named from the direction of their fibers, shape, from points of attachment, etc. As the physiologist seldom pays attention to the action of individual muscles, the anatomist spends an unusual amount of time on this subject. Muscles act very much as a stretched piece of rubber does; that is, by getting shorter and thicker. If a movable joint is between the attachments, such shortening will bring the two bones nearer together; or, if a cavity is beneath the muscle, and the bones do not move, the size of the cavity will be diminished. If, thereiore, the points of attachment are given and the joints are known, the chief function of a muscle may be inferred. It makes little difference at what point the study of the muscular system is begun. In actual practice it is convenient to begin with the abdominal wall because one can sooner see and study the abdominal viscera. THE ABDOMINAL MUSCLES This group consists of three pairs of broad and two of smaller muscles. The broad, and one pair of slender, MYOLOGY 69 Fig. 8. Muscles. Front of neck., trunk, and upper extremity. 70 ANATOMY FOR NURSES muscles are named from the direction of their fibers two oblique, one transverse, and one straight. The re- maining pair receive their name from their shape pyramidal. The oblique muscles are external and internal and be- neath them is the transverse. The fibers of the external oblique run downward and inward; of the internal oblique, upward and inward, and those of the transver- salis run around the body, from behind forward. It is evident that this arrangement makes a net w r ork of fibers around the abdomen so that, when the muscles shorten, or contract, pressure is made on the contents of the abdomen in various directions. The external oblique arises from the eight lower ribs and is inserted into the crest of the ilium and spine of the os pubis. The part of the tendon stretching from the anterior superior spine of the ilium to the pubis is called Poupart's ligament and is free between its points of attachment. The remaining fibers are in- serted into the linea alba. This is a thickened mass of fibers stretching from the ensiform cartilage to the sym- physis pubis made up of fibers from all the broad mus- cles of the abdomen. The internal oblique is attached below to the outer part of Poupart's ligament and the crest of the ilium. Above it seizes the four lower ribs and the whole length of the linea alba and the crest of the pubis. The transversalis rises from the outer half of Pou- part's ligament, the crest of the ilium, the spines of the lumbar vertebrae and from the inner faces of the six lower ribs, and is inserted into the linea alba and the crest of the pubis, MYOLOGY 71 The recti are flat muscles arising from the front of the symphysis pubis and its crest and inserted into the fifth, sixth, and seventh ribs beside the sternum. These muscles lie on either side of the linea alba and are en- closed in a sheath furnished by the aponeuroses of the broad muscles. The pyramidalis lies in the sheath of the rectus, is sometimes wanting and rather unimportant. Opposite the spine of the pubis there is a hole in the aponeurosis of the external oblique which transmits the round ligament in the feniale and the sperniatic_cprd in the male. It is called the superficial abdominal ring. The abdominal wall is thus seen to consist of skin, superficial fascia which contains much fat, the external oblique, internal oblique, transversalis, a delicate fascia like the superficial, and a sort of internal skin called the peritoneum. Action. By contracting, these muscles decrease the size of the abdominal cavity, compressing its contents and expelling parts of them through the openings pro- vided for the purpose urethra, rectum and vagina. They can also bend the body on the pelvis or the pelvis on the body. The diaphragm, the great respiratory muscle, is a thin dome, when in position, though shaped like a palm- leaf fan when cut out and spread flat, separating the thoracic from the abdominal cavity. The floor of the thorax is, therefore, convex and the roof of the abdo- men concave. The muscle springs from the inner faces of the six lower ribs, where it interlocks with the transversalis, and by two long tendons, which leave a space between 72 ANATOMY FOR NURSES them for the abdominal aorta, from the bodies of the lumbar vertebrae. Between the last rib and the side of the spine two tendinous arches, called ligamenta arcu- ata interna and externa, give origin to fibers which fill in what would otherwise be a gap in the muscle. The insertion is into a central tendon, shaped some- thing like a clover leaf, and called trefoil. It follows that the fibers proceed in different directions. Those from the ribs are directed upward and inward, those from the vertebras, upward and forward, all convex upward and outward or backward. The diaphragm allows structures to pass from the thorax to the abdomen either through or behind it. The aorta passes with the thoracic duct and other structures through the aortic opening which is behind. The opening for the esophagus is above and in front of the aortic and that for the inferior vena cava is in the central tendon and still higher up. Action. If the. ribs are fixed when the diaphragm contracts, the whole muscle is pulled downward. At the same time the curved fibers become straight, leaving a greater interval between them and the ribs. All this increases the size of the thorax. The muscle is the great agent of inspiration. THORACIC MUSCLES Two muscles, pectoralis major and minor, occupy the front of the chest ; the serratus magnus, the sides ; and the intercostals, the spaces between the ribs. Except the latter, these are as much muscle of the upper ex- tremity as of the trunk. MYOLOGY 73 The pectoralis major occupies the front of the ster- num, a part of the clavicle and five of the ribs. It is inserted into the outer bicipital ridge of the humerus. The pectoralis minor springs from the third, fourth and fifth ribs and is inserted into the coracoid process of the scapula. CXv\J\AA-i^ /v The serratus magnus- springs from the eight upper ribs and, running between the scapula and the thorax, is inserted into the posterior border of the scapula. Action. They all tend to draw the upper extremity toward the midline, i. e., they are adductors, or act from their insertion. They tend to draw the ribs apart and expand the chest. MUSCLES OF THE CERVICAL REGION Except the platysma, these muscles are enclosed in a deep or investing fascia, the cervical, which fastened to the spines of the vertebrae behind, runs around the entire neck like a high stock, and is fastened behind where it started. Above, it is fastened to the lower jaw, and below, to the clavicle and to structures in the thorax. It not only binds everything in the neck in an envelope, but sends off partitions which form sheaths for muscles and blood vessels. The platysma myoides is a thin muscle spreading over the sides of the neck beneath the superficial and above the deep fascia. Deeper than this muscle, in a sheath of the deep fascia, lies one of the most important muscles of the body, sterno-cleido-mastoid whose name indicates its attachment. It arises from the clavicle and sternum and, running upward 'and backward across the 74 ANATOMY FOR NURSES side of the neck, is inserted into the mastoid process of the temporal and the occipital bones. It can be felt throughout its course, Action. The two bow the head, or either, acting alons, can pull the head toward the shoulder and turn the face to the opposite side. The hyoid bone separates the next layer into two groups distinguished as suprakyoid, or elevators, and infrahyoid, or depressors of the hyoid bone. Two of the depressors, sterno-hyoid and sterno-thy- roid, spring from the back of the sternum and are in- serted into the body of the hyoid and wing of the thy- roid cartilage respectively. A short muscle called thyro-hyoid continues the latter to the hyoid. The omo-hyoid runs nearly inward from the upper border of the scapula, forms a central tendon which plays through a loop of fascia which binds it to the first rib, then turns nearly upward to reach the hyoid. Two of the elevators of the hyoid, genio- and mylo- hyoid, are attached to the lower jaw and the hyoid bone ; one the digastric, is double bellied and is pulled down to the hyoid by a loop of fascia, being fastened at one end to the temporal bone and the other to the lower jaw. The stylo-hyoid may be omitted. The niylo- and genio-hyoids aid in forming the floor of the mouth. Action. These muscles can either elevate the hyoid bone or depress the lower jaw. A deeper group, of which the scaleni and recti are the most prominent, are flexors, anteriorly or laterally, of the vertebral column, or, like the scaleni, elevators of the upper ribs and inspiratory agents. MYOLOGY 75 MUSCLES OF THE HEAD AND FACE The muscles of expression are a group of small mus- cles usually attached to bone at one end and the skin of the face at the other. Their contraction causes a change of expression. Among the important muscles of this region are the muscles of mastication used in chewing the food. The temporal muscle occupies the fossa of the same name and is, like it, fan-shaped. Below it grasps the coronoid process of the lower jaw. The masseter is attached to the zygomatic arch above and the ramus of the jaw below. The pterygoids, internal and external, are attached to the base of the skull and below, to the lower jaw, the inner seizing the ramus, and the outer, the neck of the condyle. There is a thin flat muscle in the cheek, the buccina- tor which is classed with the masticators because it holds the food between the teeth. Its paralysis causes the food to bulge out the cheek. Action. All but the external pterygoid are elevators of the jaw and hence crushers of food. The outer pterygoid causes lateral motion and protrusion for- ward. It is a grinder of food. ORBITAL GROUP The eyeball is moved in its socket by four muscles called recti and two called oblique. The recti are superior, inferior, internal and external. They are ar- ranged around the eyeball as their names indicate and 76 ANATOMY FOR NURSES MYOLOGY 77 each pulls so as to turn the eye upward, downward, inward or outward. All but one of the muscles of the eyeball rise from the corresponding margin of the optic foramen and are insered into the outer (sclerotic) coat of the eye. The superior oblique rises from the margin of the optic foramen, passes through a pulley at the upper in- ner part of the eye and its tendon then runs downward and outward to the sclerotic. The inferior oblique rises from the upper jaw, within the orbit, and passes outward, beneath the eyeball to reach the same coat on its outer side. Hence it revolves the eye outward, while the superior revolves it inward. The elevator of the upper lid (levator palpebrae superioris) also lies in the orbit, rising from the margin of the optic foramen and being inserted into the upper tarsal cartilage. MUSCLES OF THE BACK The superficial fascia of the back, thick and rather coarse, is continuous with that of the axilla, abdomen, neck, and buttock. Beneath it is a broad expanse of aponeurotic fibers, forming the vertebral aponeurosis and giving attachment to many muscles. The muscles of this region are arranged in layers from behind for- ward. The first layer is made up of two muscles, the trapezius above and latissimus dor si below. The two ex- tend from the back of the occiput to the sacrum. The trapezius (the two together are diamond-shaped) arises from the occiput and cervical and dorsal spines and is inserted into the spine of the scapula and the outer third of the clavicle. 78 ANATOMY FOB NURSES Fig. 10. Muscles. Back of trunk, upper extremity, and hips. MYOLOGY 79 The latissimus dorsi stpts, underneath the trapezius, from about the sixth dorsal spine, and rises from the dorsal and lumbar spines, the back of the sacrum, the posterior third of the ilium and three or four of the lower ribs. Its tendon passes over the lower angle of the scapula and is inserted into the inner bicipital ridge of the humerus. Action. The trapezius draws the scapulas together and elevates them. The latissimus draws the humerus down- ward and backward. The muscles of the next layer are the rhomboid, which is attached to the lower cervical and upper do? a 1 . spines and the peste^r border of the scapula ; and the levator anguli scapulae which rises from the upper cer- vical transverse processes and is inserted into the up- per angle of the scapula. It draws the scapula upward and inward while the rhomboid draws it inward. A large mass of muscular and tendinous fibers fills the sacral groove and the space on either side of the vertebrae column. It is called erector spinae and is con- tinued by a succession of alternate origins and inser- tions up to the skull. It maintains the body in the erect posture and can restore it to that position after flexion. MUSCLES OF THE UPPER EXTREMITY Scapular group There are five muscles in this group largely con- cerned in rotation of the humerus. Three are named from the scapular fossae from which they arise while the other two spring from the axillary border and are called teres (round) muscles from their shape. 80 ANATOMY FOR NURSES The subscapularis arises from the fossa of that name on the front of the scapula and is inserted into the small tuberosity of the humerus. It is an inward ro- tator. The supraspinatus arises from the supraspinous fossa ; the infraspinatus, from the infraspinons fossa; the teres minor, from the axillary border of the scapula; and are inserted in the order given, into three impres- sions on the great tuberosity. The last two are out- ward rotators ; the first an abductor of the humerus. The teres major rises from the lower part of the axil- lary border of the scapula and is inserted with the latis- simus dorsi into the inner bicipital ridge. It acts with that muscle and is an inward rotator. The rounded outline of the shoulder is largely due to a bulky muscle called deltoid. It covers the joint in every aspect except below and internally. It is at- tached above to the spine and acromion of the scapula and the outer third of the clavicle. Below it seizes the outer face of the humerus about half way down. The humeral group is made up of three muscles in front and one behind. They are enclosed in a strong fibrous envelope which encircles the arm and blends with a strong fascia covering the axillary space and pectoral muscles. Below this fascia seizes the condyles of the humerus and is continued over the muscles of the forearm, forming a special thickening on the front and back of the wrist called anterior and posterior annular ligaments. It is then continued into the hand ,-is ihc palmar fascia. The triceps (three heads) is on the back of the hu- merus. Its long or middle head rises from the scapula MYOLOGY 81 and the other two from the back of the humerus. All are inserted into the olecranoii process. The biceps (two heads) rises from the coracoid proc- ess and margin of the glenoid cavity of the scapula and is inserted into the bicipital tuberosity of the radius. It and the triceps pass over two joints. An offshoot from the inner head is called the coraco-brachialis and is in- serted into the inner face of the humerus. The brachialis a&tiefr springs from the lower half of the front of the humerus and is inserted into the 'TV Action. The triceps extends the forearm; the biceps and brachialis antious flex it, and the biceps is a su- pinator. The coraco-brachialis is an adductor and flexor of the arm. - The muscles of the forearm are arranged in anterior . and posterior groups, and each of these in two layerar, All muscles on the front are either flexors or pronat&rs; and all on the back are either extensors or supinaiors^J ^ On the front a great mass composed of five muscles springs from the inner coiidyle of the humerus. As this mass passes downward, it gives off first a round muscle, the pronator radii teres which is inserted into the mid- dle of the radius; a slender tendon, the flexor carpi radialis, inserted into the metacarpal bone of the index finger; a still smaller tendon, the palmaris longus in- serted into the palmar fascia; a group of four tendons seizing the middle phalanx of each of the four fingers; and a more muscular tendon which is fastened to the metacarpal bone of the little finger. These are the flexor sublimis digit orum and the flexor carpi ulnaris. Beneath these are three muscles, the flexor longus 82 ANATOMY FOR NURSES pollicis rising from the radius and inserted into the last phalanx of the thumb; the flexor profundus digitorum, arising from the ulna and inserted into the last phalan- ges of the fingers ; and the pronator quadratus spring- ing from the lower fourth of the ulna and seizing the same amount of the radius. Action. Pronation is revolving the radius, carrying the hand so as to turn the palm backward, and supina- tion is the reverse. As movement forward is flexion in this extremity, the flexors have their function indicated by their names. Thus the flexor carpi radialis flexes the wrist but draws it to the radial side; the uliiaris pulls to the ulnar side, while the digital flexors are dis- tinguished as superficial (sublimis) and deep (profun- dus) and act on the phalanges into which they are in- serted. After flexing the fingers, they can act on the joints above. On the back of the forearm the superficial muscles rise from the external condyle and branch into a short radial extensor (extensor carpi radialis longior), a com- mon extensor of the fingers (eommtinls digitorum), an an extensor of the little finger (Extensor minimi di-giti) and an ulnar extensor (Extensor carpi ulnaris). Ex- tensors of the fingers are attached to the whole length of the back of the phalanges, furnishing posterior liga- ments of the joints as they pass over them. The short radial extensor is attached to the metacarpal bone of the middle finger, and the ulnar, to that of the little finger. The deep group comprises five muscles. The first of these, the supinator -bre^fe runs from the ulna around the upper extremity of the radius, which it seizes. The MYOLOGY 83 next three are attached to one or both bones of the fore- arm above and, in consecutive order from above down- ward, to the metacarpal bone, first and second phalan- ges of the thumb. The last is attached above to the ulna and below to the index finger like all extensor tendons. Two muscles, brachio-radialis and long radial exten- sor (Extensor carpi radialis longlor), are attached above to the ridge above the outer condyle and below the first to the styloid process of the radius and the second to the metacarpal bone of the index finger. The palm of the hand is covered by a very dense fascia which is attached to the skin and prevents its freedom of movement. This fascia is much thicker cen- trally than on either side, where it covers two groups of muscles, the thenar at the base of the thumb and the hypothenar at that of the little finger. The thenar muscles either flex the first phalanx of the thumb, or draw the thumb to or away from the middle of the hand, or approach the thumb to the little finger. Hence the muscles rise from near the middle of the hand. The hypothenar group perform similar functions for the little finger, but their origin is close to the inner side of the hand. Certain small muscles called interossei and lumbricales occupy the middle of the palm."" MUSCLES OF THE LOWER EXTREMITY The fascia of the lower extremity envelopes that part in a way similar to that found in the upper extremity. It covers the region of the hip, seizing not only the crest 84 ANATOMY FOR NURSES of the ilium and the os pubis but Poupart's ligament as well. In the thigh it is called facia lata. Descending to the knee it forms a strong roof for the popliteal space, back of the knee joint, seizes the .tuberosities of the tibia and head of the fibula and descends the leg, enveloping the muscles and sending septa between them, as it does in the upper extremity and thigh, forms an anterior and two lateral annular ligaments, and ends by becoming more or less continuous with the plantar fascia. Here the muscles of the hip correspond to those of the shoulder; those of the thigh, to the arm; of the leg, to the forearm; and of the foot, to the hand. GLUTEAL GROUP The hip muscles form a group of nine, arranged in three layers, all having their origin from the innomi- nate and all inserted into some part of the upper end of the femur. These are called gluteal and are distin- guished as greater, middle, and least, (maximus, medius and minimus). Besides being concerned in rotation, like the shoulder or scapular group, some of these muscles have the important function of sustaining the body in the erect posture by steadying the pelvis on the femur and preventing the falling over which would occur were they paralyzed. The three gluteal muscles are engaged in this way. They are found occupying all the outer sur- face of the ilium and its crest above and below and are inserted either into or near the great trochanter. Of the remaining muscles of this group two, obturators internus and externus, spring from the obturator membrane; a third, the pyriformis with the obturator internus, rises MYOLOGY 85 within the pelvis and all are inserted into or near the pit on the inner face of the great trochanter. All, except the gluteus minimus, which rotates inward, are outward rotators of the femur. The muscles of the thigh are arranged in anterior, posterior and internal groups. On the front of the thigh the muscles are either flexors of the thigh on the pelvis or extensors of the leg on the thigh. The posterior muscles are all flexors of the leg and the internal adductors of the thigh. There are really but two muscles on the front, though they are usually described as five and some- times seven. The-Jbiceps.- flexo^-^emoris has a long head called psoas magmis, which springs from the lumbar verte- bra?, and a short, the iliacus inter nus, springing from the iliac fossa. It passesTunder Poupart's ligament and is inserted into the lesser trochanter. The triceps extensor cmris rises from just above the acetabulum by a long middle head called rectus; a short external called vast us smcrnus^ springs from .the. outer part of the femur and a shorter, vastus infonvus, from the inner and front part of that bone. They unite to form a strong tendon which encloses the pa- tella and is inserted into the anterior tubercle of the tibia, forming the anterior ligament of the knee joint. The internal and external intermuscular septa give at- tachment to the two shorter heads. The adductor, or internal group, has four heads called pectineus and adductors longus, brevis, and magnus. Their points of origin can be separated but the insertion can not. They spring from the pectineal triangle and 86 ANATOMY FOR NURSES outer face of the os pubis, and from the tuberosity and ramus of the ischium. They all run outward and downward and are inserted into linea aspera. Inclosed between layers of the fascia lata are three thin muscles, on the outer, inner, and anterior aspects of the thigh, named tensor vaginae femoris, sartorius and gracilis. The first rises from just back of, and the second from the anterior superior spine of, the ilium, and the last from the margin of the pubic symphysis. The tensor is inserted into the fascia lata about half- way down. The sartorius and gracilis, along with the semitendinosus, blend together to form what is called the " goose foot" insertion into the inner face of the tibia just below the tuberosity. The gracilis runs straight downward, the sartorius obliquely downward and inward at first and then straight downward. Its course is important because of its relation to the fem- oral artery. The tensor's action is indicated by its name. The gracilis is an adductor of the leg and thigh; the sartorius draws one leg across the other. In the posterior region there are three muscles, biceps fUxo^Li^u^is semitendinosus and semimembra- nosus. All of them spring from the tuberosity of the ischium. The semitendinosus and long head of the biceps rise in common and pass down the thigh to below its mid- dle, where the short head of the biceps, which rises from the outer lip of the linea aspera, joins the long and the two muscles diverge to form the upper boun- daries of the popliteal space. The biceps is inserted into the head of the fibula while the semitendinosus goes to the "goose foot" insertion. MYOLOGY 87 The semimembranosus lies a little in front of the~ other two but also rises from the tuberosity of the ischium. It passes to the inner side of the popliteal space and is mainly inserted into the groove on the inner tuberosity of the tibia, but a large part goes into the posterior ligament of the knee joint. Action. They all flex the leg on the thigh. In stand- ing and walking they act from below, pulling on the tu- berosity of the ischium, preventing the tendency to fall forward. They aid in restoring the body to the erect posture after bending forward at the hips. TW T O layers of muscles, superficial and deep, are found on the back of the leg and one each on the front and outer side. The superficial layer at the back is the triceps surae whose heads are the gastrocnemius, plantaris and soleus. The gastrocnemius rises from the two condyles of the femur, its outer head springing with the plantaris. The two heads form the lower boundaries of the popli- teal space. The soleus rises from the tibia and fibula for several inches. The three form the strongest tendon in the body, tendo Achilles, which is inserted into the lower part of the posterior tuberosity of the os calcis. Action. By pulling the calcis upward, it turns the toes downward. This raises the body on tiptoes; i. e., it is an extensor of the foot. The deep group contains the popliteus, tibialis posti- cus, flexor longus digit orum and flexor long us hallucis. The popliteus rises from the outer tuberosity of the femur and is inserted into the popliteal triangle of the tibia. 