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THE ANATOMY 
 OF THE PEEITOI^^UM 
 
THE 
 
 ANATOMY OF THE 
 PERITONEUM 
 
 1 
 
 BY 
 
 FRANKLIN PEXTER, M. D. 
 
 ASSISTANT DEMONSTRATOR OF ANATOMY, COLLEGE OF PHYSICLAJfS 
 AND SURGEONS (COLUMBIA UNIVERSITY) NEW YORK 
 
 WITH THIRTY-EIGHT ILLUSTRATIONS 
 
 NEW YORK 
 D. APPLETON AND COMPANY 
 1892 
 
Copyright, 1892, 
 
 bt d. appleton and company. 
 
QMS&7 
 
 PREFACE. 
 
 From my experience in the dissecting-room, there 
 seems to me to be no part of anatomy which is quite 
 so unsatisfactory or incomprehensible to the student 
 as the peritonaeum. It is impossible to offer an expla- 
 nation of why anatomical conditions present them- 
 selves as we find them, but in some cases, at least, we 
 can explain how such conditions are produced, and 
 if one understands this his knowledge is of a more 
 satisfactory kind, and does not degenerate to a mere 
 matter of memory. Moreover, if one follows the de- 
 velopment of the organs, and is able to understand 
 the changes produced in the abdominal cavity by this, 
 he not only gains valuable information as to their 
 normal position, but can more easily understand the 
 abnormities that occur. There is no way of obtain- 
 ing a clear idea of the peritonaeum except through 
 a knowledge of its development. It is this belief 
 which suggested to me the writing of this pamj^hlet. 
 The matter contained in it is not original in any sense 
 of the word. 
 
6 ANATOMY OF THE PERITONEUM. 
 
 I believe it was Prof. Toldt, of Vienna, who first 
 gave tbe true description of the development of the 
 peritonseum. His article was, of course, written in 
 German, and therefore is useless to most of our stu- 
 dents. It seemed to me that if one should take his 
 description as a basis, make many more plates than he 
 gives in his work, and so take the student along, step 
 by step, in the most elementary way, he would not only 
 be able to follow the description with comparative 
 ease, but in the end would have an understanding of 
 the subject. It is with this idea that this pamphlet is 
 offered to students of anatomy. To those further ad- 
 vanced in the science, the sketches will seem far too 
 diagrammatic to coincide with accuracy — and I agree 
 with them — but I have tried to keep the main object 
 in view, namely, that it is not the embryological de- 
 tails which the student is trying to learn, but their 
 result. For this reason it has been made most dia- 
 grammatical, with the hope that he will more easily 
 be enabled to follow each step in the development. 
 There is much in regard to the development of the 
 liver and diaphragm which is not understood, and 
 therefore the simplest possible explanation has been 
 chosen. Even though in some details it be incor- 
 rect, it may aid the student in obtaining an idea 
 of the peritoneal connections between the organs. 
 Should this pamphlet give the required aid, its object 
 will have been accomplished. 
 
PKEFACE. 7 
 
 I would here express my sincere thanks to Prof. 
 C. S. Minot, of Harvard University, as well as to 
 Prof. George S. Huntington, of the College of Physi- 
 cians and Surgeons, Colunibia University, for the aid 
 and many valuable suggestions which they have given 
 me ; as well as acknowledge my indebtedness to my 
 former teacher. Dr. F. Hochstetter, assistant at the 
 Vienna University, for the many hours which we 
 have passed together in the study of this subject. I 
 am also indebted to Toldt, Hertwig, Gegenbauer, 
 Quain, and Gray, for sketches taken from their 
 works. 
 
 Franklin Dextee, 
 Assistant Demonstrator of Anatomy, 
 College of Physicians and Surgeons, 
 
 New York. 
 
ANATOMY OF THE PERITONAEUM. 
 
 DEVELOPMENT OF THE ALIMENTARY 
 CANAL. 
 
 Fig. L 
 
 Median section of an embryo. In a very young 
 embryo the alimentary canal resembles a tube in its 
 form. 
 
 Fig. II. 
 
 At a later date a slight enlargement occurs in it, 
 which is the first indication of the stomach, and infe- 
 riorly the canal makes a distinct bend. 
 
Fig. I. — A, Aorta. 
 Ac, Alimentary canal. 
 
 Fig. II. — S, Rudimentary 
 stomach. A, Aorta. B, 
 Bend in intestine. 
 
10 ANATOMY OF THE PERITONAEUM. 
 
 Fig. III. 
 
 The enlargement (stomach) increases in size, the 
 bend in the intestine grows more pronounced, and the 
 lowest loop of the bend is approximated to the upper 
 part of the intestine. 
 
Fig. in. — S, Stomach. A, Aorta. B, Bend in intes- 
 tine. 
 
12 ANATOMY OF THE PERITONEUM. 
 
 Fig. IY. 
 
 At about this time a differentiation in the size of 
 the intestine takes j)]ace. The bend in the large has 
 crossed the small intestine, and just below the stom- 
 ach two sprout-like processes are given off from the 
 small intestine, one anteriorly and one posteriorly to 
 it. These are the first indications of the liver and 
 pancreas respectively. 
 
Fig. ly. — S, Stomach. A, Aorta. C, Colon. L, Liver. 
 P, Pancreas. 
 
14 ANATOMY OF THE PERITONEUM. 
 
 Fig. y. 
 
 An anterior view of an embryo in the next stage 
 of development shows us that tlie large intestine has, 
 so to speak, fallen over the small intestine. This 
 happens in such a manner that the large intestine 
 comes to lie anteriorly to the small, crosses it, and 
 indicates in a general way the direction of the trans- 
 verse and descending colon. The liver and pancreas 
 have not here been drawn in, for the sake of sim- 
 plicity. 
 
-— \— Tc 
 
 Coe— 
 
 ■--De 
 
 Fig. V. — A, Aorta. S, Stomach. Tc, Transverse colon. 
 Dc, Descending colon. Coe, caecum. 
 
10 ANATOMY OF THE PERITONEUM. 
 
 Fig. YI. 
 
 At a later date the differentiation in the size of 
 the intestines is more marked. The vermiform ap- 
 pendix is not of uniform size, as in the adult, but it 
 seems to be, as it really is, a portion of the caecum. 
 That there is no ascending colon is an important 
 point, as well as the high position of the caecum. 
 Later, the first portion of the large intestine grows 
 downward, until the caecum reaches its normal po- 
 sition in the right iliac fossa. In this way the as- 
 cending colon is formed. That the caecum has nor- 
 mally this high position in the embryo is important, 
 for I have seen cases in the dissecting room of chil- 
 dren whose caeca were found to be in relation to the 
 liver rather than to the iliac fossa. This abnormity 
 can easily be accounted for by the lack of develop- 
 ment of the ascending colon. 
 
Fig. VI. — Coe, Caecum. Va, Vermiform appendix. 
 A Aorta. 
 
18 ANATOMY OF THE PERITONEUM. 
 
 Fig. YII. 
 
 The stomach has now more its adult form — that is 
 to say, its two ends have approached each other, and, 
 moreover, it is so turned tliat what was formerly its 
 anterior border is now its superior or lesser curvature, 
 and what was its posterior border is now its inferior 
 or greater curvature. This is important, as we shall 
 see later. The small intestine has greatly increased 
 in length, and the caecum has reached its normal 
 position, in the right iliac fossa. 
 
Fig. VII. — S, Stomach. Ac, Ascending colon. Tc, 
 Transverse colon. Dc, Descending colon. Coe, 
 caecum. 
 
20 ANATOMY OF THE PERITONAEUM. 
 
 MESENTEEY 
 
 Fig. YIII. 
 