88 ANATOMY FOR NURSES The tibialis pe&tiotts rises mainly from the iiiteros- seous membrane, but from tibia and fibula as well. Its tendon lies on the concave inner face of the calcis to reach the tuberosity of the scaphoid and inner cunei- form. The flexor longus hallucis rises from the fibula and is inserted into the last phalanx of the big toe. It is much larger than the flexor of the toes. The flexor longus digitomm springs from the tibia and is inserted into the last phalanx of the four outer toes, i. e., corresponds to the flexor profundus in the upper extremity. The names explain the action ex- cept of the tibialis, which is an extensor of the foot. The anterior muscles are the tibialis anticus, extensor longus dig it or um find extensor proprius hallucis. The tibialis c a*Sictts rises from the tuberosity and up- per half of the outer face of the tibia and is inserted into the inner cuneiform and metatarsal bone of the big toe. It flexes the foot and turns it inward; i. e., inverts it. The extensor longus digitomm rises from the head and nearly the whole of the fibula and is inserted into the backs of the phalanges of the four outer toes and into the metatarsal bone of the little toe. The extensor jM^eprius hallucis rises from the middle two-fourths of the fibula and is inserted into the last phalanx of tiie big toe. The &utifgroup comprise the peroneus longus and brevis. They occupy the whole of the outer aspect of the fibula and, becoming tendinous, the brevis is in- serted into the metatarsal bone of the little toe, the longus into that of the big toe, having passed across MYOLOGY 89 the sole of the foot through the peroneal groove on the cuboid. All of the last five muscles, except the proprius hallu- cis, spring from the investing fascia. The peronei extend and evert the foot ; i. e., turn it so it rests on the inner side. The plantar fascia is much stronger than the palmar, but, like that, the middle division is the strongest. It covers, and gives origin to, three muscles which abduct the great and little toes and flex the four outer toes. These muscles all spring from the under surface of the calcis, as well as the fascia. Above them in the sole lie other layers of muscles which are not im- portant. The only muscle on the dorsum of the foot is the extensor brevis digitorum. It rises from the upper and outer part of the os calcis and, dividing into four tendons, is inserted into the first phalanx of the big toe and the whole length of the backs of the next three like all extensor tendons. The flexor tendons of the phalanges in both upper and lower extremities are bound to the bones, before insertion, in canals formed partly of bone, but on three sides by very tough fibrous tissue called thecce. These canals are lined by synovial membranes like joints. The extensor tendons of the phalanges all furnish posterior ligaments for the joints over which they pass. CHAPTER V SPLANCHNOLOGT The alimentary canal begins at the mouth and termi- nates at the anus. It consists of the mouth, pharynx, esophagus, stomach, small and large intestines. The pharynx succeeds the mouth and lies in the neck. The esophagus is in the lower neck and thorax while the digestive tract lies in the abdomen. The mouth presents thirty-two teeth set in the gums of the upper and lower jaws and described as four in- cisor, or cutting, teeth; two canine, or tearing; four premolar and six molar, or grinding teeth, in each jaw. These are the permanent teeth. The milk or deciduous teeth are twenty in number: four incisor, two canine, and four molar teeth in each jaw. Children begin to cut the teeth about the sixth month and the process continues up to about the thirtieth month. The order of eruption is the lower central incisors, upper in- cisors, lower lateral incisors and first molars, canines and second molars, each successive group appearing from two to six months after its predecessor. The mouth is lined by mucous membrane, which covers the tongue as well as the cheeks. On the cheeks are the openings of the ducts from the parotid salivary gland while those of the smaller submaxillary and sub- lingual open together beneath the tongue. The posterior opening of the mouth (oral cavity) called fauces, is a narrow opening leading into the ex- 90 SPLANCHNOLOGY 91 panded pharynx. The sides of the fauces are boundecT by the tonsils (amygdalae) so often the subject of dis- ease or the object of surgery. The upper part of the succeeding cavity is the nasopharynx and receives not only the posterior nares, but the openings of the eustachian tubes, by which air is carried into the middle ear. The oropkarynx is that part into which the mouth opens. Below the pharynx contracts to the esophagus immediately in front of which lies the larynx. The pharynx is, therefore, the space through which food is carried to the esophagus and in which the mouth, nose, ear and voice box com- municate. Its walls are partly formed by three mus- cles, called constrictors, so arranged that they overlap from below upward and each can grasp and force on- ward a morsel of food before it escapes the one above. The esophagus begins at the cricoid cartilage, and terminates, opposite the tenth or eleventh thoracic vertebra, in the stomach. Its muscular wall is made up of longitudinal and circular muscular fibers which run around the organ or throughout its length with no attachments beyond. In the neck and thorax the esoph- agus is closely related to important structures, es- pecially the great blood vessels. It lies directly be- hind the larynx and trachea, the speaking and breath- ing tubes. THE ABDOMEN AND ITS VISCERA The abdominal cavity contains the digestive and genito-urinary organs. It is lined by a membrane, the peritoneum, which is a completely closed sac in the male and nearly closed in the female. All the abdom- 92 ANATOMY FOR NURSES inal viscera are in some relation to the peritoneum, which forms a partial or complete coat for them the visceral peritoneum to distinguish it from the parietal which covers its walls. The viscera are thrust into the sac from behind and, as some are pushed much fur- ther than others, there are many cases in which this membrane performs the functions of binding the vis- cera to each other or the wall of the abdomen or sus- pending them from one or the other. The chief ligamentous folds are, one suspending the stomach from the lower surface of the liver, the lesser omentum; a large JL old running frcm the lower border of the stomach nearly to the brim of the pelvis and thence up to the transverse colon, which it invests and, indirectly, suspends from the stomach. This is called the great omentum, and splits into the layers of which the upper follows the abdominal wall and forms the posterior limit of the lesser cavity of the peri- toneum, a space behind the stomach, while the lower runs down over the small intestines, forming a liga- ment, the mesentery, which binds them obliquely from left to right over the three lower lumbar vertebrae. It then runs over the brim of the pelvis, covers the pelvic viscera, forming the ligaments of the bladder and, in the female, the broad ligament, a vertical fold which cuts the pelvis into an anterior and posterior compart- ment and envelopes the generative organs. That part of the alimentary canal found in the abdom- inal cavity is divided into the stomach, duodenum, je- junum and ileum and the large intestine which is sub- divided into cecum, ascending, transverse, and descending colon, the sigmoid flexure and the rectum. Besides these SPLANCHNOLOGY 93 hollow viscera the abdomen contains the liver, spleen, pancreas, kidneys, and suprarenal capsule, blood vessels, nerves and lymphatics. The abdominal alimentary canal is a long hollow tube, expanded at various points, nearly thirty feet in length and made up of an external peritoneal or serous coat, an internal mucous or digesting coat, a submucous coat of fibrous tissue, circular and longitudinal muscular coats. The muscular coats are uniformly distributed until the large intestine is reached, when the longitu- dinal coat is gathered into bundles situated on the front, back and inner sides. For convenience of de- scription, two imaginary lines may be drawn around the abdomen cutting it into an upper, middle and lower zone. One line is drawn between the anterior superior iliac spines and the other between the ninth costal car- tilages. Two other imaginary lines are now projected upward from the middle of Poupart 's ligament and the space is divided into nine regions. These are named, from above downward in the middle line epigastric, um- bilical and hypogastric. Those on either side are the hypochondriac right and left; lumbar, right and left; and the iliac, right and left. The stomach lies in the left hypochondriac (beneath the ribs) and the epigastric. Its large end is to the left and its walls look forward and backward. It is just under the liver and has the spleen close to its left end, which is a little below the heart from which it is sepa- rated by the diaphragm. The duodenum is the part of the small intestine suc- ceeding the stomach. It first runs upward to the under surface of the liver, then downward, about three inches, 94 ANATOMY FOR NURSES and then upward and to the left. Its course is deter- mined by the head of the pancreas around which it winds. It is nine inches long. The duct of the pancreas and that of the liver empty into the descending part. The jejunum and ileum, about twenty feet long, are the names given to the upper two-fifths and the lower three-fifths of the small intestine. They lie coiled up largely in the umbilical region, but some of the convo- lutions fall into the pelvis and surrounding regions. The mucous coat of the small intestine is thrown into transverse folds, valvulce conniventes, greatly increas- ing the absorptive area and retarding the floAV of semi- liquid food. The small intestine empties into the large in the right iliac fossa two and a half inches above the commence- ment of the latter. The part below the entrance is called the cecum The opening is the ileo-cecal and just below it the vermiform appendix opens into the cecum. As this appendix has no firm attachment, except to the cecum, its free end may point in any direction and is often attached, as the result of adhesions, to one of the pelvic or adjacent abdominal viscera. The ascending colon begins in the right iliac region, runs up through the right lumbar and terminates in the right hypochondriac, on the under surface of the liver, by becoming the transverse colon, which curves down- ward and to the left to just above the umbilicus, then turns upward and to the left to the spleen where it terminates in the descending colon, which runs from the left hypochondriac through the left lumbar to terminate in the left iliac in the sigmoid flexure of the colon, which forms a loop whose position varies with that of Transverse colon 1 Ascending colon 1 Caecum Appen lix | SPLANCHNOLOGY Descending cole Jejunum Fig. 11. Front view of organs. Semi-diagrammatic. 96 ANATOMY FOR NURSES the body but which runs over the brim of the pelvis to the middle of the sacrum when it changes its name to rectum which terminates at the anus. The curves in the large intestine made at the liver and spleen are called the hepatic and splenic flexures. The colon lies on the right, above and to the left of the convolutions of the small intestine. Food enters the stomach, where the pepsin and hy- drochloric acid are secreted, begins to be digested there, then passes into the small intestine, where it meets the pancreatic fluid and that of the intestine. Here diges- tion is continued and absorption goes on, decreasing in amount until finally, in the lower part of the large in- testine, there is nothing but the waste matter left. The liver, the largest glandular organ of the body, weighing about four pounds, lies in the right hypo- chondriac and epigastric regions. It is almost com- pletely covered by peritoneum and overhangs the stom- ach, ascending duodenum, hepatic flexure of the colon, and the right kidney. It has a deep antero-posterior fissure on its lower surface and, opposite this, a sus- pensory ligament on the upper surface, w T hich cut it into a large right and small left lobe. Its convex upper surface is in contact with the diaphragm, which sepa- rates it from the contents of the thoracic cavity, right lung and heart. On its lower. surface is the gall blad- der, w r hich holds its secretion, its ducts and the entrance of the artery and vein which are distributed to it. The branches of the portal vein and the hepatic artery ramify through the liver, conveying to it a large supply of blood, while the branches of the hepatic SPLANCHNOLOGY 97 duct run together to form a single duct which has a communicating branch, the cystic, by which the bile is conveyed to and from the gall bladder on the under sur- face of the liver. The union of the cystic with the two hepatic ducts forms the common bile duct which usually unites with the pancreatic duct before emptying into the lower part of the perpendicular duodenum. The Pancreas The pancreas is a compound racemose gland, like the salivary glands. It crosses the body of the first lumbar vertebra, from which it is separated by the abdominal aorta, inferior vena cava and the chief artery and vein of the intestine, and is covered only in front by the peri- toneum. The large head is embraced by the duodenum while the tail is in contact with the spleen. The upper border is on a level with that of the stomach, and just below this border the splenic vein lies on the back of the organ. This gland secretes the most important of the digestive juices. The Spleen The spleen, one of the ductless glands, lies in the left hypochondriac region, completely invested by peri- toneum which holds it to the stomach and diaphragm. It corresponds, by its convex outer surface, to the ninth, tenth, and eleventh ribs. The pancreas is bound to its concave inner face. It receives one of the largest of the visceral branches of the aorta and sends a vein, both named splenic, of corresponding size to the portal cir- culation. It is invested by a strong fibrous capsule and is subject to great variations in size. Normally it is about four inches long by two and a half inches wide. 98 ANATOMY FOR NURSES The Kidneys The kidneys are a pair of small organs, weighing about a quarter of a pound, lying in the lumbar region from the eleventh rib to the iliac crest on the quadratus lumborum muscle, whose outer borders extend a little beyond the twelfth rib. A depression in the back along the outer edge of the erector spinas muscle, indicates their position. The right kidney is a little lower than the left. The kidneys lie behind the peritoneum, which is usually separated from them by some fat. The right has the ascending colon and descending duodenum in front of it. The left has the descending colon. Each kidney has a deep notch the hilum on its inner border leading into a cavity, which lodges the duct and ves- sels of the organ. These are arranged with the vein in front, duct, or ureter, behind and artery between. The Urinary Bladder The bladder occupies the anterior part of the pelvic cavity, is a hollow sac made up of an internal mucous, two muscular, and a partial serous coat, having the ure- ters conveying the excretion of the kidneys into it and the urethra conveying it away. The bladder and its ap- pendages rest on the front of the rectum. In the female the internal generative organs lie between bladder and rectum. In both male and female, convolutions of the small intestines fall into the pelvic cavity and come in contact with the bladder and in both the peritoneum cov- ers the posterior half of the organ. The urethra in the female is very short, about two inches, and terminates at the upper part of the vaginal cleft. In the male this tube runs the length of the penis. In the male the pros- SPLANCHNOLOGY 99 tate gland surrounds the neck of the bladder and the seminal vesicles with the vasa deferentia internal to them, form a triangle between bladder and rectum. In the female these structures are wanting and their place is taken by the upper part of the vagina, the uterus, and its appendages. The Generative Organs in the Female These are the uterus, ovaries. Fallopian tubes and the vagina. The uterus is shaped like a flattened pear with its large end upward in the pelvic cavity and its small end surrounded by the vagina. It is covered by peritoneum, except where the vagina grasps it, and leans forward and upward. Its cavity communicates by a large open- ing, the os, through a constricted neck, with the vagina, and at each upper angle, through a Fallopian tube, Avith the peritoneal cavity. There is, therefore, a hole in the female peritoneum which does not exist in the male and a consequent danger of peritonitis. The uterus is held in position by folds of peritoneum be- hind, in front, and on each side, and by a round liga- ment which extends, from just below the Fallopian tube through the inguinal canal to the labium majus. The lateral ligament (broad ligament) is a vertical band which encloses the tubes, ovaries and round liga- ment and stretches to the lateral wall of the pelvis. It shuts off a cavity behind, which lies between the rectum and uterus, is known as the pouch of Douglas, and can hold a large amount of fluid. The ovaries lie one on each side of the uterus and are held to it by a round ligament developed in, the broad 100 ANATOMY FOR NURSES ligament. Its outer end is nearly in contact with, the iliac vein and, on the right side, it often touches the appendix. To its outer end, which is the higher, the fimbriated extremity of the Fallopian tube is attached. The function of the ovary is to produce eggs, that of the tube to convey the eggs to the uterus, and of the latter to hatch them. The hatching is called gestation and the act of birth parturition, which takes place through the vagina. The vagina is a tube with anterior and posterior walls the upper inch of which is in the pelvic cavity, covered on its posterior wall by peritoneum. Its an- terior wall is in contact with the bladder. Below it terminates in a slit-like aperture, cut vertically, which is surrounded by two thin folds, nymphae or labia minora, which are overlapped and hidden by larger folds, labia majora, which unite over the pelvic symphysis in the mons veneris. If the labia are separated a trian- gular space will be seen between the nymphae in front called the vestibule. At the back of the vestibule is the opening of the urethra and just in front of it the clitoris. These appearances are collectively called the vulva. The Generative Organs in the Male The chief male generative organs lie outside the pel- vic cavity and consist of penis and testicles. The penis consists of two parallel bodies, the corpora cavernosa, bound together by fibrous tissue, and a longer body opposite the interval between the cavernosa below called corpus spongiosum, which carries the urethra and turns up in front over the end of the cavernosa to form SPLANCHNOLOGY 101 ^ the glans penis which is pierced by the opening of the urethra, the meatus urinarius. Posteriorly the three bodies separate to form the root of the penis ; the lateral roots, the origin of the cavernosa, being attached to the rami ; and the central body, or bulb, being attached to the triangular ligament. The testicle, originally an abdominal organ which descends through the inguinal canal to the scrotum, is the secreting organ in the male analagous to the ovary in the female. The two testicles lie in a pouch of skin and unstriped muscular fibers, lined by a serous mem- brane, called the scrotum. The serous membrane covers the testicle and lines the scrotal sac. It is called tunica vaginalis. The testicle is suspended by a rounded cord made up of the cremaster muscle, blood vessels, nerves and lymphatic and the duct of the testicle, the vas deferens. The vas enters at the hole in the external oblique, passes along the inguinal canal, crosses the external iliac artery and vein to the base of the bladder where it joins a coiled tube, the seminal vesicle, a small reservoir for the seminal fluid, forming the ejaculatory duct which passes the seminal fluid into the prostatic portion of the urethra. The passage of the testicle and the presence of the spermatic cord leave a potential canal in the lower abdominal wall along which a portion of the intestine may run in forming an inguinal hernia. As the round ligament is the only structure in the female which oc- cupies this canal, the chance of this form of hernia is much lessened in women. 102 ANATOMY FOR NURSES f\ V( 9 THE THORACIC VISCERA The thorax is divided into two pleural and a cardiac space, each lined by serous membrane, and a space be- tween, the mediastinum, which transmits many impor- tant structuresT" The cardiac space is surrounded by a membrane, the fibrous pericardium, cone-shaped with its large end below, corresponding to the upper face of the central and left leaflets of the trefoil tendon of the diaphragm. Above the cone contracts to .blend with the fibrous coat of the great blood vessels attached to the heart. The pericar- dium lies between the lungs on either side, the sternum and left costal cartilage from the third to the seventh in front, and the vertebral column behind, from which it is separated by the root of the lungs, esophagus, and thoracic aorta. It is lined by a serous pericardium which covers its walls and the exterior of the heart and its vessels. The heart has its small end, or apex, directed down- ward and to the left, corresponding to the space be- tween the fifth and sixth ribs about three inches to the left of the midline. The base, directed backward, up- ward, and to the right, corresponds to the thoracic vertebrae from the fifth to the eighth inclusive. The exterior of the heart is marked by two furrows at right angles to each other. The upper furrow passes transversely around the organ, lodges a large venous and arterial channel and indicates the position of the septum between auricles and ventricles. The vertical groove passes to the right of the apex, lodges vessels and indicates the position of the interventricular septum. SPLANCHNOLOGY 103 The interior of the heart is divided into two upper cavities, the right and left auricles, and two lower, the right and left ventricles. The right side of the heart is the venous and the left the arterial. The right auricle receives the inferior vena cava at its lower and the superior vena cava at its upper part. These pour in the blood from all parts of the body ex- cept the heart, whose return circulation goes into the same cavity through the coronary sinus. The upper front portion is prolonged into a projection like a dog's ear, called the auricular appendix, which overlaps the aorta. The left auricle, situated behind and to the left of the right, also has an auricle which overlaps the pulmonary artery. The cavity receives the pulmonary veins, four in number. The two left often unite so as to leave but three openings for their entrance. Each auricle has a large opening through the auriculo-ventricular septum, by which blood is poured into the corresponding ven- tricle. The right ventricle occupies nearly the whole of the front of the heart. It terminates above in a cone which gives rise to the pulmonary artery, and receives, behind that point, the venous blood through the right auriculo- ventricular opening. The latter is guarded by a valve made up of three flaps, the tricuspid, to which are at- tached small tendons, chordae tendineae, the termination of little muscles, the papillary, which are attached to the walls of the ventricle and keep the valves from being forced into the auricle when the ventricle con- tracts. The opening of the pulmonary artery is guarded by three valves, shaped like half cups, called semilunar. 