 The blood-vessels supplying the alimentary tract 
 need some support, and they find it in a more or less 
 loose connective tissue which binds them together. 
 It is necessary that they should have a lubricated sur- 
 face, in order to diminish friction, and so allow the 
 peristaltic movement of the intestines to be carried on 
 as smoothly as possible. So the blood-vessels in their 
 bed of connective tissue are surrounded by a shining 
 membrane called the peritonseum. All these together 
 — vessels, tissue, and peritonaeum — constitute what is 
 known as the mesentery. 
 
 Every organ has its mesentery, under that name 
 or some other. For instance, the name mesentery is 
 usually applied to the mesentery of the small intes- 
 tine ; the mesocaecum, to the mesentery of the cae- 
 cum ; the transverse mesocolon, to the mesentery of 
 the transverse colon ; and the mesorectum, to the 
 mesentery of the rectum. Moreover, other organs 
 have their mesenteries, though their nature is not 
 designated by their name. The lesser omentum is 
 the mesentery of the liver, the greater omentum the 
 mesentery of the stomach, spleen, and pancreas. It 
 will be seen from this that mesenteries vary much in 
 thickness. They may be very thin, like the omenta, 
 or much stronger, as in the ascending mesocolon. 
 
Fig. VIII. — Vp, Visceral peritonaeum. Pp, Parietal 
 peritonaeum. M, Mesentery. I, Intestine. T, Con- 
 nective tissue. V, Vessels. 
 
22 ANATOMY OF THE PERITONEUM. 
 
 Fig. IX. 
 
 Figs. IX, X, and XI are transverse sections of 
 an embryo at different ages, to show two points: 
 first, that the peritonaeum is developed simultaneous- 
 ly with the intestine ; second, to show the mode of 
 development of the mesentery. 
 
 Fig. IX is the youngest embryo, and at this date 
 the intestine is not closed ; nevertheless, it is entirely 
 covered by peritonaeum (the green line), which is re- 
 flected on to the sides of the peritoneal cavity. This 
 shows us that there are two forms of peritonaeum — 
 one usually described as the visceral, because it sur- 
 rounds a viscus ; the other as the parietal, because it 
 lines the parietal walls. The peritonaeum of the me- 
 sentery is always of the former variety. In these 
 drawings the parietal peritonaeum will be represented 
 by a green line ; but all mesenteries — ^to show that they 
 are such — by a black line between two green ones. 
 The black line corresponds to the connective-tissue 
 support of the vessels. We see, then, that the peri- 
 tonaeum is developed simultaneously with the intes- 
 tine, and that the intestine has not, after it has been 
 formed, been pushed into the membrane as a finger is 
 into a glove. This explanation or comparison of the 
 covering of the intestine by peritoneum, which is so 
 often given, is not a fortunate one, for it implies at 
 least a totally wrong principle. 
 
Fig. IX. — Pp, Parietal peritonaeum. . Vp, Visceral peri- 
 tonaeum. I, Intestine. Pc, Peritoneal cavity. 
 
24 ANATOMY OF THE PERITONEUM. 
 
 Fig. X. 
 
 Fig. X represents the embryo at a later date. 
 The intestine is gradually closing, and is attached to 
 the embryo by a very short mesentery. 
 
 Fig. XL 
 
 In Fig. XI the shape of the embryo is somewhat 
 changed. The intestine is closed, and the mesentery 
 has very much increased in length. It increases in 
 length by growth, which might be likened to a pro- 
 cess of stretching. 
 
Fig. X. — M, Mesentery. 
 
 Fig. XL — Pc, Peritoneal cavity. Pp, Parietal perito- 
 naeum. Vp, Visceral peritonaeum. M, Mesentery. 
 I, Intestine. 
 
26 ANATOMY OF THE PERITONEUM. 
 
 Fig. XII. 
 
 For the sake of simplicity, when considering the 
 development of the alimentary canal, its mesenteries 
 were omitted. On the examination of a very young 
 embryo at a period when its alimentary canal presents 
 a tube-like appearance, we find that it possesses two 
 mesenteries — a posterior mesentery, attached anteri- 
 orly to the alimentary canal and posteriorly to the 
 aorta. Its vessels (not here represented) are branches 
 of the aorta. It has also an anterior mesentery, at- 
 tached posteriorly to the canal and anteriorly to the 
 median line of the abdominal wall. This mesentery 
 extends only as far downward as the umbilicus. The 
 abdominal cavity is lined anteriorly and posteriorly, 
 as well as on each side, by the parietal peritonaeum, 
 which is reflected on to the mesenteries, and thence 
 on to the gut, constituting the visceral layer of peri- 
 tonaeum (Fig. XX). 
 
Fig. XII. — A, Aorta. Ac, Alimentary canal. Pm, Pos- 
 terior mesentery. Am, Anterior mesentery. U, Um- 
 bilicus. 
 
28 ANATOMY OF THE PERITONEUM. 
 
 Fig. XIII. 
 
 The relation of the anterior mesentery is un- 
 changed by the development of the bend in the canal. 
 The posterior, however, presents a somewhat different 
 appearance. This mesentery appears to be shortened 
 where the inferior bend occurs. The stomach and the 
 first part of the small intestine have an anterior as 
 well as a posterior mesentery. The posterior mesen- 
 tery of the stomach is also called the mesogastriumo 
 
Am 
 
 u 
 
 Fig. XIIL— a, Aorta. S, Stomach. Pm, Posterior 
 mesentery or mesogastrium. Am, Anterior mesen- 
 tery, lb, Inferior bend. U, Umbilicus. 
 
30 ANATOMY OP THE PERITONEUM. 
 
 Fig. XIY. 
 The blood-vessels have been represented in this 
 plate to show that even at this earlj date the ves- 
 sels supplying the organs correspond to the vessels 
 in the adult — the cocliac axis, to supply the stom- 
 ach, liver, and spleen ; the superior mesenteric ar- 
 tery, to supply the caecum, ascending and transverse 
 colon ; the inferior mesenteric, to supply the de- 
 scending colon, sigmoid flexure, and rectum. 
 
Fig. XIV. — Oa, Coeliac axis. Sm, Superior mesenteric 
 artery. Iin, Inferior mesenteric artery. 
 
32 ANATOMY OF THE PERITONEUM. 
 
 Fig. XY. 
 
 The posterior mesentery is somewhat changed in 
 appearance by the crossing of the intestine. The 
 loop of intestine, with its mesentery, seems to be 
 separated from the posterior mesentery, yet it is not ; 
 its connecting band lies between the two parts of the 
 crossing intestine, but can not be seen in this plate. 
 The liver develops from the intestine and lies in the 
 anterior mesentery. The pancreas likewise originates 
 from the intestine, but lies in the posterior mesentery 
 or mesogastrium. 
 
Fig. XV. — Lo, Lesser omentum. S, Stomach. M, Meso- 
 gastrium. P, Pancreas. D, Diaphragm. L, Liver. 
 Am, Anterior mesentery. U, Umbilicus. 
 
34 ANATOMY OP THE PERITONEUM. 
 
 Fig. XYI. 
 
 Fig. XYI is an anterior view of the embryo, rep- 
 resenting the alimentary canal after the large has 
 fallen over the small intestine. In this plate the an- 
 terior mesentery has been entirely omitted, and all 
 the mesentery here seen is posterior mesentery. The 
 mesogastrium is attached to the median line ; it then 
 disappears behind the stomach ; it is again seen ap- 
 pearing from behind the stomach, to be attached to 
 its greater curvature. 
 