104 ANATOMY FOR NURSES The left ventricle makes up most of the back of the heart, though it forms the front of the apex. It has a left auriculo-ventricular opening guarded by a two napped valve, the bicuspid or mitral, which has chordae tendineae and columnae carneaa (papillary) just as on the right side. Behind and to the right of the pulmonary opening of the right, this ventricle gives origin to the aorta, which is guarded by three sernilunar valves like those in the pulmonary. The left ventricle has walls about twice as thick as those of the right. The right pumps blood into the lungs only; the left, throughout the body. The left auricle is also thicker than the right, but the difference is not so great. The two auricles contract to fill the ventricles. Then the bicuspid and tricuspid valves close to prevent flow- ing back (regurgitation) of blood into the auricles. The contraction of the ventricles drives the blood into the pulmonary artery and the aorta. Then the semi- lunar valves close to prevent regurgitation into the ven- tricles. Injury or disease of the valves will cause a leak and the heart has to grow in size and power to compensate the leakage. The Pleural Cavities and Lungs Each pleural cavity is the space between the ribs on the sides and behind and the pericardium internally. Each is a closed sac lined by the parietal pleura. The two sacs do not touch, though they are very close to- gether at the level of the second rib. Within these sacs the lungs move freely, covered by the visceral or pul- monary pleura, a reflection of the parietal. The cavities are cone-shaped, with the apices upward and extending SPLANCHNOLOGY 105 above the clavicle into the root of the neck. The left extends lower down than the right, because the liver pushes the diaphragm up on the right. The lungs correspond in shape to the pleural cavities. The left is slightly larger than the right, but is hollowed out on its inner side by the projection of the heart. The bronchi, two cartilaginous tubes formed by the bifurcation of the trachea, with the pulmonary arteries and veins, form the chief elements of the root of the lungs, which enters at a depression above the middle of the inner surface. These divide and subdivide un- til small air cells are formed around which the minute vessels are so arranged that the inspired air can ex- change its oxygen for the gases contained in the venous blood. The presence of this air causes the lungs to float in water. The apex of the lung projects into the neck two and a half inches above the first rib and is a blunt point. The base is deeply hollowed out by the dome-shaped dia- phragm. The outer surface is broad and convex, to conform to the inner face of the ribs. The anterior border is thin and sharp, to fit into the interval between the front of the pericardium and the back of the ster- num and ribs. The posterior border is round and thick to fill in the deep groove beside the vertebral column and on the front of the ribs behind the angle. The in- ner surface is concave to fit the pericardium. The Mediastinum The mediastinum is the irregular space between the pleurae. Draw a line from the junction of the first and second pieces of the sternum upward and backward to 106 ANATOMY FOR NURSES the lower border of the fourth thoracic vertebras. All the space above this line is the superior mediastinum. It contains the innominate artery, and its vein, thoracic part of the left corotid and subclavian arteries, parts of the trachea, esophagus, pneumo gastric and phrenic nerves and many other structures. The remainder of the interpleural space is subdivided into anterior, middle, and posterior mediastinal cavities. The anterior mediastinum is the space in front of the pericardium. The middle mediastinum is the pericardium and its contents. The posterior mediastinum is the space between the back of the pericardium and the front of the thoracic vertebras below the fourth. It contains the esophagus, descending aorta, thoracic duct, part of the pneumogas- tric nerves, azygos veins, etc. CHAPTER VI ARTERIES AND VEINS The circulation of the blood starts at the heart which is a four chambered pump, having two right and two left chambers. The right side is for venous blood and the left for arterial. Starting from the left lower chamber the great aorta curves upward about two inches, bends abruptly to the left for nearly three inches and then turns sharply downward to finally divides into tAvo branches near the fourth lumbar vertebra, its two branches going to the lower extremities and the pel- vis. As it starts it gives two branches to the heart and then, in its transverse part, a large branch which splits into two to supply the right half of the head and neck and the right upper extremity. A second branch of smaller size does the same work for the left side of the head and neck, while a third is for the left upper ex- tremity. The main aorta, between these branches and its bifurcation, (splitting in two) gives off the branches to the remainder of the body. The venous blood is poured into the upper right chamber of the heart by two vessels called cavae, supe- rior and inferior. The superior collects blood from the head, neck and both upper extremities; the inferior from the lower extremities, pelvis, and greater part of the abdominal contents and walls. Between these two a 107 108 ANATOMY FOR NURSES set of veins called azygos take same blood from the abdomen and more from the thorax. Veins are divided into two sets, superficial, such as are seen on the back of the hand, and deep which accompany the arteries of the same name. The course of the circulation is to pass away from the heart through the arteries and to return to the heart through the veins. There is no direct communication between an artery and a vein; but as the arteries get smaller, their coats get thinner until they terminate in very small thin vessels called capillaries through whose wall the gases in the blood can be given off to the tissue and the gases in the tissue can be taken up by the blood forming an exchange of gases just the reverse of that in the lungs. Roughly the lungs, removing injurious gases, take out C0 2 from the blood and replace it with ; while the tissues take out and give up C0 2 . Gradually the capillaries get thicker walls and unite with each other to form vein- lets, which again unite to form small veins, which again unite and so the process is repeated until only two veins remain superior and inferior venae cavas. The arteries, therefore, constantly grow smaller by dividing or giving off branches; and the veins grow larger as they approach the heart, by the union of two or more small veins and the reception of tributaries; that is the veins are like tracing a river from sources to mouth and the arteries like tracing the same from mouth to various sources. At two points, lungs and liver, there is a special arrangement of blood vessels so important as to require special study. Only that in the lungs will be now mentioned. ARTERIES AND VEINS 109 PULMONARY CIRCULATION All the blood in the body, at one time or another, is poured through the upper right chamber of the heart (the right or venous auricle), and descends from that into the chamber below right or venous ventricle. From this it is driven, by contraction of the ventricle through the pulmonary artery, which splits into right and left pulmonary arteries, into the lungs, when these arteries divide and subdivide as in other parts of the body, until their capillaries finally are placed in such relation to the air cells of the lungs that the exchange of gases alluded to above can take place. All the blood in the body thus passes through the lungs where it is oxygenated, but does not nourish the lungs, which must have blood like any other tissue, and get it from a set of bronchial branches coming from the aorta. This aerated blood is now returned to the heart through a set of veins called pulmonary which enter the upper left chamber or auricle of the heart, called the arterial auricle. The pulmonary circulation is thus a sort of loop or side track in the general circulation and pre- sents the anomaly of an artery carrying venous and a set of veins carrying arterial blood. From the left auri- cle the blood is poured into the left or arterial ven- tricle and thence is pumped through the aorta and its branches to the remotest parts of the body, whence it is returned through capillaries, veinlets and veins to the heart to start over the same process again. As, therefore, the arteries form a continuous set of tubes leading away from the heart, and the veins a continuous set leading back, it is obvious that if one wants to trace 110 ANATOMY FOR NURSES a substance in its course from or to a given part of the body, it is only necessary to know what vessels supply that part. If one could place a tag on a certain blood corpuscle and route it for the big toe, its course would be as definite as if it had a railroad track to guide it, and like that would be capable of interruption or mis- carriage at various branch lines. It would leave the heart at the aortic opening, pass through the various parts of the aorta to its bifurcation where it would enter a primitive iliac artery and proceed through an external iliac, femoral and popliteal to the bifurcation of the latter, thence through the anterior tibial and dorsalis pedis to the great toe. Now it would have the choice of two routes for its return. If it went by the deep vein, it would start by a satellite accompanying the dorsal artery of the foot, through an anterior tibial, popliteal, femoral, external and common iliac into the inferior vena cava and thence into the venous auricle, venous ventricle, pulmonary artery, right or left lung as the case might be, back to the arte- rial auricle through a pulmonary vein, thence to the arterial ventricle and be ready at the mouth of the aorta to start on the same journey or be routed to the little finger, the eye, ear, brain or any other part of the anatomy. Its second route from the big toe would be to choose a veinlet of a long vein called internal saph- enous, which would conduct it along the inner side of the foot, ankle, leg and thigh until it pierced the fascia lata just below Poupart's ligament to empty into the femoral vein, after which its course would be the same as that just traced. It is, therefore, plain that the study of the arteries and veins is, in no inconsiderable meas- systemc Fig. 12. Diagram of entire circulation. ARTERIES AND VEINS 111 ure, merely a learning of names and not of facts; and that a knowledge of the parts formed by the skeleton will, in the main, furnish the student with the names. The two coronary arteries, for the supply of the heart itself, would spring just after the origin of the aorta; then would come the innominate which quickly subdi- vides into the right common carotid, going upward, and the right subclavian going outward. The left sub- clavian has a separate origin (the third) from the trans- verse aorta, and has a thoracic portion similar to the innominate. Getting to the middle of the clavicle, each subclavian becomes the counterpart of the other and the right only will be traced. From the inner end of the collar bone to its outer third the artery and vein are called subclavian; from there to the surgical neck of the humerus, axillary ; from there to the bend of the elbow the artery is the brachial, but there are two brachial veins, one on each side. At the bend of the elbow, in other words as soon as there are two bones, the artery bifurcates and the two are known as radial or ulnar according as they are found on the inner or outer bone. They continue under these names into the hand Avhere they communicate, and each has two veins. From the bifurcation of the aorta the names are to the brim of the pelvis common or primitive iliac which divides into an internal iliac for the pelvis and an ex- ternal for the lower extremity, which changes its name at Poupart's ligament to become femoral and that be- comes popliteal at the lower third of the femur and divides into anterior and posterior tibial just below the knee joint. These pass down on 'the front and back of the leg respectively, and are distributed to structures 112 ANATOMY FOR NURSES as they descend, the anterior becoming the artery of the back of the foot (dorsalis pedis), while the posterior divides into internal and external plantar arteries for the sole. The right and left carotid arteries, above the clavicle, pass np to the thyroid cartilage and divide into the internal and external carotids, the internal to enter the skull through an opening in the temporal bone and sup- ply the interior of the skull and its contents ; while the external, dividing into temporal and deep facial, or inter- nal maxillary, supplies the interior of the skull and face. THE AORTA The aorta extends from the base of the heart to the lower border of the fourth lumbar vertebra and is di- vided into ascending, transverse and descending, the lat- ter having a thoracic and an abdominal portion. The Ascending Aorta The ascending aorta, about two inches long, lies a quarter of an inch behind the sternum, in the pericar- dium, overlapped by the right auricular appendix and having the pulmonary artery first in front and then to its left. It terminates by becoming the transverse aor- ta at the upper border of the second right costal car- tilage, where the aortic valves may be heard, where the pericardium blends with the outer coat of the vessel. It gives off the two coronary arteries, right or an- terior and left or posterior. They descend in the cor- responding interventricular grooves and anastomose at the apex of the heart, after giving off lateral ARTERIES AND VEINS 113 branches at the auriculo-ventricular grooves which em- brace the heart transversely and inosculate with each other. The Transverse Aorta The transverse aorta, starting at the upper second right cartilage, passes backward, downward, and to the left to the lower border of the fourth dJifel vertebra where it becomes the descending aorta. It lies in the superior mediastinum about an inch below the sternal notch and is overlapped greatly by the left pleura and lung. Across its upper front runs the left innominate vein, the left tenth and phrenic nerves, w r hile behind it is in close contact with the trachea, esophagus, tho- racic duct and left recurrent laryngeal nerve. The bi- furcation of the pulmonary artery is below it. It gives off, from its upper side, from right to left the arteria innominata, left common carotid, and left sul)- clavian. The Thoracic Aorta The thoracic aorta begins at the lower border of the fourth and terminates on the body of the twelfth dorsal vertebra by becoming the abdominal aorta. It lies in the posterior mediastinum at first on the left side and then 011 the front of the vertebrae, inclining forward and to the right. The esophagus, bearing the two tenth (pneumogastric) nerves, crosses it obliquely in front, as does the root of the left lung. The vena azygos major and thoracic duct are to its inner side. It is nearly covered by the left pleura and lung. In front, below the fifth vertebra, lies the pericardium and heart. 114 ANATOMY FOR NURSES Branches. These are bronchial, intercostal, pericardiac, eso- plwgcal and mediastmal. The last three are small twigs given the structures whose names they bear. The bronchial arteries pass outward in the root of the lungs and supply the substance of those organs. The intercostal arteries are ten pairs 'which run in the inter- costal spaces, except the upper, to supply the ribs and structures adjacent to them, and to anastomose with branches of the internal mammary in front. * The Abdominal Aorta The abdominal aorta begins on the body of the twelfth thoracic vertebra and terminates, greatly di- minished, on the body of the fourth lumbar by dividing into right and left common iliacs. This artery passes through the aortic opening be- hind the diaphragm, rests on the bodies of the vertebras and lies behind the peritoneum and many of the abdom- inal viscera. It has the stomach in front, but dis- tant, the pancreas and transverse duodenum in imme- diate contact, and the transverse colon in front and dis- tant. On its right side, throughout, is the inferior vena cava while the mesentery of the small intestine is at- tached obliquely across it. The left lumbar veins run behind and the' left renal in front. Branches. The branches, numerous and important, are divided into parietal and visceral. The parietal branches are phrenio, lumbar, and sacra media. The phrenic are just muscular branches, for the diaphragm. They sometimes come from one of the branches of the aorta, ram- ify over the diaphragm and inosculate with each other and with the mUjSCulo-phrenic of the internal mammary. The lumbar are four pairs which correspond to the intercostals. They have no intercostal spaces in which to run, but spread out in the broad muscles of the abdomen, supplying them and inosculat- Fig. 13. The aorta and its branches. tfl ARTERIES AND VEINS 115 ing with a branch of the external iliac which corresponds to, and anastomoses with, the internal mammary. The sacra media is a small vessel running down the sacrum. The remaining branches are divided into digestion and genito- urinary. ! [j In the first set are the oelmc axis, superior and inferior mes- enteric, while the second comprises the renal and suprarenal, the spermatic in the male, and ovarian in the female. The Celiac Axis The celiac axis is a short trunk springing from the aorta immediately after it pierces the diaphragm juts forward and breaks up into three branches, gastric, he- patic, and splenic. The gastric reaches the lesser curvature of the stom- ach by passing up behind that organ and then runs to the right to meet the pyloric from the hepatic and form a loop along the upper part of the stomach from which small branches run down both its faces. The hepatic runs first to the right and then upward in the lesser omentum to the under surface of the liver where it divides into right and left hepatic arteries for the two lobes of the liver to which it supplies arterial blood. It has the bile duct on its right and the portal vein between and behind duct and artery. It gives off a branch to the gall bladder and a large branch which, after aiding in the supply of duodenum and pancreas, runs to the left in the great omentum along the great curvature of the stomach to meet a sim- ilar branch of the splenic and form a loop which gives ascending branches to both faces of the stomach and descending branches to the omentum. These arteries are called gastro-epiploica dextra and sinistra (arteries of the stomach and omentum, right and left). 116 ANATOMY FOR NURSES The splenic is the largest branch of this axis. It runs along the upper border of the pancreas behind the stom- ach, to the spleen with the splenic vein below it and be- hind the pancreas. Most of its blood is poured into the spleen (a blood elaborating gland), but it gives large branches to the pancreas and great end of the stomach (vasa brevia) in addition to the gastro-epiploica sin- istra. The Superior Mesenteric The superior mesenteric is a very large vessel which supplies the intestinal canal from the duodenum to the middle of the transverse colon. It arises just below the celiac axis, behind the pancreas, runs between that gland and the transverse duodenum into the mesentery and thence, with a decided curve, convex to the left, passes to the right iliac fossa. It is accompanied by a vein lying to its right and, as the mesentery moves freely, is the most movable artery in the abdo- men. Branches. This artery is distributed by a number (eight to eighteen) of branches from its convex left side called vasa intestini tennis, and by three branches on the right named, from below up, ileo-colic, colica dextra and calica media, besides a small branch to the pancreas and duodenum which inosculates with a similar branch derived from the hepatic. The vasa intestini tenuis are all distributed in the same way. Each divides, after a short course, into an upper and a lower branch. The upper of one and the lower of the other run to- gether and form a loop. From these loops branches spring which divide and unite to form a second loop, and from this another loop may be formed. There are usually three series of loops, each smaller than its predecessor, though sometimes more. From the last loop spring branches (vasa recta) which do not divide but run, one in front and the other behind, around the intestine and anastomose with each other in its w r alls. Fig. 14. Superior mesenteric artery. ARTERIES AND VEINS 117 On the concave side the distribution is similar but not identi- cal. The ileo-colic splits into two of which the lower joins the last of the intestini tenuis and the upper the lower of the two from the colioa dextra which divides into two, the lower to the ileo- colio and the upper the right branch of the colica medM, whose left branch joins the upper branch of the colica sinistra, a branch of the inferior mesenteric. No secondary loops are formed from these anastomoses but straight branches are at once given off to the large intestines. The Inferior Mesenteric The inferior mesenteric, much smaller than the su- perior, arises near the termination of the aorta on its left side. It passes to the left, behind the peritoneum, gives off a colica sinistra whose upper branch passes to the right to meet the colica dextra on the transverse colon, while the lower passes to the descending colon and anastomoses with the highest sigmoid branches. The sigmoidea are several branches the highest inosculating with the lower of the sinistra, the lowest with the superior hemorrhoidal and supplying the sigmoid flexure. ^The superior hemorrhoidal is the termination of the inferior mesenteric and supplies the upper part of the rectum and anastomoses with hemorrhodial branches from the internal iliac. Summary The abdominal alimentary canal is supplied with blood as follows: The stomach and duodenum by the gastric and branches from the hepatic and splenic and superior mesenteric ; the jejunum and most of the ileum by the vasa intestini tenuis ; the lower part of the colon and up to the middle of the transverse colon by the branches from the right side of the superior mesenteric, and 118 ANATOMY FOR NURSES the remainder to the lower part of the rectum, by the inferior mesenteric. THE PORTAL CIRCULATION Each of the arteries described above, except the he- patic, is accompanied by a vein of the same name, formed by veinlets which ramify in the corresponding organs. The inferior mesenteric vein empties into the superior; the superior joins the splenic to form the portal ; the gastric veins join the splenic before it reaches the superior mesenteric. The portal vein, therefore, receives blood which comes from the abdominal intestinal tract from the be- ginning of the stomach to the middle of the rectum in- clusive. This embraces all the digestive tract, the spleen, and the pancreas. This blood, charged with the products of digestion in addition to the ordinary con- tents of venous blood, enters the liver with the hepatic artery, breaks up into branches of ever diminishing size to ramify throughout that organ and then form vein- lets which collect the blood again until they unite to form the hepatic veins which ultimately pour this great volume of blood intoHi^ inferior vena cava just before it emp%ies--mtG 4he -heart. \JO^JL < THE GENITO-URINARY ARTERIES These vessels are the renal, suprarenal and spermatic or ovarian. The renal arteries are short large vessels, the right the larger, which pass outward to the hilum of the kid- ney, one on each side, where they break up into three ARTERIES AND VEINS 119 branches, one to each third of the organ. They lie be-^ hind the peritoneum with the renal vein in front and the ureter behind. The suprarenals are small wigs, often springing from the renal, for the suprarenal gland. The spermatic is a long slender vessel rising just be- low the renal which leaves the abdomen through the inguinal canal, with, other elements of the spermatic cord, and is distributed to the testicle. The ovarian arteries are analogous to the spermatic. They pass over the beginning of the external iliac ar- try, run in the folds of the broad ligament and are dis- tributed to the ovaries. ARTERIES OF THE HEAD AND NECK Three branches spring from the top of the transverse aorta, innominate, left common carotid, arid left sub- clavian. The innominate combines the right common carotid and subclavian. The Innominate Artery The vessel springs from the beginning of the trans- verse aorta and passes upward and to the right through the superior mediastinum to the sterno-clavicular ar- ticulation where it divides into the right common carotid and right subclavian arteries. On its outer side is its own vein, across its front the left innominate vein, inter- nally the left common carotid and, behind and inter- nal, the trachea. The right lung and pleura ovelap it. The Left Common Carotid This artery lies with the innominate on its right and left subclavian on its left and slightly behind. It is 120 ANATOMY FOR NURSES crossed by the left innominate vein, has the trachea and esophagus behind and internal, the left pneumogastric and phrenic nerves to its outer side, and the recurrent laryngeal first behind and then internal. Its thoracic portion stops at the sterno-clavicular articulation and the cervical portion, which is like the right, needs no description. The Left Subclavian The thoracic portion of the left subclavian extends from near the end of the transverse aorta to the inner border of the scalenus anticus muscle. It is nearly in- vested by the left pleura and lung. The left carotid is internal, the left innominate vein crosses in front high up, the phrenic nerve is in front, the pneumogastric an- tero-internal and the thoracic duct behind and internal. The last three vessels are behind the sternum and are in relation with the structures attached to that bone. The Cervical Carotids The common carotids in the neck lie on the group of muscles covering the transverse processes as high as the fourth, on a level with the upper border of the thyroid cartilage, where they divide into internal and external carotids. They are in a sheath formed by the deep cer- vical fascia, in which are the internal jugular vein and the pneumogastric nerve. They are deeply seated at the root of the neck where they are covered by the muscles attached to the sternum, but become more su- perficial as the muscles draw away above. The pla- tysma, deep cervical, fascia, and skin cover them throughout. The sterno-cleido-mastoid covers them be- low and overlaps them above. Its inner border is the ARTERIES AND VEINS 121 guide to the vessels. The internal jugular vein is ex- ternal, the pneumogastric nerve between artery and vein, descendens hypoglossi on the front of the sheath, and the cervical sympathetic behind it. Internally are the larynx, above, and trachea below. No branches arise from these vessels. The External Carotid The external carotid is the smaller of the terminal branches of the common carotid. Beginning at the up- per border of the thyroid cartilage it terminates 'be- hind the neck of the lower jaw by dividing into the temporal and internal maxillary. It is covered by the skin, fascia and platysma and overlapped, at first, by the sterno-mastoid. The digastric muscle crosses its front and is used by surgeons to divide it into three parts. It is crossed by the twelfth nerve and has the ninth nerve and superior laryngeal behind it. Its upper part is imbedded in the parotid gland. Internally is the pharynx. Branches. These are seven in number, superior thyroid, lin- gual, facial, occipital, posterior auricular, ascending pharyng&al, and parotidean. Their names indicate the parts supplied. The superior thyroid goes to structures around the thyroid car- tilage and inosculates with its fellow of the opposite side and with an inferior thyroid from the subclavian. The lingual goes to muscles attached to the hyoid bone, but chiefly to the tongue. The facial gives large branches below the lower jaw, runs tortuously across the face from an inch in front of the angle of the jaw, where its pulsation can be felt, to the inner angle of the eye where it inosculates with a branch from the internal carotid. It supplies the chin, lips, cheeks, and nose in part. The occipital winds beneath the mastoid process of the tem- poral to reach the back of the skull where it inosculates with 122 ANATOMY FOR NURSES its fellow of the opposite side and, in front, with the posterior temporal. It supplies the back part of the scalp and gives one large muscular branch in the neck (princeps cervicis) which runs downward and establishes a communication with a branch of the subclavian. The posterior auricular is distributed to the back of the ear. The pafotidean are four or five small branches for the parotid gland. The a-scending pliaryngeal, coming off near the origin of the carotid, passes up the neck to the pharynx and by one branch, to the membrane of the brain. The Temporal Artery The temporal is the smaller of the terminal branches of the carotid. It mounts over the zygoma and gives off branches which supply the front of the ear, the side of the face, the temporal muscle and the middle por- tion of the scalp, inosculating in front with the frontal, derived from the internal carotid, and behind with the occipital. The Internal Maxillary The internal maxillary, much larger than the tem- poral, turns inward and forward from the neck of the lower jaw to run finally into the space between the sphenoid and superior maxilla. Its work is to supply the deep structures of the face, including the teeth, and the membranes of the brain. Branches. A small branch enters the ear while a much larger, meningea media, passes to the middle fossa of the skull through a hole in the sphenoid, and, ramifying between the bone and dura, grooving the bones deeply, is the chief artery of the dura. The inferior dental runs in a tunnel in the lower jaw and gives a branch to every fang of every tooth as it passes, finally emerg- ing on the chin to inosculate with the facial. The muscular branches are distributed to the muscles of mas- tication. ARTERIES AND VEINS 123 Superior dental brandies supply the teeth of the upper jaw, while an infraorbital emerges from a tunnel beneath the floor of the orbit to appear on the face and communicate with the facial. Other branches supply the palate, nose, pharynx and eustachian tube. . The face is very abundantly supplied with blood. Arteries come to it from various sources and inosculate with great free- dom. It is nearly impossible to cut off collateral circulation 1 and these tissues will survive injuries which would destroy many others. The Internal Carotid The internal carotid continues the course of the com- mon carotid upward to the base of the skull where it enters a foramen in the petrous part of the temporal bone, runs forward and inward in a tunnel in that bone, turns upward in the middle fossa of the skull and terminates by dividing into an anterior and middle cere- bral, posterior communicating and anterior choroid. This vessel is deeply seated and in relation with many important structures, very important to the surgeon but of little use to the nurse. The internal jugular vein lies on its outer side, the tenth nerve lies between vein and artery and the ninth, eleventh and twelfth nerves all bear relations to it. The sympathetic is behind. Branches. The distribution of these is largely to the brain and can not be comprehended until the brain is studied. The ophthalmic is distributed to structures in and around the orbit. It comes off near the end of the artery, enters the oroit through the optic foramen and breaks up into nearly a dozen branches. These are distributed to the eyeball (cMiary}, retina, eyelids (palpebral) , lachrymal gland, nasal cavity and ethmoidal cell while two branches, the supraorbital and frontal pass out of the orbit to the front of the scalp which they nourish and where 124 ANATOMY FOR NURSES they communicate with the temporal, with each other and with the vessels of the opposite side. ARTERIES OF THE UPPER EXTREMITY The Subclavian The cervical subclavian extends on the right from the bifurcation of the innominate at the sterno-clavicular joint to the outer border of the first rib; on the left from the inner edges of the scalenus anticus to the outer border of 'the left first rib. The first and second parts of the right subclavian are deeply seated, covered by skin, fascia, platysma, sterno- mastoid, while the outer third of each is superficial, having only skin, fascia and platysma as coverings. The apex of the lung is under the subclavian in its first two parts. The pneumogastric and phrenic nerves cross it in front with the internal jugular vein, which unites with the subclavian to form the right innomi- nate. The artery is bent like a bow; the vein runs straight and only touches the artery at its inner and outer ends. The recurrent laryngeal nerve winds from front to back. The brachial plexus of nerves comes in contact with the artery in its second part and lies above and somewhat posterior. Branches. These are the vertebral, thyroid axis breaking into the inferior thyroid, suprascapular and transverse cervical; the internal mammary, superior intercostal and profunda cervicis. The vertebral enters the foramen in the transverse process of the sixth cervical, passes through these foramina in succession, giving off branches to the spinal canal and its contents, enters the skull through the foramen magnum and joins the opposite vertebral to form the basilar whose distribution is taken up with the arteries of the brain. ARTERIES AND VEINS 125 The inferior thyroid is distributed to the thyroid gland and muscles of the neck, inosculating with the superior thyroid and the opposite artery. The suprascapular passes outward across the third part of the subclavian, accompanied by its vein, and \& distributed in the supraspinous and infraspinous fossae. The transverse colli runs across the neck and breaks into two branches, the upper to anastomose with the occipital and the lower to run along the vertebral border of the scapula, com- municating with the suprascapular and subscapular. The internal mammary runs down the thorax behind the costal cartilages about half an inch from the sternum to the diaphragm where it divides into the superior epigastric and musoulo-phrenic. It gives off anterior intercostals to the intercostal spaces, a branch to the phrenic nerve, mediastinal and pericardiac and six anterior perforating branches which run between the ribs to the muscles of the chest and the mammary gland. They are larger and more important in the female than, in the male. The superior epigastric passes down in the rectus muscle to inosculate with an inferior epigastric of the external iliac. The inusculo-phrenic gives off intercostal branches to the lower spaces and muscular branches to the diaphragm. The superior intercostal and profunda cervicis usually rise by a common trunk, the former supplying the first intercostal space and the latter anastomosing with a Branch of the occipital. The Axillary The axillary begins behind the outer third of the clavicle, on the outer border of the first rib, as a contin- uation of the subclavian, and passes through the outer angle of the axilla to become the brachial at the lower border of the teres major. It is covered by the pectoral muscles, rests on the sub- scapularis and tendons of the latissimus dorsi and teres major, has the serratus magnus internal and the short head of the biceps and the coraco-brachialis external for the lower part. The axillary vein is internal and in front throughout. The brachial plexus lies external 126 ANATOMY FOR NURSES and behind at first, breaks into three cords which lie behind, external and internal behind the pectoralis minor and gives off its terminal branches which surround the artery just below that muscle and then lie on three sides, inner, outer, and posterior. Branches. These are very irregular. One, superior thoracic, supplies the pectoral muscles; one, acromial thoracic, the deltoid and other structures around the acromion. The long thoracic goes to the chest wall and the alar thoracic to the structures in the axilla. The anterior and posterior circumflex, the latter much the larger, surround the surgical neck of the humerus and supply it, the deltoid, and the shoulder. The subscapular, the largest branch, supplies the subscapular fossa, part of the inf raspinous and the muscles attached to these and the axillary border of the scapula. The Axilla This is a wedge-shaped space between the upper five ribs internally, the bicipital groove of the humerus ex- ternally and the scapula behind. Its apex is above. The pectoral muscles form its anterior wall, the serra- tus magnus the internal and the subscapularis teres major and latissimus dorsi its posterior. The outer angle ends in the bicipital groove between the anterior and posterior walls. The floor is formed by the invest- ing fascia stretching from the anterior to the posterior folds. The outer angle is filled by the axillary vessels, nerves, and lymphatics, which follow the course of the vessels, while the inner and lower part contains a con- siderable amount of fat. The Brachial The brachial is a continuation of the axillary and terminates a ' ' fingersbreadth ' ' below the bend of the Axillary artery and vein V. cephalic A. radical A. and V. post, interosseous A. anastomotica magna Princeps pollicis A. and V. post, circumflex . and V. ant. circumflex A. ulna A. and V. ant. interosseous Sup. palmar arch -Palmar collateral digital Fig. 15. Diagram of arteries and veins of upper extremity. ARTERIES AND VEINS 127 elbow by dividing into radial and ulnar. It is super- ficial, covered only by skin, superficial and deep fas- cias, overlapped by the biceps from the outer side and easily compressed against the bone outward and back- ward above, and backward below. Unlike the corre- sponding vessel of the lower extremity (popliteal) it has satellite veins, one on each side. The median nerve is first external, then in front and finally internal. The basilic vein and internal cutaneous nerve are in the fas- cia which covers it antero-internally. Branches. The superior profunda winds through the musculo- spinal groove to supply muscles on the back of the arm and aid in the vascular circle around the elbow. The inferior profunda passes to the inner side of the elbow. The anastomotica magna runs transversely around three-quar- ters of the joint from the inner side, and is the chief agent in forming the anastomoses. Muscular branches are also given off. The Radial The radial runs down the outer side of the forearm to the styloid process where it turns backward across the carpus to the first interosseous muscle through which it plunges to form the deep palmar arch. The brachio-radialis muscle lies external to this artery and is the guide to it. Internally the flexor carpi radialis is the chief relation. Between the two the lower part is superficial and is the artery most fre- quently used to feel the pulse. The artery has satellite veins and the nerve is external in the middle. Branches. A recurrent branch aids in the anastomoses around the elbow. Muscular twigs supply the outer side of the forearm. 128 ANATOMY FOR NURSES The Ulnar The ulnar is larger than the radial and more deeply seated. It runs under the muscles of the superficial group, except one, flexor carpi ulnaris, which lies to its inner side, and enters the palm to the outer side of the pisiform to form the superficial palmar arch. It, too, has satellite veins and its nerve internal for its lower two-thirds. Branches. Two recurrent branches enter the elbow circle. The interosseous is a short trunk breaking into a large anterior and a small posterior interosseous. The anterior descends on the interosseous membrane, supplying muscles in its course, and, piercing the membrane below, aids in forming the carpal arch. The posterior passes above the interosseous membrane and is mainly a muscular vessel for the back of the forearm, but a twig gets to the carpal arch. Arterial Supply of the Hand Draw a line from the top of the web between thumb and index finger and the superficial palmer arch is roughly represented. This is formed by the continua- tion of the ulnar joining a branch of the radial. It lies on the flexor tendons and ulnar and median nerves. From the arch thus formed branches pass to the clefts between the fingers and divide into a branch for the adjacent sides of the fingers. These are called palmar collateral digital branches and not only anastomose with the branch of the opposite side of the finger, but with those on the back as well. The branch to the thumb comes entirely from the radial and is called princeps pollicis. The deep arch lies higher up on the carpus and under the tendons. It is formed chiefly by the radial with a ARTERIES AND VEINS 129 communication from the nlnar. Its branches go to the carpus, perforate the spaces to pass to the back of the metacarpus, and give interosseous branches which join the palmar digital. A posterior carpal arch is formed by small branches from the radial and ulnar and this with three branches, dorsales pollicis and dorsalis indicis supply branches to the back of the hand and fingers. ARTERIES OF THE PELVIS AND LOWER EXTREMITY Common Iliac The common iliac arteries are terminal branches of the abdominal aorta, beginning on the fourth lumbar vertebra and diverging to reach the disc between the 1 fifth lumbar and sacrum w T here they bifurcate to form the external and internal iliac arteries. These vessels lie behind the peritoneum and viscera, and each vein is right of its own artery, but the left vein crosses behind the right artery in order to join the right vein and form the inferior cava. There are no branches. The Internal Iliac The raternal-iliac carries blood to the walls and vis- cera of the pelvis. It drops over the pelvic brim, runs down on the sacro-iliac joint to the sacro-sciatic notch and divides there into an anterior and posterior trunk. It lies behind the peritoneum with the ureter in front and the lumbosacral cord behind. 130 ANATOMY FOR NURSES Branches. From the anterior trunk come branches for the bladder (vesical) and rectum (heniorrhoidal) an obturator and two terminal branches, internal pudic and ischiatic, and, in the female, uterine and vaginal branches. The uterine passes to the neck of the uterus, runs up on the side and joins the ovarian artery. The vaginal takes the place of the inferior vesical in the male. The obturator crosses the pelvic wall, with its nerve above and vein below, to the upper part of the obturator foramen through which it leaves the pelvis to be distributed to muscles of the gluteal and adductor groups and to the hip joint. The ischiatic leaves the pelvis through the great sacro-sciatic foramen and runs down the back of the thigh as far as the knee, giving off branches to muscles of that region. The internal pudic, or pudendal, artery leaves the pelvis through the great sacro-sciatic foramen to reenter through the lesser, run along the ischio-pubic rami and end in the external genital organs. It gives a branch to the skin of the perineum, one to the back of the penis, one to the carpus spongiosum and one to the cavernosum. In the female these branches are very small and go to analogous parts. The posterior trunk gives off the ilio-lumbar which does the work of a lumbar artery and in addition, supplies the iliac fossa ; a lateral sacral, which gives a branch to each anterior sacra] foramen and terminates in the gluteal, a large artery which leaves the pelvis above the pyriformis, supplies muscles of the gluteal region and aids in forming the anastomoses around the hip joint. The External Iliac The external iliac begins at the fifth lumbar disc and terminates under the middle of Poupart's ligament by changing its name to femoral. It is behind the peri- toneum, has its vein internal, the psoas magnus external and the ovarian artery in front, in the female, on both sides. The right is overlapped by the cecum and often crossed by the appendix. The left has the sigmoid flexure lying on it. A. sup. ext. articular A. inf. ext. articular i ! A. ant. recurrent tibial 1 ' A. femoral -A. profunda femoris -A. internal circumflex A. external circumflex -A. first perforating -A. second perforating -A. third perforating -A. anastomotica magna -A. popliteal -A. sup. internal articular | I * A. inf. int. articular -A. ant. tibial -A. post, tibial A. peroneal A. ant. peroneal A. ext. malleolar A. A. ext. calcaneal | A. ext. plantar- A. int. malleolar F A.A. int. calcaneal A. dorsalis pedis I A. int. plantar A. metatarsal A. communicating Fig. 16. Diagram of arterial circulation in lower extremity. Bi.r.-n.nV ARTERIES AND VEINS 131 Branches. These are two, deep epigastric and deep circum- //( ./ iliac. The deep epigastric runs upward in the sheath of the rectus, gives off muscular branches, and anastomoses with the internal mammary. The deep circumflex iliac courses along Poupart's ligament and the crest of the ilium, gives branches to the broad muscles and anastomoses with the lumbar and gluteal arteries. The Femoral The femoral runs from a point midway between the anterior superior spine of the ilium and the symphysis pubis across the front and inner side of the thigh to its lower third, where it turns to the back and becomes the popliteal. It is superficial above, lying in a space, Scarpa's triangle, bounded above by Poupart's liga- ment, externally by the sartorius internally by the ad- ductor behind. Its vein is internal and abreast at first but gets longer and then external. The anterior femoral nerve is a quarter of an inch to its outer side. Two inches below its origin it gives off from its outer side, the profunda femoris which quickly gets behind with its own vein in front of it. So that femoral artery, femoral vein, profunda vein, profunda artery would be the order from before backward. Branches. Besides several superficial branches to the pubic region, lower abdomen, space around the anterior spine of the ilium, and muscular branches, this artery gives off the anasto- motica magna at its lower portion to partly encircle the femur and form a great portion of the vascular zone around the knee joint. The profunda femoris carries the greater part of the blood of the thigh. It gives off external and internal circumflex branches, the external the larger, which en- 132 ANATOMY FOB NURSES circle the upper part of the femur, aid greatly in the anastomoses around the hip joint and supply muscles of the thigh. The three perforating arteries come from the profunda on the adductor muscles, which they perforate to appear at the back of the thigh. The Popliteal The popliteal extends from the lower third of the femur, across the back of the knee joint, to the upper fifth of the tibia where it divides into anterior and pos- terior tibial arteries. It lies on the femur, posterior lig- ament of the knee and popliteus muscle and is sur- rounded by the muscles bounding the popliteal space. Its vein, which hugs the artery closely, is behind and the internal popliteal nerve is behind the vein. They cross the artery obliquely and are a little external above and a little internal below. Branches. Muscular branches, above and below the joint, are given to the hamstring muscles and heads of the gastrocnemius, besides five articular arteries, two above, two below, and one in the middle, supplying the joint. They communicate with each other, the anastomotica magna and recurrent branches from the tibia. The Anterior Tibial The anterior tibial passes between the leg bones and runs down the interosseous membrane, between mus- cles of the anterior group to the middle of the ankle, beneath the annular ligament, where it changes its name to dorsalis pedis which continues the artery to the base of the big toe. It is accompanied by satellite veins and its nerve which is antero-external. ARTERIES AND VEINS 133 Branches. A recurrent branch joins the knee circle. Muscular branches supply the tibial group, and external and internal mal- leolar form a large part of the ankle circle. The Posterior Tibial The posterior tibial, larger than the anterior, runs down between the deep and superficial groups on the back of the leg to midway between the inner malleolus and the heel where it divides into the internal and ex- ternal plantar arteries. It is accompanied by satellite veins and its nerve which is internal at first but quickly crosses it behind to remain external to the end. At the ankle it lies between the tendon of the flexor longus digitorum internally and the longus pollicis externally. Branches. Besides muscular and internal calcanean, distrib- uted around the inner aspect of the heel and ankle, it gives a large branch high up called peroneal. The peroneal corresponds to the posterior interosseous of the uliiar. It descends to the lower part of the leg, gives off a large anterior peroneal branch and itself runs to the outer side of the heel as the external calcanean. Arterial Supply of the Ankle and Foot The malleolar and calcanean arteries communicate with each other and with branches of the plantar and dorsalis pedis arteries to form the annular zone around the ankle. / . The e^^Safplantar artery corresponds to the super- ficial palmar arch, supplies the three and a half outer toes and anastomoses with a communicating branch of the dorsalis pedis, which supplies the big toe and inner half of the second. The ifiecteS plantar is chiefly a muscular branch for the inner part of the sole. 134 ANATOMY FOR NURSES The dorsalis pedis supplies the back of the great toe and half the second. The remaining toes are supplied dorsally by interosseous branches from the metatarsal branch of the dorsalis pedis. THE VEINS The veins are divided into superficial, lying in the su- perficial fascia, and deep, accompanying the arteries. Some channels in the skull, called sinuses, perform the functions of veins. THE VEINS OF THE LOWER EXTREMITY The superficial veins of the lower extremity are the long and short sapheiious. They are abundantly pro- vided with valves which enable the vertical columns of blood to overcome gravity. The Long Saphenous Just back of the web of the toes a venous arch is formed across the dorsum of the foot which receives tributaries from the toes and gives rise to the long saphenous vein on the inner side of the foot. It runs across the front of the inner malleolus, up the inner side of the leg to the back of the inner condyle, re- ceives a communication from the short saphenous, con- tinues up the inner face of the thigh, receiving tribu- taries all the way, reaches the saphenous opening in the fascia lata Avhere it receives the veins accompanying the superficial branches of the femoral artery, and emp- ties into the femoral vein. ARTERIES AND VEINS 135 The Short Saphenous The short saphenous begins at the outer side of the dorsal arch passes around the outer malleolus to the calf, up the middle of which it runs to the popliteal space, where, after giving a communication to the long saphenous, it empties into the popliteal vein. Deep Veins of the Lower Extremity Metatarsal veins unite to form satellite veins for the plantar arteries. The two inner and the two outer plantar veins unite to form the satellites of the posterior tibial, which unite with those of the anterior tibial to form the popliteal. This accompanies the popliteal artery to the lower third of the thigh where it becomes the femoral ; follows that artery to two inches below Poupart's liga- ment, where it receives the deep femoral, then the long saphenous and passes under Poupart's ligament to be- come the external iliac. The external iliac receives the epigastric and circum- flex iliac veins and joins the internal iliac to form the common iliac. The two common iliacs unite at the fifth lumbar disk on the right side and form the inferior vena cava which passes through the diaphragm op- posite the ninth dorsal vertebra and empties into the right auricle of the heart. THE VEINS OF THE UPPER EXTREMITY These are also superficial and deep and are provided with valves. The deep and superficial anastomose fre- quently. 136 ANATOMY FOR NURSES The Superficial Veins of the Upper Extremity A network of veins is formed on both surfaces of the hand, though more apparent on the back. Near the wrist a vein called median begins and passes up the middle of the front of the forearm until just below the elbow where it divides into the median cephalic exreraally and the median basilic irri!ew*alr$ The veins on the outer side of the hand give rise to a superficial radial vein which courses up the outer side of the forearm to join the median cephalic and form the cephalic. This vein passes up the outer side of the arm, runs into the groove between the deltoid and pectoralis major muscles, and empties into the axil- lary vein just below the clavicle. There are two ulnar veins anterior and posterior which run up the front and back of the inner part of the forearm. They unite to form the common ulnar an inch or more below the elbow joint and this joins the median basilic to form the basilic vein. The basilic vein runs up the inner side of the arm, pierces the in- vesting fascia and joins the brachial satellites (the inner usually) to form the axillary. The deep veins begin as satellites of the superficial and deep arches, receive digital and metacarpal veins, form satellites of the radial and ulnar arteries which in turn, after the ulnar receives the interosseous satellites, unite to form the brachial satellites which either unite and join the basilic, or the inner joins the basilic and receives the outer, to form the axillary. The axillary vein accompanies the axillary artery, receives the numerous tributaries which follow ARTERIES AND VEINS 137 branches of that vessel, is joined by the cephalic just below the clavicle and becomes the subclavian. The subclavian vein touches its artery only at its ends. It receives the external jugular vein in addition to the veins accompanying the branches of the sub- clavian artery and also the thoracic duct on the left and right lymph duct on the right, just at its junction with internal jugular to form the innominate. THE VEINS OF THE HEAD AND NECK The veins of the brain and its membranes empty into channels in the dura called sinuses. The chief sinuses are the superior and inferior longitudinal, the straight, the occipital, lateral and petrosal. Many of these meet at the anterior occipital protuberance and pour their blood into the straight sinuses which run to the jugu- lar foramen on each side where they meet the in- ferior petrosal sinuses, one on each side, and their junction forms the internal jugular vein. The ophthal- mic veins empty into the cavernous sinus and its blood also goes to the jugular. The anterior facial vein is formed by branches from the forehead, nose, lids, lips, and cheeks. It runs across the lower jaw with the facial artery, receives a communication from the posterior facial and empties into the internal jugular below the hyoid. The external jugular is formed by the posterior au- ricular and posterior facial. The first comes from the back of the ear; the second is formed by the union of the superficial temporal and internal maxillary and is often called temporo-facial. The vein grosses the 138 ANATOMY FOR NURSES sternor-mastoid, running downward and outward, be- neath the platysma and empties into the subclaviaii vein after crossing the third part of the subclaviaii artery. It often receives the transverse cervical and suprascapular veins. The internal jugular vein, formed by the lateral and inferior petrosal sinuses, accompanies the internal and common carotid arteries, enclosed in the same sheath, receives tributaries from the branches of the external carotid and unites with the subclavian to form an in- nominate vein. The left innominate, great transverse vein, is larger than the right lying 011 the front of the left subclavian, left carotid, and innominate arteries. The two unite at the termination of the ascending aorta to form the superior vena cava which empties into the right auricle. The vertebral veins are a plexus surrounding the ver- tebral arteries in the foramina in the transverse proc- esses. They empty into the innominate veins, which also receive the inferior thyroid and internal mammary veins. Most of the intercostal veins empty into the great azygos, a vein which begins in the abdominal cavity and passes through the posterior mediastinum to empty into the superior cava. Cardiac blood is collected by veins accompanying the coronary arteries and uniting in the coronary sinus which empties into the right auricle. THE LYMPHATICS The lymphatic system consists of numerous minute vessels ramifying throughout the body and certain small ARTERIES AND VEINS 139 glandular bodies at intervals along the vessels. They accompany the veins and are arranged in chains, notably in the groin, axilla, neck, pelvis, and abdomen. Many of them converge to form an irregular sac, the receptac- ulum chyli, on the body of the second lumbar vertebra. This contracts to a tube about the size of a wheat straw which accompanies the aorta through the posterior me- diastinum to the fourth do**aY 'vertebra where it passes behind the transverse aorta and, bending somewhat for- ward opposite the interval between the left carotid and subclavian arteries, runs into the root of the neck and, crossing the subclavian, empties into the junction of the left subclavian and internal jugular veins. Just before it terminates it receives the left duct from the left side of the head, neck and upper extremity. A smaller duct collects lymph from the right side of the head, neck and upper extremity and empties into the right subclavian. CHAPTER VII THE NERVOUS SYSTEM The nervous system consists of a large mass, en- cephalon, lying in the cranium, the spinal cord, medulla spinalis, in the spinal canal and three' sets of nerve fibers conveying impulse to and from these centers, cranial, spinal and sympathetic nerves. The central mass is enveloped in three membranes. dura mater (hard mother), pia mater (delicate mother) and arachnoid. THE DURA MATER The dura mater is a dense membrane lining the in- terior of the skull and spinal canal. Its outer surface, in the skull, corresponds to periosteum while its inner, in both situations, is lined by endothelium. The cranial dura gives off septa which separate or support subdi- visions of the brain and lodge some of the venous sinuses. The falx major is attached in front to the junction of the frontal and ethmoid bones, along the middle of the frontal, junction of the parietals and the upper half of the occipital to its anterior protuberance, where it joins the tentorium. In its upper, or attached, border is lodged the superior longitudinal sinus. Its lower border, which dips between the hemispheres of the brain, lodges the inferior longitudinal sinus. The tentorium cerebelli is attached posteriorly to 140 THE NERVOUS SYSTEM 141 the lateral limbs of the occipital cross, anteriorly to the upper border of each petrous bone, leaving a large opening opposite the basilar process for the passage of the midbrain. Along the middle of its upper surface the falx major is attached and forms the straight sinus, which receives blood from the interior of the brain. The lateral sinuses are formed in the posterior attachment of the tentorium. The upper surface of the process supports the occipital lobe of the brain while the lower covers the cerebellum. THE PIA MATER The pia mater is a thin delicate membrane binding together a network of blood vessels. It covers the en- tire brain and spinal cord, dips into the fissures found in both and enters the cavity in the interior of the cerebrum. It conducts blood vessels to and from the nerve tissues. THE ARACHNOID The arachnoid is a very delicate layer investing the pia and not separable from it in many places. It does not dip into the fissures but leaps from one elevation to another, leaving, opposite the depressions, small spaces between itself and the pia called subarachnoid spaces. THE BRAIN The brain may be divided into cerebrum, cerebellum, pons Varolii and medulla oblongata, or forebrain (pro- sencephalon), midbrain (mesencephalon) and hindbrain 142 ANATOMY FOR NURSES (rhombencephalon). The forebrain consists of the cere- brum with is commissures ; the midbrain comprises the aqueduct of Sylvius, corpora quadrigemina and crura cerebri while the hindbrain embraces the medulla, with the fourth ventricle, pons, and cerebellum. The cerebrum is much the larger part of the brain. It is composed of gray matter externally, which is the active part of the organ, and mainly of white matter internally, the conducting part, though there are masses of gray matter embedded in the white. The longitudi- nal fissure divides this mass into a right and left hemis- phere, the left, in the right-handed, being the more ac- tive. The white matter consists of fibers connecting dif- ferent parts of the same hemisphere association fibers; those running transversely and connecting the two hemispheres cornmissural fibers ; and of many fibers, as the corona radiata, which descend through the crura, pons, and medulla to connect the cerebrum with va- rious parts of the body. The exterior of each hemisphere is made up of alter- nate elevations, convolutions and depressions, fissures or sulci. Some of the latter occur at an early stage of fetal development, or in brains of a low order, and divide the hemisphere into lobes which approximately correspond to some of the cranial bones. The fissure of Rolando, or central sulcus, runs from near the middle of the hemisphere downward and for- ward for two-thirds of its vertical measurement and cuts off the frontal lobe from the parietal. The fissure of Sylvius, projecting in front of the cen- tral, and partly on the base of the brain, runs upward and backward and separates the back of the frontal THE NERVOUS SYSTEM 143 144 ANATOMY FOR NURSES and nearly all of the parietal lobes from the temporo- sphenoidal. The parieto-occipital fissure is almost entirely on the mesial surface at about its posterior fifth and separates the parietal from the occipital lobe. The precentral and postcentral sulci run in front of, and behind, the central and cut off the ascending frontal and parietal convolutions. This area is one of the best known areas in the brain. The frontal furnishes the great motor and the parietal the great sensory area of the brain. The remainder of the frontal lobe is probably, the area for thought. The occipital, on its inner surface, is marked by a wedge-shaped area, the cuneus, which is con- cerned in vision. Hearing is governed by the temporo- sphenoid lobe just below the Sylvian fissure. Taste is in the anterior part of the same lobe and smell is in a set of fibers connected with this lobe but not forming an integral part of it. The fibers at the bottom of the longitudinal fissure are called the corpus callosum, and bind the hemispheres to- gether so that their action may be coordinated. The fibers which pass in a general direction from above downward, form the corona radiata and connect the surface of the brain with the exterior of the body through the nerves. These fibers pass between two masses of gray matter embedded in the brain and form the internal capsule. This brings together the motor and sensory fibers in a very narrow space, so that a very small foreign body can compress a large number of fibers and do great damage. Under the corpus callosum there is an irregular cav- ity partly in each hemisphere and partly in the space THE NERVOUS SYSTEM 145 between them, called the ventricular cavity. This di- vides into four compartments known as the two lateral, third and fourth ventricles. The fourth is on the pons and medulla. The inferior surface of the brain corresponds to the steplike arrangement of the upper face of the base of the skull. It shows the origin of the cranial nerves and the arrangement of the blood vessels of the brain. I Corpus callosum Vision Olfactory gustatory Cerebellum Pons Medulla oblongata Fig. 18. Brain, mesial view. The crura cerebri are chiefly made of the fibers of the corona radiata which they are transmitting to the spinal cord. They appear, on the base of the brain, as tAvo round cords, as large as a finger, which converge as they pass downward and backward to the pons, into which they abruptly disappear. 146 ANATOMY FOR NURSES The pons varolii appears to consist of two rope-like bundles running from the hemispheres of the cerebel- lum and blending in a broad mass, grooved longitudi- nally, on the midline. These superficial fibers are com- missural fibers of the cerebellum and cover the longi- tudinal fibers of the crura. The cerebellum juts into the occipital fossae between the occipital lobes of the cerebrum above and the me- dulla below. The fissure separating it from the cere- brum is called the transverse fissure and lodges the ten- torium. Between it and the medulla there is a fissure Avithout name and with no process of the dura. The cerebellum consists of two lateral lobes and a middle lobe, the vermis, each having upper and lower surfaces. It is not convoluted like the cerebrum but split into thin layers by narrow sulci so that its folds are piled like tiles or shingles. The medulla oblongata is the connecting link between the brain and the spinal cord. It lies just beneath the cerebellum and tAvo bundles of its fibers can be traced directly into that body. They are known as direct cere- Cellar fibers in the cord and become the restiform bodies in the medulla from which they pass to the cerebellum, forming its inferior peduncles. Between these diverging bundles is seen the lower half of the diamond-shaped space called calamus scriptorius, which forms part of the floor of the fourth ventricle and gives origin to several cranial nerves. The upper half of the diamond is on the pons. The floor of the space is marked by a groove on the midline. The front of the medulla is also grooved longitudi- nally and presents a round eminence on either side THE NERVOUS SYSTEM 147 called the anterior pyramid. They are made up of fibers going to or coming from the crus of that side and de- scend from the medulla into the cord. The larger part of these fibers, however, cross beneath the floor of the median fissure to the opposite side of the cord, forming the crossed pyramidal tract ; and this crossing explains the fact that injury to the motor area of one hemisphere of the cerebrum causes paralysis of the opposite side. THE SPINAL CORD No line or fissure marks the point of division be- tween the medulla and cord, which corresponds to the upper two-thirds of the vertebral column. It is some- what flattened from before backward and, unlike the brain, has its gray matter in the middle. It is, appar- ently, mainly a set of conducting fibers to carry impulses to and from the brain and transmit them to the spinal nerves. It is marked by anterior and posterior fissures and, on either lateral half, by two sets of openings marking the points at which nerves emerged from the cord. Its anterior part is mainly concerned in trans- mitting motor impulses. If the cord be cut across, the gray matter in the center is seen to be arranged some- what like a capital H, whose large end is in front and whose posterior horns are longer, as well as smaller, than the anterior. The anterior give attachment to motor and the posterior to sensory nerve fibers. BLOOD VESSELS OF THE BRAIN Blood is carried to the brain by branches of the in- ternal carotid and vertebral arteries. From the carotid 148 ANATOMY FOR NURSES the anterior cerebral runs in the longitudinal fissure and supplies the mesial face of the hemisphere. The middle cerebral lies in the fissure of Sylvius and is the chief supply to the cortex of the frontal, parietal, and temporo- sphenoidal lobes. The anterior choroid enters the apex of that lobe and supplies the choroid plexus in the ven- tricular cavity. The two vertebral arteries unite to form the basilar which runs to the upper border of the pons and divides into two posterior cerebral arteries which pass to the pos- terior lobe of the cerebrum. Before the formation of the basilar, the vertebral supplies the spinal cord and its membranes and an inferior cerebellar to the cerebellum. The basilar gives anterior and superior cerebellar arteries. THE CIRCLE OF WILLIS The two anterior cerebral arteries are united by a short branch, the anterior communicating. The posterior communicating is a branch of the internal carotid which joins the posterior cerebral. These anastomoses form an irregular circle at the base of the brain. Blood starting at the right internal carotid could pass througli the anterior cerebral, anterior communicating, left an- terior cerebral, left carotid, posterior communicating and posterior cerebral into the basilar and thence for- ward through the right posterior cerebral and posterior communicating into the right carotid. From the circle of Willis branches called ganglionic arise which pierce the base of the brain and are dis- tributed to its deep substance. These arteries are called terminal because they do not anastomose in the cerebral THE NERVOUS SYSTEM 149 substance and, if one of them be destroyed or occluded, the area which it supplies dies from lack of blood; i. e., there is no collateral circulation, as on the surface of the brain or elsewhere in the body. The return circulation is cared for by cerebral veins formed on the surface and in the interior. The super- ficial empty into the longitudinal and cavernous sinuses while the deep unite to form the veins of Galen which empty into the straight sinus. THE NERVES The nerves are twelve pairs of cranial and thirty-one pairs of spinal nerves in addition to the sympathetic. The Cranial Nerves The cranial nerves are known by number from before backward and have also names more or less derived from their function. Four are appropriated to the special senses of smell, sight, hearing and taste. Three are concerned in the movements of the eye, one in sup- plying sensation to the face and motion to the lower jaw; one in supplying motion to the facial muscles, one to those of the tongue, one is almost a spinal nerve and is distributed in the neck, while the tenth scatters fibers from the head to the abdomen. Nerve fibers conduct impulses to the brain or carry orders from the brain. Sensory nerves, like those re- cognizing pain, all convey impulses from the periphery to the center, while nerves which give rise to motion, secretion, etc., carry impulses from center to periphery. The olfactory, or first, nerve recognizes odors and 150 ANATOMY FOR NURSES conveys that sensation to the brain, and no other. It can be seen at the base of the brain on either side of the longitudinal fissure in the form of an elongated mass of brain tissue which sends numerous filaments through the cribriform plate of the ethmoid to the nose. The optic, or second, nerve springs from the optic chiasum formed at the junction of the anterior and mid- dle cranial fossae by the union of two flat bands, the optic tracts, which run over the crura cerebri to pass into the midbrain and be connected with the cuneus. The middle fibers in these tracts decussate, i. e., fibers from the right hemisphere pass into the left eye; the outer pass forward in the nerve of the same side ; others, the most posterior, run in the tracts entirely and are commissural fibers between the centers, while the most anterior run from retina to retina. The whole nerve passes through the optic foramen, enters the back of the eyeball and spreads out in the retina. The motor oculi, or third, patheticus, or fourth, and abducens, or sixth, are all distributed to muscles of the orbit, the fourth entering the superior oblique, the sixth the external rectus, while the third supplies the remaining muscles of the eyeball and gives the motor filament to the ciliary ganglion which supplies the in- trinsic muscles of the eye. These nerves all lie in the outer wall of the cavernous sinus and enter the orbit through the anterior lacerated foramen. Their deep origin is from the floor of the aqueduct of Sylvius or the fourth ventricle. The trifacial, or fifth, nerve has, like a spinal nerve, two roots of which the smaller is motor. It furnishes THE NERVOUS SYSTEM 151 sensation to all the teeth, the face, front and sides of the head to the vertex, and motion to the muscles of mastication. It can be seen emerging from the side of the pons while its nucleus of origin is in the floor of the fourth ventricle. An enlargement, the ganglion of Gasser, is formed on the posterior root while lying on the petrous bone. The nerve now splits into three branches, ophthal- mic, superior maxillary and inferior maxillary. The ophthalmic division passes through the sphenoidal fissure and breaks up into a lachrymal branch to the gland of that name and the outer angle of the orbit; a frontal which, dividing into siipraorbital and supra- trochlear, named from their points of exit from the orbit, supply muscles and integument of the forehead and the upper eyelid ; and nasal which crosses the orbit, reenters the cranium and descends the nose in a groove on the nasal bone to become superficial at the lower end of that bone and be distributed to its tip. It supplies the sensory twig to the ciliary ganglion. The superior maxillary division leaves the skull through the foramen rotundum and supplies the teeth of the upper jaw, the skin over the cheek bone, sensory fibers to Meckel's ganglion and, by an infraorbital nerve, palpebral, nasal and labial branches to the lower lid, nose, and upper lip. The inferior maxillary division carries all the motor fibers. The entire nerve leaves the skull through the foramen ovale and, at the base of the skull breaks up into an anterior trunk, which contains the motor fibers for the temporal, masseter and pterygoid muscles, and a sensory twig to the buccinator, and a posterior trunk 152 ANATOMY FOR NURSES which splits into inferior dental, gustatory and auriculo- temporal. The inferior dental enters the foramen in the ramus of the lower jaw, runs in the tunnel under the teeth, supplying a branch to every fang of every tooth, and, di- viding near the mental foramen, sends one branch for- ward in the bone to supply the incisor teeth, while the larger division escapes through the mental foramen to give sensation to the lower lip. It gives off a large branch, before entering the dental foramen, to supply the mylo-hyoid and posterior belly of the digastric. The gustatory or lingual nerve runs down parallel with the lower jaw to the anterior part of the tongue where it splits into many branches for the numerous papillae of that organ. It carries with it the chorda tympani branch of the seventh whose fibers are mainly distributed to the tongue, but many pass through the submaxillary ganglion to the submaxillary and sublingual glands. The auriculo-temporal passes up over the zygoma, just in front of the ear to the skin of the temporal region. The facial or seventh nerve also has two roots. It springs from the side of the medulla, between the resti- form and olivary bodies as do the eighth, ninth, tenth, and eleventh, pursues a tortuous course through the petrous bone, emerges through the stylo-mastoid fora- men, crosses the carotid artery on a level with the lobe of the ear and breaks up into a whip-lash of branches which supply all the muscles of expression. In addi- tion it furnishes motor fibers to the stapedius, stylo- hyoid and posterior belly of the digastric and, by its cervical branch to the platysma. The chorda tympani branch joins the gustatory ancj THE NERVOUS SYSTEM 153 is the nerve of taste for the anterior two-thirds of the tongue. The facial also gives a branch to join Mack el's (the sphenopalatine) ganglion through the superficial petrosal. The auditory, or eighth, nerve emerges from the side of the medulla just below the seventh. While it seems but one nerve, it really consists of two distinct parts, a vestibular, concerned with equilibrium, which has its origin in the superior vermis of the cerebellum and its distribution in the vestibule of the ear; and a cochlear division, the nerve of hearing, connected with the cere- brum and distributed to the cochlea of the internal ear. The glosso-pharyngeal, or ninth, cranial nerve rises from the medulla just below the eighth. Its deep origin is in the floor of the fourth ventricle. The nerve leaves the skull through the jugular foramen, accompanies the internal carotid artery and jugular vein to the stylo- pharyngeus muscle when it turns in across the artery to the side of the tongue, to the posterior third of which it conveys taste. It gives off branches to the ear (tympanic), pharynx and tonsils. The pneumogastric, or tenth, or vagus, is both motor and sensory. It rises from the side of the medulla just below the ninth, goes through the jugular foramen, lies in the carotid sheath between artery and vein, passes to the neck and, on the right side, crosses the front of the subclavian artery, runs to the back of the root of the lung where it spreads out into a plexus, forms two cords to run down on the back of the esophagus to the back 154 ANATOMY FOR NURSES of the stomach, where many fibers are distributed, and finally join the celiac plexus. The left nerve enters the thorax between the carotid and subclavian arteries, behind the innominate vein, crosses the front of the transverse aorta, forms the pos- terior pulmonary plexus on the root of the left lung, passes to the front of the esophagus, where it forms a plexus with the right, and is distributed to the front of the stomach. The nerve gives motion and sensation to the pharynx, esophagus and stomach, larynx, trachea and bronchial tubes, sensation to part of the external ear and carries inhibitory and depressor fibers to the heart. The pliaryngeal branch joins a similar branch of the ninth and the sympathetic to form the pharyngeal plexus. The laryngeal branches are superior and inferior, the first sensory and the latter motor. The superior laryngeal is mainly distributed to the mu- cous membrane of the larynx, but also supplies the crico- thyroid muscle. The inferior, or recurrent, laryngeal rises on the right on the subclavian and on the left 011 the transverse aorta. In each case it curves around the corresponding vessel, runs to the interval between trachea and esopha- gus and enters the larynx at its lower back part to supply the intrinsic muscles, except the crico-thyroid. The cardiac branches arise high and low in the neck and from the recurrent laryngeal. They join the cardiac plexuses and are distributed from them. Bronchial branches, anterior and posterior, follow the bronchial tubes into the lungs. THE NERVOUS SYSTEM 155 Esophageal and gastric branches run to esophagus and stomach, respectively. The cardiac branches join the celiac or solar plexus on the side of the celiac axis. Branches of this plexus fol- low all the arteries given oft' from the axis and hence the abdominal viscera receive branches of the tenth nerve. The accessory, or eleventh, nerve is made up of a small cranial portion which appears just below the tenth at the side of the medulla, leaves the skull through the jugular foramen and joins the vagus to which it contributes the fibers which are distributed by the pharyngeal and superior laryngeal. The spinal portion arises from the spinal cord as low as the fifth cervical, enters the skull through the fora- men magnum, joins the cranial portion and leaves through the jugular foramen. It crosses the jugular vein, usually in front, pierces the sterno-mastoid high up to enter the trapezius and is distributed to those muscles. The hypo-glossal, or twelfth, springs from the side of the medulla between the olivary body and the pyra- mid. It leaves the cranium through the hypoglossal (anterior condyloid) foramen, internal to, and behind the jugular vein and internal carotid artery. It passes behind these structures and runs down to a point nearly opposite the angle of the jaw external to the artery. It now crosses the internal carotid, occipital and ex- ternal carotid arteries, rests on the hypoglossus muscle and runs into the tongue to whose intrinsic muscles it is distributed. It gives additional branches to the stylo-, hyo- and genio-glossus and genio-hyoid muscles. 156 ANATOMY FOR NURSES As the nerve crosses the carotids it gives a large de- scending branch which joins branches from the second and third cervical nerves and supplies the depressors of the hyoid, except the thyro-hyoid which gets its supply directly from the twelfth. Many of the cranial nerves communicate with each other, the sympathetic nerves and the spinal nerves, but do not form the intimate associations, called plexus, which characterize the spinal nerves. The Spinal Nerves These nerves form thirty-one pairs which have their origin in the spinal cord by two roots, emerge through the intervertebral foramina and are distributed to the various parts of the body. There are eight spinal nerves in the cervical, twelve in" the thoracic, five in the lumbar and six in the pelvic region. Each spinal nerve springs by an anterior, motor, and a posterior sensory root. The posterior roots have ganglia formed on them in the intervertebral foramina. After the union of the roots the nerves split into an- terior and posterior divisions, but these are now mixed nerves conveying both motor and sensory fibers, effer- ent and afferent, from and to the brain. The posterior divisions, generally smaller than the an- terior, pass to the muscles and integument of the back as individual nerves, not uniting to form plexus as do the anterior roots. The anterior divisions of the cervical nerves form two intercommunications called the cervical and ~brac}iial plexuses. The cervical is formed by the four upper cervical nerves and is distributed to the muscles and THE NERVOUS SYSTEM 157 skin of the neck and head. The brachial supplies the upper extremity. The thoracic nerves do not form plexuses, but pass out between the ribs, along with the intercostal arteries, to be distributed to muscles and integument in their course, the skin supply being carried by lateral cutaneous branches which rise about midway between the sternum and spine. The lateral cutaneous branch of the second intercostal joins a branch of the brachial plexus and is distributed to the upper extremity. The lower six in- tercostal nerves are often called thoracico-abdominal because they supply structures on both the thorax and abdomen. The lumbar nerves are distributed, the upper three and a half, by the lumbar plexus. The remaining nerves join the upper sacral nerves and form the sacral plexus. The spinal nerves carry fibers intended for the sym- pathetic system and these are also both afferent and efferent. They are described separately. The Cervical Plexus The cervical plexus is formed by intercommunication between the anterior divisions of the four upper cer- vical nerves. This is a very loose communication be- tween the nerves whose branches are divided into super- ficial and deep. The superficial branches are all cutaneous, that is, they convey common sensations like pain from the skin, and consist of an upper and a lower set. The upper branches have received names indicative of their distribution, small occipital (occipitalis minor), great auricular (au- 158 ANATOMY FOR NURSES ricularis magnus) and transverse or superficial cervical (superficialis colli). Together these nerves supply the broad expanse of skin from that covering the occiput to the sternum, omitting the face, the occipital taking that region; the auricular, the scalp back of the ear and over the temporal region ; and the cervical, the skin between the jaw and sternum in front of the sterno- mastoid muscle, around whose posterior border all these nerves wind. The descending superficial branches emerge from be- neath the same muscle and are divided into three sets according to their distribution, sternal, clavicular and acromial. The deep branches are muscular and communicating. The most important of the latter, from the second and third nerves, joins the descending branch of the tAvelfth cranial for distribution to the infrahyoid muscles. The muscular branches aid the eleventh in supplying the sternomastoid and trapezius. The plexus also sup- plies deep muscles of the neck. The phrenic, though a muscular branch, is important. It is the motor nerve of the diaphragm and hence the great inspiratory nerve. It is the product of the third and fourth nerves of the plexus and of the fifth from the brachial. Its course is not the same on the two sides. On the right it crosses the subclavian artery in front and behind the vein, runs outside the innominate vein and superior vena cava, in front of the root of the right lung, and descends on the pericardium to the diaphragm. The left nerve crosses the subclavian, lies external fo, and in front of, the thoracic part of that vessel, crosses the transverse aorta and runs down the THE NERVOUS SYSTEM 159 pericardium to the diaphragm. Both nerves pierce the diaphragm and are distributed to it from its under sur- face. The Brachial Plexus The plexus is formed by the four lower cervical and greater part of the first dorsal. This is a much more intimate communication than the cervical. The plexus lies between the scalene muscles, runs downward and outward to the space between the clavicle, first rib and scapula, is in close relationship to the second and third parts of the subclavian and first and second parts of the axillary artery, on the third part of which it breaks up into seven terminal branches. It is superficial just above the clavicle where only the skin, superficial fas- cia, platysma and deep fascia cover it. It is partly be- hind the second part of the subclavian, external to, and behind, the third part of that artery and the first part of the axillary and on three sides, inner, outer and posterior, of the second part of the axillary. The formation of the plexus varies, but one of the most frequent modes is that the fifth and sixth nerves unite, the seventh passes out alone ; the eighth and first dorsal form a cord. The seventh now joins the cord formed by the fifth and sixth, which gives off a large branch to unite with a similar branch from the lower cord and these form the posterior cord of the plexus. These cords do not assume their correct position until they reach the second part of the axillary artery, where they are inner, outer, and posterior cords. Branches. These are divided first into wayside and terminal, and the former into those above and below the clavicle. Above the clavicle branches are given to the supra- and infra-spinait, 160 ANATOMY FOR NURSES rhomboid, serratus, magnus, subclavius, scalene and long cervi- cal muscles. Below the clavicle the branches which supply the pectoral and subscapular muscles arise. The terminal branches supply all the remaining structures of the upper extremity. The outer and inner cords contain fibers from all the nerves of the plexus. Each gives a bra.nch to form the median nerve on the front of the third part of the axillary. The Median Nerve The median nerve passes to the middle of the front of the elbow without giving off branches, accompany- ing the axillary and brachial arteries. It supplies, di- rectly or through its interosseous branch, all the mus- cles of the front of the forearm except the flexor carpi ulnaris and the inner half of the profundus digitorum. The nerve then enters the palm and supplies the su- perficial muscles of the thenar eminence and digital branches to the front of the fingers except the little finger and inner half of the ring finger, and a branch to the skin of the palm. The Musculo-Cutaneous The remainder of the outer cord forms the musculo- cutaneous nerve which supplies the muscles of the an- terior region of the arm, gives a branch to the elbow and, becoming cutaneous, furnishes sensation to the skin of the outer half of the forearm, front and back. The inner cord carries fibers of the eighth cervical and first dorsal. In addition to giving the inner head of the median, it splits into three branches, lesser internal cutaneous, internal cutaneous and ulnar. THE NERVOUS SYSTEM 161 The Lesser Internal Cutaneous ^/St-^MHt 3>TxCki0u The lesser internal cutaneous receives the lateral cutaneous branch of the second intercostal, which some- times nearly replaces it, and is distributed to the skin covering the lower third of the postero-internal aspect of the arm. The Internal Cutaneous ^V^A.,0.1 0(^1^ &\*-Q.bi(^( The in tern a. I cutaneous takes up the supply of the skin of the forearm where the musculo-cutaneous ceases. It supplies about one-half of the forearm, commencing at the middle of the front and continuing, by the inner side, to the middle of the back. The Ulnar The ulnar nerve is the continuation of the inner cord. It is a musculo-cutaneous nerve, supplying the inner part of the elbow joint, the flexor carpi ulnaris and inner half of the flexor profundus digitorum in the forearm, all the muscles of the hypothenar group and the deep muscles of the thenar in the hand. By a dorsal branch it supplies about half the back of the hand and the palmar aspect of half the ring and all of the little fingers. The nerve passes down the arm diverging from the brachial artery, forms the " funny bone" by lying between the internal condyle and olecranon and lies to the inner side of the ulnar artery in the lower two-thirds of its course. The posterior cord has fibers from all the nerves. It is a large cord behind the third part of the axillary which is distributed to the neighborhood of the shoul- 162 ANATOMY FOR NURSES der by a branch called circumflex and to the back of the arm arid forearm by the musculo-spiral or radial. The Circumflex The circumflex is distributed to the teres minor and deltoid muscles, the shoulder, and the skin of the deltoid region. It winds around the shaft of the humerus with the posterior circumflex artery. The Musculo-Spiral The musculo-spiral, or radial, winds around the hu- merus in the musculo-spinal groove until it reaches the interval between the brachio-radialis and brachialis anticus where it gives off the posterior interosseous and continues down the forearm as the radial nerve. In the arm it furnishes sensation to the skin of the posterior and outer aspects and muscular fibers to the triceps. In the forearm it supplies, directly, or by its interosseous branch, all .the muscles on the back and outer side of the forearm. The radial continuation is a nerve of sensation only. Passing to the back of the forearm at its lower fourth, it furnishes branches to the back of the hand on the radial side and the fingers as far as the cleft between the ring and middle fingers. The Lumbar Plexus This is a loosely connected plexus behind the psoas magnus muscle formed from the first, second, third, and part of the fourth anterior lumbar divisions. Ilio-Hypogastric and Ilio-Inguinal The first branches, called ilio-hypogastric and ilio-in- guinal correspond to intercostal nerves, in that they THE NERVOUS SYSTEM 163 wind around the body in the muscular layers and sup- ply the muscles and skin on the lower part of the abdo- men, the ilio-inguinal descending to the skin of the upper inner part of the thigh and to the external genitals. The Genito-Femoral This is the nerve to the cremaster muscle of the male or round ligament of the female. It also gives a branch which supplies the skin over Scarpa's triangle. The Lateral Femoral The lateral femoral, external cutaneous, supplies the skin over the antero-external and external faces of the thigh as far as the knee. The Femoral The femoral, anterior crural, is the largest branch of the plexus being distributed from within the pelvis as far as the great toe. It is a musculo-cutaneous nerve. It passes under Poupart's ligament, external to the psoas magnus, and lies about a quarter of an inch ex- ternal to the femoral artery, where it breaks up into superficial and deep branches. The deep branches sup- ply the anterior femoral muscles, except the sartorius, while the superficial under the names middle and inter- nal cutaneous and long saphenous furnish sensation to the skin of the front and inner sides of the thigh, inner side of the leg, and inner side of the great toe. The mid- dle cutaneous also supplies the sartorius. The long saphenous is the longest nerve in the body. It accompanies the vein of the same name below the knee joint, its branches fairly corresponding to the tribu- taries of the vein. 164 ANATOMY FOR NURSES The Obturator The obturator crosses the pelvic Avail above the ob- turator vessels, leaves the pelvis through the obtrurator foramen and breaks up into many branches which sup- ply muscles of the adductor group, including the gracil- is, the hip and knee joints and the obturator externus. The Sacral Plexus The remainder of the fourth lumbar unites with the fifth to form the lumbo-sacral cord which passes over the pelvic brim to unite with the three upper and half of the fourth sacral nerves to form the sacral plexus. This plexus lies on the front of the sacrum, separated from it by the pyrif ormis muscle, with the internal iliac vessels in front of it and covered by the peritoneum and pelvic viscera. It gives branches to the external rota- tors of the thigh, a gluteal branch to the muscles of that name, an internal pudic or pudendal nerve to ac- company the artery of the same name and be distributed to the genital organs and the perineum, and terminates by dividing into a lesser sciatic nerve to the skin of the back of the thigh and the gluteus maximus muscle and a great sciatic which supplies the remainder of the lower extremity. The Great Sciatic The great sciatic, much the largest nerve in the body, leaves the pelvis, below the pyriformis, through the great sacro-sciatic foramen and runs down the middle of the back of the thigh to the popliteal space where it divides into the tibial (internal popliteal) and common peroneal (external popliteal) nerves. It supplies the hip joint and the posterior femoral muscles. THE NERVOUS SYSTEM 165 The tibial nerve accompanies the popliteal artery and vein through the popliteal space, lying superficial to both, and then the posterior tibial artery, to which it is external hxits lower two-thirds, to the ankle joint be- tween the os calcis and internal malleolus, where, like the artery, it divides into internal and external plantar nerves. It supplies three branches of the knee joint, muscu- lar branches for all the muscles on the back of the leg, a cutaneous branch to the short saphenous, formed by this and a branch of the peroneal, which supplies the skin of the back of the leg and inner side of the foot, and cutaneous branches, calcanean, to the inner side of the heel and sole. The Plantar Nerves The internal plantar, larger than the external, gives motor fibers to the muscles of the inner half of the foot and cutaneous branches to the inner three and a half toes. The external plantar gives motor twigs to the super- ficial muscles of the outer side of the foot, and to most of the deep muscles, and sensory branches to the little toe and outer side of the fourth. The Common Peroneal The common peroneal, external popliteal, nerve sup- plies two twigs to the knee joint, a cutaneous branch to aid in forming the short saphenous and divides into a deep peroneal (anterior tibial) and a superficial peroneal (musculo-cutaneous) . 166 ANATOMY FOR NURSES The deep peroneal, or anterior tibial, nerve accompa- nies the anterior tibial artery on the interosseous mem- brane, supplies the muscles of the front of the leg and dorsum of the foot and terminates in cutaneous branches to the adjoining sides of the great and second toes. It also supplies the ankle and tarsal articulations. The superficial peroneal, or musculo-cutaneous, de- scends with the peroneal muscles, which it supplies, and is distributed to the inner side of the great toe, skips the next cleft and supplies the toes from the outer side of the second to the inner side of the fourth inclusive. The cutaneous nerves, particularly in the hand and foot, communicate with each other, but by no means so frequently or so intimately as to the arteries and veins. The Sympathetic Nerves The sympathetic nerves preside over the nonstriated muscular fibers ; and, as this is very widely distributed, occurring especially in the viscera and in the vascular system throughout the body, the sympathetic nerves have an equally wide range. The essential elements of the system are a series of ganglia receiving fibers from cranial or spinal nerves, giving communications to each other and adjacent nerves, and branches of distribution to the viscera and vessels, which usually spring from plexuses formed by intercommunications between various branches of dis- tribution. Three of these ganglia, the ciliary, spheno-palatine, or Meckel 's, and the otic are connected with the divisions of the fifth nerve and constitute a large part of the ce- phalic portion of the sympathetic, the remainder of THE NERVOUS SYSTEM 167 which follows the internal carotid artery and its branches. The ciliary ganglion, supplying the nonstriated muscle of the eyeball, situated on the outer side of the optic nerve, is the most important. MecUel's lies near the spheno-palatiiie foramen and gives branches to the orbit, nose, soft palate and pharynx. The Gangliated Cord Though directly continuous with the cephalic por- tion, the spinal sympathetic is described as if it were distinct. It consists of a series of ganglia irregularly corresponding to the spinal nerves, lying in the neck, behind the carotid vessels, in the thorax on the head of the ribs, in the abdomen along the inner side of the psoas ma gnus and in the pelvis on the front of the sacrum. In the neck there are three ganglia, though the superior gives evidence of the coalescence of four, the middle and inferior of two each. In the thorax the number generally corresponds to the number of nerves, though two may coalesce. In the lumbar region there are four and in the pelvic four or five. Each ganglion consists of ascending branches which run in the cord to the ganglion above, descending to the one below, external, w r hich consist of two sets of fibers, going to and from the spinal nerves, and internal or branches of distribution. From the cervical ganglia come the branches which supply the blood vessels of the region, larynx and pharynx and the cardiac branches, which unite with branches from the pneumogastric to form the great plexus from which the heart is supplied. 168 ANATOMY FOR NURSES The thoracic ganglia supply the aorta and its branches and the lungs by branches from the upper five, while the lower seven produce the splanchnic nerves which enter the abdominal cavity and are distributed to its viscera and vessels after joining the celiac or semilunar ganglia. The celiac, or solar, plexus is a great mass of sympa- thetic fibers surrounding the origin of the celiac axis and the superior mesenteric artery. From it branches are derived which form smaller plexus on all the arte- ries in this region. We thus have gastric, hepatic, renal, and mesenteric plexus formed from which the ultimate distribution takes place. The lumbar ganglia give branches to form the aortic plexus and others which pass to the iliac vessels and form the hypogastric plexus, from which branches are given to the pelvic viscera. The pelvic ganglia give branches to the pelvic plexus and unite in the ganglion inpar on the front of the coccyx. CHAPTER VIII ORGANS OF THE SENSES The special senses are taste, smell, sight, and hearing. TASTE The organ of taste is located in the papillae on the tongue, a muscular organ consisting of bundles of muscle fibers running longitudinally, vertically and horizontally which enable it to change its shape and position, located in the space between the diverging prongs of the lower jaw and attached by its base to the hyoid bone. From the anterior two-thirds of the tongue, taste sensation is conveyed by the chorda tym- pani nerve, while the glosso-pharyngeal supplies the posterior third. SMELL The external organ of smell is the nose, a pyramidal projection, base downward, thrust forward between the eyes on either side above and the mouth below. The nose is covered by skin and divided into two cavities by a vertical median septum whose anterior third is cartilage and posterior tAvo-thirds bone, made up of the perpendicular plate of the ethmoid and the vomer. This constitutes the inner wall of each nostril, whose outer wall is composed of three shelf-like pro- jections of bone, the superior, middle, and inferior trru- 169 170 ANATOMY FOR NURSES binates, with intervening spaces which give this wall a convoluted appearance. The bones and spaces increase in length from above downward. The roof slopes up in front, runs straight back in the middle and down- ward and backward behind. The whole is covered by mucous membrane, continuous with the skin in front, the lining of the nasopharynx and eustachian tubes leading into the ear behind, the hollow, or antrum, of the upper jaw on the side and the eyes above. This membrane is particularly thick and vascular over the turbinates. The upper part of the nostrils is the olfac- tory area in which the filaments of the first nerve are distributed. The lower part of each cavity is the respiratory region. SIGHT The opening between the eyelids is called the palpe- bral fissure. The eyelids, of which the upper is the more movable, consist of two plates of cartilage, tarsal plates, covered by delicate skin and areola tissue with some pale muscu- lar fibers surrounding the fissure. Next the eyeball they are lined by a mucops membrane, the conjunctiva, which spreads from lid to eyeball and covers the tarsal glands lying between it and the cartilage. The two lids join internally and externally, but the fissure is enlarged internally and the margins of the lids show each a minute opening, puncta lachrymalia, the beginning of the lach- rymal ducts which unite in the lachrymal sac, lodged in the groove on the lachrymal bone, which contracts to form the naso-larchrymal duct conveying the tears to the nose. ORGANS OF THE SENSES 171 The lachrymal gland, which secretes the tears, is situ- ated in the hollow at the outer angle of the orbit. The ducts pour out the secretion on the conjunctiva whence it is carried into the nose. The eyelids are studded with hairs, the eyelashes, and a thicker growth of hair along the orbital ridge forms the eyebrow. THE EYE The organ of vision is a ball formed of a protecting coat, sclerotic, a vascular coat, choroid and a visual coat, retina, containing three refracting media, aqueous hu- mor, crystalline lens, and vitreous humor. The eyeball is not quite globular. Its posterior five- sixths, formed by the sclerotic, is a segment of a large sphere on the front of which is imposed a segment of a small sphere, one-sixth of the whole, formed by the cornea. The cornea and sclerotic are continuous, but the cornea is transparent and the sclerotic opaque. A line drawn through the ball from before backward is the axis of the eye whose extremities are the anterior and pos- terior poles. A line drawn at right angles to the axis through the middle and around the ball is the equator. The optic nerve pierces the sclerotic a little to the nasal side of its center and carries the central artery of the retina. It here spreads out in the retina which has a blind spot at the entrance of the artery. The point of most acute vision is a little external to this, at the fovea centralis, at the posterior termination of the axis. The sclerotic is a dense fibrous coat pierced behind by the optic nerve and, in front of that point, by numerous openings for the passage of vessels. In front it becomes 172 ANATOMY FOR NURSES continuous with the cornea, corneo-scleral junction, which it slightly overlaps, the union being marked by a slight groove. The cornea is the transparent anterior sixth of the outer tunic. It is convex in front and concave behind, its convexity varying in different individuals and at different ages, being more convex in the young. The choroid consists of three parts. The large pos- terior portion, enveloping five-sixths of the globe, is the vascular tunic of the eye. This is succeeded by the ciliary body, which continues the choroid forward, and is itself succeeded by the iris, a curtain, hanging down behind the cornea, pierced by a circular opening, the pupil. The ciliary body consists of a posterior part, continu- ous with the choroid, called the orbicularis ciliaris; from sixty to eighty infoldings of the choroid, radiating back- ward from the orbicularis, called ciliary processes ; and a circular band 3 mm. wide on the anterior part of the choroid, the ciliary, or Bowman's muscle. This consists of circular and longitudinal fibers. The latter, the more important, may be described as rising from the choroid and inserting into the ciliary processes which are fas- tened to the capsule of the lens. The iris contains circular and radiating fibers whose contractions decrease and increase the size of the pupil respectively. It hangs in front of the lens, not in con- tact with it, and divides the space between cornea and lens and capsule into anterior and posterior chambers, the anterior being limited in front by the cornea and behind by the iris and central part of the lens, the pos- terior bounded in front by the back of the iris and be- ORGANS OF THE SENSES 173 hind by that part of the lens and capsule beyond the pupillary opening. The retina is the visual coat of the eye and is essen- tially the spread out fibers of the optic nerve. Its ex- terior surface is in contact with the choroid while its interior is separated from the vitreous humor by the hyaloid membrane. Anteriorly the retina terminates, a little behind the ciliary body, in a jagged edge called the ora serrata. About 3 mm. to the outer side of the optic nerve, at the posterior pole of the eye, there is a yellow- ish oval area, macula lutea with a central depression, fovea centralis, where the retina is very thin and where vision is most acute. The refracting media are the aqueous humor, filling the anterior and posterior chambers, the lens and capsule and the vitreous humor, filling the posterior and larger segment of the globe. The aqueous humor is an alkaline fluid mainly com- posed of water. The vitreous humor is a transparent jelly-like sub- stance, albuminous in character, filling the hollow of the retina from which it is separated by the hyaloid mem- brane. The hyaloid membrane becomes thickened at the ciliary body and grooved for the reception of the ciliary proc- esses. It here splits into a very delicate layer which lies in front of a depression in the vitreous, the hyaloid fossa, for the reception of the lens, while the other is attached circumferentially to the capsule of the lens and forms its suspensory ligament. The crystalline lens lies opposite the ciliary body between the iris in front and the vitreous behind. It is 174 ANATOMY FOR NURSES circular in form, transparent, convex on both, surfaces, though more so in front than behind, and is enclosed in structureless transparent membrane called the capsule of the lens. The lens is an elastic body which hardens and loses its elasticity with age. It is kept normally slightly flattened by the pull of the suspensory ligament on the capsule. Where it is required to accommodate the eye for near vision, the ciliary muscle contracts, draws the choroid forward, relaxes the suspensory liga- ment and allows the lens to expand. When elasticity is lost with age, the muscle may continue to act, but the lens has lost its power of expansion. The iris reacts to light. When a strong light is thrown on the eye the circular fibers contract, narrow the pupil and cut off a large portion of the light. When the light becomes dim the circular fibers relax, the radiating contract, the pupil is expanded and a large amount of light is transmitted through the lens to the retina. THE EAR The organ of hearing consists of the external, middle and internal ear. The external ear, auricle, or pinna, is an irregular car- tilage, covered by skin, situated at the side of the head and prolonged into the canal in the temporal bone. The prominent rim which surrounds the greater part of the circumference is called the helix; the depression next it the scaphoid fossa; the elevation the antihelix and the deep depression in front of this and leading into the skull, the concha. The little projection overhanging the auditory canal in front is the t rag us; the one below and ORGANS OF THE SENSES 175 behind the anti-tragus; the space between the intertragic notch and the end of the ear below the lobule. There are numerous small muscles attached to the ex- ternal ear, but, in the human being, they are nearly al- ways powerless and it is a waste of time to study them. The external auditory meat us is the canal leading to the tympanic membrane which guards the middle ear. It is nearly an inch (2.5 cm.) in length, the outer third formed by the cartilage already examined and the in- ner two-thirds by bone. It is slightly curved with its general direction inward, forward and downward. It is closed by the tympanic membrane set obliquely across the canal so that the floor and anterior wall are longer than the roof and posterior. The middle ear is a small slit-like chamber at the bot- tom of the auditory canal w^hose essential features are an opening in its anterior wall by which air is conveyed to the cavity from the back of the nose through the auditory or eustachian tube; an external wall closed by the tympanic membrane ; an internal wall pierced by two openings by which this cavity communicates with the inner ear and a chain of small bones, the auditory ossicles by which the vibrations of the tympanic membrane are conveyed to the essential organ of hearing in the inner ear. Parallel with the auditory tube there is a small canal which lodges the tensor tympani muscles, whose action is to stretch the drum of the ear (tympanic mem- brane). The openings on the inner wall are the oval (fenestra ovalis) and the round (fenestra cochlea or rotunda). The oval opening is above, leads into the vestibule, and is 176 ANATOMY FOR NURSES closed by the foot of the stirrup (stapes). The round opening is below, is closed by the secondary tympanic membrane, and communicates with the cochlea. At the upper back part the tympanum is continuous with air cells in the mastoid part of the temporal bone and furnishes a space for a part of the incus. The three ossicles are the incus (anvil), malleus (ham- mer) and stapes (stirrup). The stapes is fastened by a long projection to the tympanic membrane. Its head articulates with the in- cus which is fastened by its short process in the space above the tympanum and by its long process to the stirrup. Hence if the drum is moved it moves the mal- leus, which moves the incus which, in its turn, moves the stirrup and either presses it more firmly in or draws it away from the fenestra ovalis. The vibrations of the outer membrane are thus communicated across the tympanum to the internal ear. The internal ear, or labyrinth, the point of distribu- tion of the auditory nerve, is a very minute and irregu- lar space hollowed out in the petrous portion of the temporal bone and lined by a membrane which is the exact counterpart of the space. Hence it consists of an osseous and a membranous labyrinth. This is fur- ther subdivided into the cochlea in front, the three semi- circular canals behind, and the vestibule connecting the two. The semicircular canals, which are concerned in main- taining equilibrium, are three in number. The superior an.d posterior are vertical, the superior running at right angles to the bone and the posterior parallel to its long ORGANS OF THE SENSES 177 axis. The external is horizontal. They all communicate with the vestibule. The cochlea is like a snail shell, or two and a half turns of a conical screw thrust into a circular box. The flanges of the screw (threads) would form shelf -like projections in the box, ascending to the apex of the cone, which could be prolonged to the walls by a mem- brane. The attachment of the membrane would split the space into an upper and a lower coiled tunnel each running, like a circular staircase, around a central col- umn. The central column of the cochlea is called the modiolus, is hollow and allows the nerve which lies in it to send its branches out through the threads (laminae) to reach the membrane which completes the two tunnels. The upper of these coiled chambers is called scala vesti- buli and the lower scala tympani indicating the cham- bers with which they communicate. The membrane stretching from the spiral laminaa (threads) is called the basilar membrane and supports the organ of Corti in which the terminals of the eighth nerve are found. The membranous labyrinth follows the bone exactly. The part which fills the vestibule is divided into two sacs, utricle for receiving the semicircular canals and saccule communicating with the cochlea. The membranous laby- rinth is filled with a fluid called endolymph and sepa- rated from the bony walls by another fluid, the peri- lifinph. THE LARYNX About half an inch below the hyoid bone a promi- nence can be seen on the midline of the neck which is 178 ANATOMY FOR NURSES called the Adam's apple. This is the thyroid cartilage, the largest single element of the larynx, or voice box, which is made up of cartilages, ligaments, muscles, nerves, arteries, veins and lymphatics. The chief car- tilages are the thyroid, cricoid and arytenoid (two). The Thyroid Cartilage The thyroid cartilage is a hollow wedge, base back- ward, open at both ends and behind. It is composed of two quadrilateral plates called alee, united in a blunt angle in front and expanding above and below into proc- esses called cornua. There is a deep notch in front above which gives the superior border a sinuous outline. The inferior border is shorter and thicker than the superior and its cornua are blunt and strong and marked by articular facets internally. The posterior border is rounded. The alag are marked by oblique ridges for muscular attachment. The Cricoid Cartilage The cricoid cartilage is a ring, small in front and large behind like a seal. BeloAv it is shaped like a ring of the trachea. Above it slopes rapidly upward from in front and has on either side, a quarter of an inch from the midline, an oblong articular surface for the arytenoid cartilages. On each side, near the lower border, is a circular facet for the horris of the thyroid. In the midline behind is a vertical ridge with a depres- sion for muscles on each side. The Arytenoid Cartilages The arytenoid cartilages are three sided pyramids, bases downward, facing each other on the upper back ORGANS OF THE SENSES 179 part of the cricoid. The apex of each is surmounted by small corniculate cartilages. The internal face is a plane, the posterior and external are concave. The base presents an angle directed outward and backward which gives attachment to muscles (the muscular proc- ess,) and a slender projection forward called vocal process because the vocal cords are attached to it. The Epiglottis The epiglottis is a thin leaf -like cartilage projecting upward from the larynx just at the base of the tongue. Its small end is below and is bound to the hyoid bone and thyroid cartilage by bundles of ligamentous fibers. In the natural state it appears to have its base upward, due to the folds of mucous membrane stretching out on either side. The Ligaments of the Larynx The various articular surfaces are bound together by capsular ligaments similar to those holding bones in apposition and the joints are lined by synovial mem- brane. Other bundles of fibers stretch between the cartilages and adjoining structures. A thin membrane, ihyro-hyoid, thickened at each end into a cord extends from the upper border of the thyroid to the hyoid near its upper border. A similar membrane, the crico-tkyroid, fills the gap between the lower border of the thyroid and upper border of the cricoid, which is bound to the upper ring of the trachea by a thin membrane. Stretching from the vocal process of the arytenoid to the back of the thyroid angle is a long band of elastic fibers which has no part in binding the cartilages to- 180 ANATOMY FOR NURSES gether but is intended, by its vibrations, to produce sound. It is called the thyro-arytenoid ligament or true vocal cord and is connected with the crico-thyroid mem- brane. Hyoid bone I Crico-thyroid ligament ^^_^ r M. crico-thyroid Cricoid cartilage f Trachea Fig. 19. Larynx, anterior view. The Muscles of the Larynx These are a single muscle, arytenoideus, and four pairs of muscles, crico-thyroid, posterior crico-arytenoid, lat- eral crico-arytenoid and thyro-arytenoid. The arytenoid fills the concavity on the posterior face of the arytenoid cartilages, stretching from one to the other, so that, when its fibers contract, it brings them in close apposition. ORGANS OF THE SENSES 181 The crico-thyroid is fan-shaped and attached near the front of the sides of the cricoid by one end and, by the other, to an ala of the thyroid near its lower border and inferior cornua. Its fixed point is above. It pulls the front of the cri- coid upward, makes it revolve between the inferior cor- nua, and carries its posterior portion, and the aryte- noids with it, backward, tightening the vocal cords. The posterior crico-arytenoid springs form the con- cave back of the cricoid, passes upward and outward and is inserted into the muscular process of the arytenoid. Its contraction pulls the vocal process inward, makes the arytenoid revolve on an axis through the center of its base, carrying the anterior (vocal) process outward and widening the interval between the vocal cords. The lateral crico-arytenoid rises from the upper border of the cricoid, in front of the arytenoid, passes back- ward and is inserted into the front of the vocal process. It pulls the muscular process forward, rotates the arytenoid inward and narrows the space between the cords, i. e., it is the antagonist of the posterior. The thyro-arytenoid rises from the lower part of the angle of the thyroid, runs backward and is inserted into the base and vocal process of the arytenoid. It lies paral- lel w r ith the vocal cord and is attached to it. It draws the whole arytenoid forward and relaxes the cord. The fibers inserted into the cord can relax one portion and leave the other tense. The mucous membrane Avhich leaves the back of the tongue, mounts over the front of the epiglottis, runs down its posterior face and enters the larynx which it lines. It forms glosso-epiglottic folds from the tongue 182 ANATOMY FOR NURSES * ^1 r v Rcncot^ c&TYt)a.e M .^r^cVed*- Fig. 20. Larynx, inside view. ORGANS OF THE SENSES 183 to the epiglottis; a broad fold on either side from the epiglottis to the arytenoids (aryteno-epiglottidean) ; a similar fold on either side from the thyroid to the ary- tenoid (thyro-arytenoid), the false vocal cords or ventric- ular folds and descends to cover the true vocal cords. The superior opening of the larynx slopes downward and backward; the inferior is circular and passes di- rectly to the trachea. The superior communicates with the mouth, nose, and pharynx. The space above the vocal cords is called the vestibule; that between the false and true cords and between the former and the thyroid, the ventricle and the space between the true cords the rima glottidis. CHAPTER IX HISTOLOGY Histology is microscopic anatomy. It is the study of minute cells or of tissues which have grown from cells, and of organs which are composed of tissues and cells. THE CELL The cell is the simplest form of independent life. The ovum is the name given to the primary cell from which the creature is developed. A cell is defined as a "nucleated mass of protoplasm endowed with the attributes of life." Protoplasm literally the first thing formed, is the living matter of which all animals and vegetables are formed. It makes up the mass of all cells and of it all tissues are formed. The nucleus is the somewhat centrally placed active portion of the cell. It seems to preside over cell changes and might be considered as both the brain and the generative part of the cell. The nucleolus bears to the nucleus a relation similar to that which the nucleus bears to the cell. The limiting" membrane is the thin and structureless membrane which surrounds the entire mass of proto- plasm called the cell. Intercellular cement is the substance which binds cells together. 184 HISTOLOGY 185 Growth and repair are constant phenomena of life. Growth is an increase in the number of cells or in the size of tissue. Repair is the replacement of the worn out or destroyed cells by IICAV cells. Hence it is neces- sary that cells, like higher organisms, have the power of reproduction. This process is accomplished by a di- vision of the cell into two bodies, each of which, at the end of the process, is a complete cell. Indirect division, the most common if not the only form, is that method by which the first changes occur in the nucleus and later the cell becomes constricted into a dumb-bell shape and then divides. Direct division means the constriction of the whole cell. The change in the nucleus is called mitosis or karyokinesis. When this process is completed the nu- cleus has divided into two nuclei, each in its own part of the cell and each possessed of a sort of magnetic power which enables it to draw to itself cell substance suffi- cient to form a new cell. Constriction of the body of the cell then takes place and two cells are the product of the one old cell. It is said that this process in man requires about half an hour. THE TISSUES Cells are either grouped together to form, or are dif- ferentiated into masses called, tissues. Of these we dis- tinguish epithelial, connective, muscular and nervous tissues. In addition to these formed tissues the circu- lating fluids blood and lymph, are to be considered. Numerous varieties of these primary tissues are found. The terms epi and endo thelial have been employed to distinguish those layers of cells formed on the surface 186 ANATOMY FOR NURSES or in open cavities from those formed in vessels and other closed cavities, as the serous. Eiidothelium, is, however, simply epithelium formed in these places. Epithelium, therefore, may be said to present varie- ties distinguished as endothelium and squamous and columnar epithelium. Connective tissue presents the greatest number of va- riations. Under this head are embraced white fibrous, yellow elastic, adipose (fatty), retiform (lymphoid), mucoid, cartilaginous, osseous and dentine. That is to say that tissues varying as widely as the soft fatty layer just beneath the skin and the solid bone which sustains the weight of the body, are all classed as connective tissues. Muscular tissue presents three varieties, striated, un- striated and cardiac. Nervous tissue is without such subdivisions. The Distribution of Tissues Epithelium is the most widely distributed of all tis- sues. It covers the entire surface of the body, where it is called epidermis, enters, through the mouth and nose, the digestive and respiratory tracts which it lines throughout, lines the genito-urinary tract, the ducts and acini of all glands and, as endothelium, lines the interior of all blood and lymph vessels and the great serous cavities of the body. Connective tissue, almost as widely distributed as epithelium, forms the supporting tissue beneath the skin and serous and mucous membranes, binds muscles to bones and cartilages, forms the framework of the ear (yellow elastic), of the larynx (cartilaginous), sup- HISTOLOGY 187 ports glandular organs, enters the walls of blood ves- sels and hollow viscera and, as bone, forms the frame- work of the body. Muscular tissue is formed wherever motion is re- quired. As striated muscular tissue it forms the great skeletal muscles distributed over the body ; as nonstri- ated it forms part of the walls of blood vessels, of the digestive tract, of the genito-urinary system; and as cardiac it forms the great pump which is the primary force of the circulation. Nervous tissue is found massed in the brain and spinal cord and distributed throughout the body as cranial, spinal and sympathetic nerves. The circulating fluids, Mood and lymph, are found in every portion of the body. Epithelium Epithelium is either squamous or columnar, which lat- ter may in its turn be glandular, cylindrical or ciliated. Squamous epithelium may be arranged as a. single layer of cells, when it is .called simple or pavement epi- thelium; or in many layers, when it is said to be strati- fied. A subdivision of the latter is called transitional. Endothelium is a simple epithelium consisting of a single layer of cells, united by cement along their edges, lining the closed body cavities. Openings called stomata between the cells lead to lymph vessels. Squamous epithelium consists of flat cells of varying shape, united by cement, never lining closed cavities but occurring in open cavities, as the air sacs of the lungs. Columnar epithelium consists of rod-like cells resting on a basement membrane, small end tow r ard the mem- 188 ANATOMY FOR NURSES d-a p ft ! fe J X4* O Qj ,L; ^ '-| P -d HISTOLOGY 189 brane, whose shape is irregular from the pressure of surrounding cells. Columnar epithelium lines the in- testinal canal and the glands connected with it. Goblet cells are columnar cells filled with a substance called mucin which is poured out on the mucous sur- faces where they are found. Glandular epithelium is found in the glands. The cells are of many sides from mutual pressure. Ciliated epithelium is columnar epithelium whose cells are provided with lash-like prolongations, called cilia, which produce motion independent of the move- ment of the part, and can thus extrude foreign bodies. They are especially useful in the respiratory tract and in the uterus and Fallopian tube. Stratified epithelium consists of many layers of cells which vary greatly in shape and consistency. It is found on the surface of the body where it resists pres- sure. The cells vary from nearly formless horny scales at the surface to the soft irregular forms of the deeper layers. Transitional epithelium is a modification of the strati- fied consisting of fewer layers. It is found in the bladder and ureters. The superficial layers consist of squamous cells while the deeper are elongated with small ends embedded between cells of the third layer. They look like tadpoles. Connective Tissue White fibrous tissue, connective tissue proper, con- sists of parallel bundles composed of minute fibrils, having a wavy appearance, bound together by a trans- parent cement and having connective tissue corpuscles 190 ANATOMY FOR NURSES placed at varying intervals in the bundles. When these bundles are arranged in a broad sheet of loose meshwork, leaving openings (areolae) which may con- tain some other substance, it is called areolar tissue. Such tissues are the subcutaneous, siibserous and other areolar tissues. When the areolae contain fat globules the combination of fat and fibrous tissue is called adipose tissue. When the fibrils are gathered into compact bundles with few corpuscles they form tendons, or are spread out into aponeuroses or the great investing fascias. Retiform, or lymphoid, or adenoid, tissue is a very fine connective tissue forming the framework of mucous membranes. It has many branched connective tissue cells and the cement has nearly disappeared. Yellow elastic tissue is composed of coarse branching fibers which anastomose and have a tendency to curl up. They are elastic \vhile white fibrous is not. They are found in the ligamenta subflava of the spinal col- umn and in but, few other places in the human body. CARTILAGE Cartilage is permanent when it remains unossified through life and temporary when it is replaced by bone. The latter forms the greater part of fetal skeleton. The subdivisions are hyaline, the most widely distributed, white fibro and yellow elastic. Hyaline cartilage is found chiefly on the articular sur- face of bones and in the rings of the trachea. It is sur- rounded by a fibrous vascular membrane, the perichon- drium, except in the joints. It consists of a structureless HISTOLOGY 191 Fig. 22. Human cartilage cells. Fig. 23. Hyaline cartilage. 192 ANATOMY FOR NURSES or slightly granular ground work with cells embedded and usually arranged in pairs. It has no blood vessels or nerves and derives its nourishment from the perichon- drium. Its ground substance was probably white fibrous tissue. White fibrocartilage is partly cartilage but mainly white fibrous tissue. It is found in the intervertebral disks chiefly. Yellow elastic cartilage is partly cartilage but is mainly composed of yellow elastic fibers. It is found in the ear, epiglottis, eustachian tube, etc. BONE Bone is either compact, as in the shafts of long bones, or spongy, as in the irregular bones and the extremities of long bones. All bone is modified connective tissue, the fibrils being replaced by minerals, chiefly phos- phates. The shaft of a long bone may be considered as a cen- tral large canal, or tunnel, running the length of the shaft, whose surrounding walls are composed of minute tunnels parallel with the central canal arranged in layers (lamellae) perforated by minute channels (cana- liculi) which pierce each lamella making up the sys- tem. These small tunnels or tubes are called Haversian canals. Each Haversian canal with its surrounding lamellae and canaliculi constitutes a Haversian system. At intervals the canaliculi are enlarged to form la- cunae, containing bone corpuscles. A vast number of Haversian systems, arranged like bunches of small tubes around a large central tube, go to make up a HISTOLOGY 193 long bone. The Haversian canals branch and com- municate with each other at intervals, so the blood ves- sels they contain may communicate. Between the Fig. 24. White fibrocartilage. Haversian systems, filling in the irregular intervals, are partial lamellae with canaliculi. Each Haversian canal contains an arteriole, venule, lymph channel and a nerve filament. These run through the canaliculi, piercing the lamellae in every ANATOMY FOR NURSES direction, making free anastomoses in each Haversian system; but two adjacent Haversian systems do not communicate with each other. Spongy bone has the same arrangement of lacuna? Fig. 25. Elastic cartilage. and canaliculi as compact bone, but no Haversian canals. Development of Bone. With the exception of the bones of the face and the cranial vault, bones appear in the embryo as cartilage. There follows a process HISTOLOGY 195 of enlargement of the cartilage cells and arrangement in rows. Osseous deposits take place in the matrix and processes are pushed in from the perichondrium car- rying bone cells and blood vessels. The vessels lie in / Fig. 26. Nucleated bone cells, etc. the future Haversian canals ; their branches in the cana- liculi, bone deposits are laid down between the canali- culi to constitute the future lamellae, and this process is continued until the firm bone is formed. Blood Vessels. It follows from what has been said of development that blood vessels enter compact bone 196 ANATOMY FOR NURSES from the periosteum, run in the Haversiau canals, di- vide where the canals divide, and give off numerous minute branches to the Haversian systems. The blood to the central marrow usually comes from a single large vessel which enters through a foramen in the shaft, pierces to the marrow cavity and there breaks up into Fig. 27. Transverse section of compact tissue of bone greatly magnified. ascending and descending branches. The return circu- lation comes back through the same foramen and the nerve enters it with the artery. Marrow. This substance not only fills the tubes of the long bones but extends into the cancellous tissue of their extremities and into the interstices of the ir- HISTOLOGY 197 regular bones. In the long bones it is called yellow mar- row and contains about 96 per cent fat. In cancellous bone it is called red marrow and consists of 25 per cent of all solids, a small proportion of which is fat, and 75 per cent Avater. Fig. 28. Section parallel to the surface from the shaft of the femur. Periosteum is the membrane which surrounds bone. It is made up of connective and elastic tissue, the latter forming the deep layer, contains some fat and carries the network of blood vessels and nerves which surround the bone. 198 ANATOMY FOR NURSES MUSCLE Muscle fiber is striated, nonstriated or cardiac, a va- riety resembling striated. Striated muscle fiber is the bulkiest tissue in the body, being the chief constituent of the red skeletal muscles. Nonstriated muscle fiber is found in all those organs where the contractile power of muscle is required but where its action must not be interfered with by the conscious will. The hollow intestinal canal, the uterus, bladder, blood and lymph channels are its chief seats. Cardiac muscle fiber, as its name indicates, is found only in the heart. It is striated but branched. Voluntary, or striated, muscle cut parallel to the fibers, is marked by elongated dark lines crossed at regular intervals by light transverse lines. Cross sec- tions show these bundles on end as polygonal areas called Cohnheim's fields. Each fibril consists of an elongated mass of contrac- tile substance, tapering at either end to join the next mass, contained in a delicate sheath, the sarcolemma. A number of fibrils are bound together by delicate con- nective tissue, the perimysium, forming fasciculi; while a complete muscle is formed by binding together a vast number of fasciculi by a thicker connective tissue cover- ing, called the epimysium. When muscle is united to tendon the contractile ele- ment and sarcolemma round off into a blunt point and the sarcolemma is cemented to the tendon. Blood vessels are very numerous in striated muscle. HISTOLOGY 199 Cardiac Muscle Cardiac muscle fibers are shorter and smaller than those of skeletal muscles, branch and inosculate with each other, and have no distinct sarcolemma. Nonstriated Muscle Involuntary or nonstriated muscle fibers consist of elongated or spindle-shaped cells, each containing an elongated nucleus, marked by slight longitudinal stria- tions. They are held together by a transparent ce- ment and form broad sheets arranged in various ways, i. e., running both circularly and longitudinally in the intestine, radiating in the stomach, etc., and intimately connected with the fibrous tissue of the various organs in which these muscle fibers occur. THE NERVOUS SYSTEM The nervous system consists of nerve cells, nerve fibers, connective tissue, and neuroglia and nerve ter- minals. Nerve cells, usually called ganglion cells, are of many shapes and sizes. They have large, round nuclei, with nucleoli and their protoplasm contains pigment. These cells have one or many processes springing from them and are described as nni-, hi- or multipolar. Each cell has one process called the axis cylinder process. The other processes divide and form networks. A ganglion cell with its axis cylinder process is called a neurone. Nerve fibers may be medullated, or white, or non- medullated, or gray. Each fiber consists of a central portion, the axis cylinder, an enveloping sheath, largely 200 ANATOMY FOR NURSES fatty called the white substance of Schwann or medullary sheath, and, surrounding this, an envelope of connective tissue, the neurilemma. At intervals the neurilemma is constricted so as to reach the axis cylinder. These con- strictions are called nodes of Ranvier. A collection of a number of parallel nerve fibers bound together by connective tissue called endoneurium, forms a funiculus. Many parallel funiculi, bound together by another layer of connective tissue, the perineurium, form a nerve trunk, which is surrounded by a connective tis- sue sheath called the epineurium. The epineurium car- ries the blood vessels of the nerves and dips in to blend with the perineurium. Neuroglia is a special form of very delicate connec- tive tissue, connected with the pia mater, which fur- nishes a supporting frameAVork for the brain. Large numbers of fibrils, derived from neuroglia cells inter- lace and form a network through the brain and cord. Nerve terminals are of various forms. Some sen- sory nerves lose their medullary sheaths, divide into many fibrils and have free endings between epithelial cells or in connective tissue. Others end in the tactile corpuscles of the skin, in the Pacinian bodies, in end plates in striated muscle, etc. The Central Nervous System The essential function of nerves is to conduct impul- ses between the brain and the periphery ; that of nerve cells to receive or to instigate such impulses or impres- sions. The nerve cells are, therefore, accumulated in large masses in the brain and spinal cord, Avhich is an intermediate link between brain and periphery. HISTOLOGY 201 The Spinal Cord The spinal cord is, on cross section, oval in form and partly divided by anterior, and posterior median fissures into two similar halves. The exterior is composed of me- dnllated fibers and the interior of a central gray mass arranged like an irregular capital letter H, or like two crescents with their convexities back to back, large in front, small and long behind, and held together by a transverse bar. These elongations are called the an- terior and posterior horns of the gray matter of the cord. From these horns the spinal nerves spring, the motor roots from the anterior and the sensory from the pos- terior horns. The exit of these roots through the white matter leaves a chain of minute openings which divides the cord into three columns, anterior, posterior, and lateral, the first and second bordering on the fissures of the same name and the third betAveen the other two. Further subdivision into columns is made by tracing the fibers into the medulla, the next step toward the brain. Except in arrangement of parts, the gray matter being largely on the surface, brain substance does not differ materially from that of the cord. The nerve fibers are medullated and without neurilemma in the main. There are five layers of the surface gray matter. The pia mater lies next the gray matter and sends blood vessels into the interior of the brain substance. THE BLOOD Blood contains solid bodies called corpuscles, which are either circular, biconcave disks, the red blood cor- puscles, or nearly spherical, often granular, colorless bodies called ivhite blood corpuscles or leucocytes. 202 ANATOMY FOR NURSES Bed corpuscles are about 1/3200 inch in diameter, and number about 5,000,000 to the cubic millimeter of blood. They are oxygen carriers. White corpuscles vary in size up to nearly double the diameter of the red. They vary also in number. Normally there are from five to ten thousand to the cubic millimeter of blood. White cells are capable of movement by putting out projections called pseudopodia into which the remainder of the cell may flow. They are of great importance in inflammation. Pus is largely composed of dead white cells. White cells contain nuclei and are described as leucocytes and lymphocytes. There are certain other corpuscular elements in the blood, about one-fourth the size of the red corpuscles, known as Hood plates. The coloring matter of the blood is called hemoglobin. It may be crystalized from the blood. It gives the red cells their power of carrying oxygen. THE SKIN The skin is made of two layers, the epidermis or scarf skin and the derma, corium, or true skin. The epidermis is divided into five layers of which the first and second are called the horny layer and are made up of more or less worn-out cells, like dandruff, which is derived from the first layer. The remaining three layers constitute the Malpighian layer, or rete mucosum. The cells of these three layers become more distinct in form until, in the deepest layer, they are columnar in shape and carry the pigment of colored races. * HISTOLOGY 203 The corium, derma or true skin is made up of dense fibrillated connective tissue arranged in minute eleva- tions, papillce, which indent the epidermis and carry the blood vessels and nerves of the skin. The latter often terminate in tortuous structures called tactile corpuscles. Beneath the skin there is a layer of connective tissue and fat in which the superficial bolod vessels and nerves run, called the subcutaneous connective tissue. Connected with the skin are the hairs, sebaceous and sudoriferous glands and the nails. These are called the appendages of the skin. THE CIRCULATORY SYSTEM The constituents of the circulatory system are the heart, arteries, arterioles, capillaries, venules, and veins. The heart is a hollow muscle covered on its exterior by a serous membrane, the pericardium, which is a single layer of flat endothelial cells on a fibroelastic membrane. Beneath this is a layer of connective tissue and fat, particularly along the blood vessels, similar to the subcutaneous connective tissue and fat. The connective tissue is continuous with that between the muscle fibers. Next comes the cardiac muscle fibers and then, lining the cavity of the heart, a fibro- elastic membrane supporting a single layer of flat en- dothelial cells, the endocardium. The valves of the heart are duplications of the endocardium. Blood vessels are channels conveying blood from and to the. heart. With one exception arteries carry arterial blood away from, and veins carry venous blood to, the heart. Arterioles are small arteries and venules small 204 ANATOMY FOR NURSES veins. Capillaries form the connecting link between the arterial and venous system. All blood vessels are lined with flat eiidothelial cells, cemented by their edges, continuous with the endocar- dium, and their walls are composed of nonstriated mus- cular, yellow elastic and white fibrous connective tissues, which vary in proportion with the size of the vessels. In large arteries the yellow elastic preponderates, while in arterioles the muscular fiber is in excess. Arteries consist of three coats known from within the lumen as intima, media and adventitia. The intima is mainly endothelium. The media is chiefly of muscular and yellow elastic fibers. The adventitia is nearly all white fibrous tissue with some yellow elastic. The capillaries are made up of flat eiidothelial cells held together by cement substance. In the venules the muscular and elastic elements begin to be apparent and in the veins the adventitia appears. All the coats of veins, except the intima, are thinner than the same coats in the arteries. Valves in the veins are semilunar redu- plications of the intima. Lymph channels are identical in structure with veins, but their walls are much thinner. THE SPLEEN The spleen is a ductless organ whose essential tissue, the splenic pulp, is arranged around the blood vessels. The organ is surrounded by a fibrous capsule, with a HISTOLOGY 205 layer of nonstriated muscle tissue beneath it, which sends bands, or partition walls, throughout the organ, which subdivide to form smaller compartments to con- tain the pulp. The capillaries do not unite to form venules but empty into sponge-like venous spaces, i &ff y Fig. 29. Vertical section of human spleen (modified from Kolliker), low power. t, trabeculae; m, Malpighian corpuscles; b, injected arterial twigs; s.p., spleen pulp. The clear spaces are the venous sinuses. through which the blood niters to finally enter small veins which unite to form the splenic vein. Many of the arteries are surrounded by nodules of adenoid tis- sue called Malpighian bodies. 206 ANATOMY FOR NURSES GLANDS A gland is an organ whose cells manufacture, from the blood, something to be utilized in or excreted from the body. The simplest form of gland would, therefore, be a duct or tube to convey away secretion, the paren- chyma, or cell to form the secretion, and a nerve and blood supply. > 0? J^fe. ' Fig. 30. Cross section of pancreatic tubule (modified from Sobotta). Glands may be simple tubular, coiled tubular, as in sweat glands, branched tubular, or acinous. Acinous glands consist of a single tube which becomes clubbed at its extremity and partially divided into many compartments called acini or alveoli. A number of acini, held together by delicate connective tissue, form a lobule; several lobules may be bound up in the same way to form a lobe, and all the lobes, enveloped in a HISTOLOGY 207 capsule of connective tissue, form a compound acinous gland. This arrangement gives rise to a many-branched duct to convey the secretion from the gland. All the branches from one lobule unite to form an intralobular duct, which unites with the ducts of adjacent lobules to form an interlobular. duct, running between the lobules ; and these, in turn, unite to form the main duct of the gland, as in the duct of Wirsung of the pancreas or Stensoii's duct of the parotid. The salivary, buccal and mammary glands and the pancreas are all compound racemose or acinous glands. Slight differences in structure are found in the sub- lingual, a mucous gland, and the submaxillary, a mixed gland, which differentiate them from the pure serous glands like the parotid; but the general type is the same. In all the blood vessels and nerves, with which they are abundantly supplied, follow the branches of the duct until it enlarges into alveoli which are sur- rounded by the vessels, bringing their contents into closest contact with the active cells of the glands. The dividing and supporting bands of connective tissue are all derived from the capsule or envelope. The Liver The liver, the largest of the glandular organs, is sur- rounded by a dense connective tissue envelope, the capsule of Glisson, covered by peritoneum, which sends branching septa throughout the organ subdividing it into numberless minute subdivisions called lobules. Every lobule is made up of liver cells, the parenchyma, and connected with four channels or vessels, two of which convey something to and two something from the lobule. 208 ANATOMY FOR NURSES b.d. h.a. Fig. 31. Portion of transverse section of human liver. X. 100 h.a., hepatic artery; v.c., intralobular vein; v.p., interlobular vein; b.d., bile duct. HISTOLOGY 209 The whole object is to put the liver cells in intimate as- sociation with the blood and bile vessels. Hence the structure of the liver can be understood only when the arrangement of these vessels is comprehended. The vessels run in the bands of connective tissue which at once support the lobules and separate them from each other. The hepatic artery and the portal vein carry blood into the liver. The hepatic veins and the bile duct carry blood and bile respectively from the liver. The artery, portal vein, and bile duct enter the liver through the transverse fissure and at once begin to divide into small and smaller branches until, finally, a very minute branch of each is found in the connective tissues which surround each lobule. From these small- est vessels capillaries are given off. which penetrate the lobules between the liver cells. The cell are now in con- tact with (a) arterial capillaries carrying blood to nour- ish the liver; (b) portal capillaries carrying blood to be acted on by liver cells; (c) bile duct capillaries to pick up the secretion of the liver cells; and (d) hepatic capil- laries to take up the bile free blood and convey it to the center of the lobule where these capillaries empty into, or form an intralobular venule which is the beginning of the hepatic veins. The direction of the current in the portal and arterial capillaries is toward the lobule, in the hepatic and bile capillaries, away from the lobule. The portal, arterial and bile vessels lie between the lobules and are interlobular. The interlobular veins unite beyond the lobules into veins called sublobular. Within the lobules, packed between the capillaries, lie the liver cells. 210 ANATOMY FOR NURSES THE DIGESTIVE TRACT The canal beginning at the mouth and ending at the anus is subdivided into mouth, pharynx, esophagus, stomach, small and large intestines. The Mouth, Pharynx, and Esophagus The mouth is lined by a mucous membrane which con- sists of stratified epithelium. The tongue, which consists chiefly of striated muscle, is marked on its upper surface by a large number of pa- pillae which are distinguished from each other by being filiform or conical in shape, fungiform, having a con- stricted base, or circumvallate, which are fungiform in shape but surrounded by a depression with a wall-like elevation. They are located at the back of the tongue Taste buds are flask-shaped collections of epithelial cells around the circumvallate papillae and at other places on the tongue. The teeth are calcareous structures, divided into an exposed part called the crown, a constricted portion, the neck and a root or roots embedded in the alveolus or socket of the jaw. The crown is covered by the hardest structure in the body, the enamel. Beneath this is a layer derived from connective tissue called dentine, not so hard as enamel, pierced by radiating canals in which vessels and nerves lie, surrounding a pulp chamber which con- tains the main vessels, nerves and lymphatics of the tooth, bound together by connective tissue and forming the pulp. The tonsils are large collections of lymphoid tissue containing many lymph follicles. The surface and HISTOLOGY 211 crypts of the tonsils are covered by stratified squamous epithelium. The pharynx above the soft palate is covered by ciliated columnar epithelium; below the palate, by stratified squamous epithelium. The esophagus is lined by stratified" squamous epithelium resting on connective tissue, the two form- ing the mucous coat. External to this are the mus- cularis mucosa, submucosa and muscular coats which are striated in the upper third and unstriated in the remainder. The Stomach and Intestines The stomach and intestines are made up of a mucous coat, which consists of epithelial lining, mucosa and muscularis mucosa which is a very thin layer of non- striated muscular fibers separating the mucous mem- brane and the submucosa. The latter is a layer of loose areolar tissue, corresponding to subcutaneous connective tissue, which connects the muscular and mucous coats and carries the larger vessels, nerves, and lymphatics. The muscular coat is made up of an inner circular and an outer longitudinal layer of nonstriated muscle. External to this is a subserous layer of connective tissue and then the partial or complete peritoneal or serous coat. The mucous coat may be thrown into folds called rugae in the stomach and valvulce conniventes in the small intestines, which greatly increase the extent of its surface. The mucosa of the stomach is marked by minute de- 212 ANATOMY FOR NURSES pressions, gastric tubules or glands, which produce the gastric juice. Those in the cardiac end are called peptic glands; while the pyloric are situated in the small end of the organ. The intestines are formed on the above plan, the Fig. 32. 'Injected lacteal vessels in two villi of human intestine. (Teich- mann.) X 100. L,acteals filled with white substance and blood vessels with dark. longitudinal muscular coat of the large being gathered into three bundles instead of forming a thin layer around the circumference of the canal. The mucosa, of the small intestine is studded by in- numerable elevations, villi, separated by depressions of similar minuteness, the crypts of Lieberkiihn, which HISTOLOGY 213 correspond to the tubules of the stomach. Every villus has passing into it an arterial capillary and from it a venous capillary and a lacteal. The first carries blood to nourish the villus, the second carries the return circulation containing the usual waste products plus the products of digestion, while the third conveys certain blood products, chiefly fat, into the lymph spaces and channels in the submucosa and thence into the larger lymphatics of the mesentery. The cells lining the villi secrete a part of the intestinal fluid succus entericus while the remainder is formed by glands of Brunner located below the crypts of Lieber- kiihn and opening into the crypts. Connected with the lymphatic plexus in the submu- cosa are lymph nodules improperly called glands. These are sponge-like bodies through which the lymph filters, its circulation being always in the direction of the venous blood. THE KIDNEY The kidney is surrounded by a fibrous capsule w r hich sends delicate septa throughout the organ. Its blood vessels, nerves, and duct enter or leave at the hilum. As its function is to extract the urinary solids, and water to hold them in solution, from the blood, its es- sential structure is that of a set of capillaries so ar- ranged that they will be surrounded by kidney cells, set in tubes, which can remove the urine from the blood and pour it into the tube. If the kidney be split along its outer border, it will be seen to consist of a dark outer and a lighter inner portion, distinguished 214 ANATOMY FOB NURSES Fig. 33. Diagrammatic representation of the course of the uriniferous tubules and the kidney vessels. HISTOLOGY 215 as cortical and medullary. In the cortical (outer) por- tion the work of removing urine from the blood is in the main performed, while the medullary part is largely occupied by minute tubules conveying the urine to the excretory duct ureter. If the small arterioles be traced to the cortex they will be found to terminate in a curious tuft of capil- laries called Malpigkian bodies or glomeruli; and each tuft is surrounded by the expanded end of a tubule, Bowman's capsule, whose lining of flat epithelial cells is reflected over the glomerulus. The small tubule lead- ing from Bowman's capsule, after winding about as the first convoluted tubule, runs a short distance into the medullary portion and then turns upward and re- enters the cortical area, the U-like loop thus formed being known as Henle's loop, while the tortuous part which reenters the cortex is the second convoluted tu- bule. After the formation of the glomeruli from an afferent arteriole, these capillaries contract to form an efferent arteriole which penetrates Bowman's papsule and breaks up into a second series of capillaries in the region of the convoluted tubules. From these last the venous capillaries are formed and remove the urine- free blood from the kidneys. The blood has been brought in contact with the kidney cells at two points, i. e., in Bowman's capsule around the Malpighian tufts and in the convoluted tubules by the second series of capillaries. The second convoluted tubule now runs a nearly direct course into the pyramids from which the urine drops into a calyx, the beginning of the ure- ter. Several calices unite to form an infundibulum 216 ANATOMY FOR NURSES and the three infundibula unite to form the pelvis of the ureter which contracts to the ureter proper. ORGANS OF RESPIRATION The organs of respiration are the larynx, trachea, bronchi, and lungs. The function of these organs is to effect an exchange of gases in the blood and to produce articulate sound. The larynx, trachea, and bronchi have a framework of hyaline cartilage, except the epiglottis which is yellow elastic, and each is lined by epithelium which is strati- fied squamous over the epiglottis and upper third of the larynx and stratified columnar and ciliated else- where. Next to the epithelium lies the mucosa or in- ternal fibrous coat, containing collections of lymphoid tissue and nutrient vessels. Next to this lies the mus- cidaris mucosa followed by the external or submucous coat containing the mucous glands and external to this is the cartilage, where it exists. The two bronchi divide, the right into three and the left into two branches for the corresponding lobes of the lungs. Each of these primary bronchi again di- vides and these smaller tubes again divide, the process being repeated until the terminal bronchioles are reached. As this division proceeds the cartilage is lost, then the mucous coat and its glands disappear and lastly the muscular coat ceases, the cilia disappear, and the epithelium becomes cuboidal in form. Each bron- chiole has now apparently dilated into a wide space termed an infundibulum whose walls are hollowed out into a number of air cells or alveoli lined by a single HISTOLOGY 217 n ^T*~, Fig. 34. Diagram of the ending of a bronchial tube. layer of flat pavement epithelium supported on a fibro- elastic tissue framework carrying a large number of capillaries. The bronchial arteries, which carry nutrient blood to the lungs, with the bronchial veins for the return circu- lation, follow the bronchi. Entering each lung, near the 218 ANATOMY FOR NURSES middle of its inner surface, is a pulmonary artery. This artery carries venous blood. Its subdivisions follow the bronchioles until its capillaries form a rich network around every alveolus and the C0 2 in the blood is thus brought into intimate relationship with the in the air cells. The capillaries of the pulmonary veins take up the blood after C0 2 has been exchanged for and unite to form radicles which unite to form the veins which in turn form the pulmonary veins which convey the oxygen- charged blood to the left side of the heart. The union of many primary air sacs forms a lobule and the lobules are combined until a lobe of the lung is formed. Each lung is lined on its exterior by a serous mem- brane, the pleura, covered on its superficial surface by endothelium resting on a fibroelastic layer which sends septa into the lungs to divide them into lobes and ulti- matelv into lobules. INDEX Alxlomeii, 91 Abdomina] aorta, 114 viscera, 91 Acromion process, 32 Alimentary canal, 90 Ankle joint, 61 Anterior fossa of skull, 51 region, skull, 47 Antrum Highmore, 47 Anus, 96 Aorta, 112 abdominal, 114 ascending, 112 thoracic, 113 transverse, 113 Appendix, vermiform, 94 Aqueous humor, 173 Arachnoid membrane, 141 Arm, arteries, 126 muscles, 80 nerves, 160 veins, 135 Artery, or arteries, 107 axillary, 125 basilar, 148 brachial, 126 calcanean, 133 carotid, external, 121 internal, 123 left, 120 right, 120 circumflex, 126 colica dextra, 117 media, 117 sinistra, 117 coronary, 112 digital, 128 facial, 121 femoral, 131 gastric, 115 gluteal, 130 hepatic, 115 Artery, or arteries ContM iliac, common, 129 external, 130 internal, 129 innominate, 119 internal mammary, 125 maxillary, 122 * plantar, 133 lingual, 121 ophthalmic, 123 phrenic, 144 plantar, 133 popliteal, 132 pulmonary, 109 radial, 127 renal, 118 subclavian, 124 temporal, 122 thyroid axis, 124 tibial, anterior, 132 posterior, 133 ulnar, 128 vertebral, 124 Articulation, ankle, 61 carpal, 64 costo-vertebral, 56 elbow, 59 hip, 57 jaw, 63 knee, 60 pelvis, 64 shoulder, 57 vertebral, 54 wrist, 62 Articulations, general, 52 Ascending colon, 94 Astragalus, 43 Atlas, 26 Auditory nerve, 153 Axilla, 126 Axillary artery, 125 vein, 136 Axis, 26 219 220 INDEX B Base of brain, 145 skull, 51 Basilic vein, 136 Bladder, 98 Bone, or bones, astragalus, 43 atlas, 26 axis, 26 calcaneum, 42 carpal, 41 clavicle, 30 coccyx, 27 cranial, 45 cuboid, 43 femur, 36 fibula, 40 frontal, 47 humerus, 35 hyoid, 45 ilium, 32 inferior maxillary, 50 turbinate, 50 innominate, 32 ischium, 32 nasal, 47 occipital, 45 patella, 39 radius, 37 rib, 27 sacrum, 27 scaphoid, 44 scapula, 31 sternum, 27 tarsal, 42 tibia, 39 ulna, 38 Brain, 141 base of, 145 convolutions, 142 membranes, 140 Bronchi, 105 C Capsular ligaments, 55 Celiac axis, 115 Cerebellum, 146 Cerebrum, 142 Clavicle, 30 Cranial bones, 45 nerves, eighth, 153 eleventh, 155 Cranial nerves Cont'd fifth, 150 first, 149 fourth, 150 ninth, 153 second, 150 seventh, 152 sixth, 150 tenth, 153 third, 150 twelfth, 155 Crystalline lens, 173 D Duodenum, 93 E Ear, 174 Elbow joint, 59 Epiglottis, 179 Esophagus, 91 Eye, 171 F Face, arteries of, 121 bones, 47 muscles, 75 Fauces, 90 Female generative organs, 99 Femoral artery, 131 Fifth nerve, 150 First nerve, 149 Foot, arteries of, 137 bones, 43 muscles, 89 nerves, 165 Fossa of skull, 51 G Gangliated cord, 167 H Hand, arteries, 128 bones, 41 muscles, 83 Heart, 102 Hip joint, 57 Humerus, 35 I Ileum, 94 Iliac arteries, 129 INDEX 221 Ilium, 32 Inferior vena cava, 135 Intestines, large, 94 small, 94 Ischium, 32 K Kidney, 98 structure of, 213 Knee joint, 60 Larynx, cartilages, 177 ligaments, 179 muscles, 180 Ligaments, 52 ankle, 61 elbow, 59 hip, 57 jaw, 63 knee, 60 pelvis, 64 shoulder, 57 wrist, 62 Liver, 96 structure of, 207 Lungs, 105 structure of, 217 Lymphatics, 138 M Manubrium, 27 Mediastinum, 105 Medulla oblongata, 146 Membranes of brain, 140 of cord, 147 Mouth, 90 Muscle, or muscles, 67 adductor group, 85 arytenoid, 180 biceps, arm, 81 thigh, 85 bronchialis anticus, 81 constrictors of pharynx, 91 coraco-brachialis, 81 crico-arytenoid, 181 crico-thyoid, 181 deltoid/ 80 diaphragm, 71 digastric, 74 erector spinal, 79 Muscle, or muscles Cont 'd extensors, forearm, 82 leg, 88 flexors, 81 of abdomen, 68 of arm, 79 of back, 77 of eyeball, 75 of face, 75 of forearm, 81 of foot, 89 of hand, 83 of hip, 84 of leg, 87 of neck, 73 of thigh, 85 pectoral, 72 psoas, 85 pterygoid, 75 N Xeck, arteries, 120 muscles, 73 veins, 137 Nerve, or nerves, 149 auditory, 153 brachial plexus, 159 cervical plexus, 157 chorda tympani, 152 ciliary, 167 circumflex, 162 dental, 157 dorsal, 157 eighth pair, 153 eleventh pair, 155 facial, 152 fifth, 150 fourth, 150 frontal, 151 glosso-pharyngeal, 153 great sciatic, 164 gustatory, 152 hypoglossal, 155 intercostal, 157 laryngeal, recurrent, 154 lumbar plexus, 162 median, 160 musculo-spiral, 162 ninth, 153 olfactory, 149 ophthalmic, 151 optic, 150 222 INDEX Nerve, or nerves Cont'd Shoulder joint, 57 phrenic, 158 Skull, 45 plantar, 165 Spinal cord, 147 pneumogastric, 153 histology, 201 popliteal, or peroneal, 165 nerves, 156 radial, 162 Spine, 22 sacral, plexus, 164 Spleen, 97 saphenous, 163 structure, 204 sciatic, 164 Sternum, 27 seventh, 152 Stomach, 93 sixth, 150 structure, 211 sympathetic, 166 Subclavian artery, left, 120 tenth, 153 right, 124 third, 150 Sympathetic nerves, 166 thoracic, 157 tibial, 166 T twelfth, 155 Testes, 101 ulnar, 161 Thorax, 27 vagus, 153 Thyroid cartilage, 178 Trachea, 105 O U Obturator artery, 130 Ulna, 38 muscles, 84 Ulnar artery, 128 nerves, 164 nerve, 161 . Os calcis, 42 Ureter, 98 / p Urethra, female, 98 male, 98 Palmar arteries, 128 Uterus, 99 muscles, 83 Pancreas, 97 V structure of, 207 Vagina, 100 Patella, 39 Vein, or veins, 134 Pelvis, 33 axillary, 136 ligaments of, 64 basillic, 126 viscera of, 99 cava, inferior, 135 Pharynx, 91 superior, 138 Pleura, 104 cephalic, 136 R femoral, 135 iliac 135 Radial artery, 127 innominate, 138 nerve, 162 Radius, 37 Rectum, 96 Renal artery 118 Retina, 173 jugular, 137 popliteal, 135 portal, 118 saphenous, 134 subclavian, 137 Ribs, 27 Vertebral, 23 Vertebral column, 22 Sacral plexus, 164 Viscera, 91 Sacrum, 28 Vocal cords, 180 Scapula, 31 Sciatic artery, 130 nerve, 164 Willis, circle of, 148 UNIVERSITY OF CALIFORNIA MEDICAL SCHOOL LIBRARY THIS BOOK IS DUE ON THE LAST DATE STAMPED BELOW I SEP I M "K i 8 1924 JUN 2 1924 AUG 4 1924 OCT 22 DHL N'OV 1 - 1928 DEC 1 7 1330 V 23 I! EEfi <; 1 1942 OECl- 1943 ll 5944 1 7 1 4 194S lm-11,'18 University of California Medical School Library