 It must be borne in mind that the stomach has 
 now materially altered its position. Its two ends 
 have approximated each other. It has so turned that 
 what was formerly its anterior border is now its lesser 
 curvature, and what was its posterior border is now 
 its greater curvature. We saw that the posterior 
 mesentery was attached to the posterior border of the 
 stomach and to the aorta. lN"ow, as the greater curva- 
 ture corresponds to what was the posterior border of 
 the organ, and as the mesogastrium has not changed 
 its place of attachment, we find it attached to the 
 greater curvature of the stomach. Moreover, what 
 was formerly the left surface of the stomach has now 
 become its anterior surface, and its right has become 
 its posterior surface. This would explain the distri- 
 bution of the left pneumogastric nerve to the ante- 
 rior and the right to the posterior surface of the 
 stomach. 
 
Fig. XVI. — A, Aorta. S, Stomach. M, Mesogastrmm. 
 Mc, Mesentery of colon. Mi, Mesentery of intes- 
 tine. Ms, Mesentery of sigmoid flexure. 
 
36 ANATOMY OF THE PERITONAEUM. 
 
 Fig. XYII. 
 If it is not easily understood how a portion of the 
 duodenum is hidden from view by the mesentery of 
 the transverse colon, any one can demonstrate it for 
 himself by the construction of a very simple mod- 
 el. Take a board and fasten to it an India-rubber 
 tube, bent in such a way as to resemble the bend in 
 the embryo intestine. A thin sheet of India-rubber 
 (such as dentists use for their rubber dam) makes a 
 very good posterior mesentery. This should be sewed 
 to the tube and attached to the surface of the board. 
 N^ow we have a side view of the embryonic aliment- 
 ary canal with its posterior mesentery. 
 
Fig. XVII.— B, Board. T, Tube. R, Eubber sheet. 
 
38 ANATOMY OF THE PERITONEUM. 
 
 Fig. XYIII. 
 
 The ascending portion of the bend should be ap- 
 proximated to the descending until the loop falls over, 
 and it will be seen that a part of the tube is covered 
 by the rubber sheet (the edge of the board corre- 
 sponding to the front of the embryo should now be 
 turned toward the observer). This sheet represents 
 the mesentery of the transverse colon, the covered 
 rubber tube the so-called third portion of the duo- 
 denum, and, in the model, now to see it one must 
 tear through the rubber sheet. Thus it is explained 
 how in the adult the jejunum seems suddenly to 
 appear in the abdomen, and the third portion of the 
 duodenum is invisible. This portion of the duol 
 denum is covered by the mesentery of the transverse 
 colon, and if this is cut through the duodenum wil- 
 come to light in the same way the tube did when the 
 rubber sheet was torn. 
 
Fig. XYIII. 
 
40 ANATOMY OF THE PERITONEUM. 
 
 Fig. XIX. 
 
 Fig. XIX is the same as Fig. XYI, only at a later 
 date. The mesogastrium is seen to be more devel- 
 oped, so that it forms quite a little sac behind and to 
 the left as well as below the stomach. After it has 
 reached this period of growth it is spoken of eitlier 
 as the posterior mesentery of the stomach, the meso- 
 gastrium, or the great omentum, the names being 
 applied to one aiid the same thing. The interior of 
 the sac — i. e., the space between the mesogastrium 
 and the stomach — is known as the lesser cavity of the 
 peritonaeum, or the cavity of the great omentum. 
 
Fig. XIX. — X, Line of section of Fig. XX. M, Meso- 
 gastrium. 
 
42 ANATOMY OF THE PERITONEUM. 
 
 MESENTERY OF THE INTESTINE IN 
 EMBRYO. 
 
 Fig. XX. 
 
 Suppose a transverse section of Fig. XIX be 
 made just below the transverse colon. We should 
 see the mesentery of the small intestine, as well as 
 the mesentery of the ascending and descending colon, 
 all attached posteriorly to the aorta ; the abdominal 
 cavity lined by the parietal peritonaeum ; the kidneys 
 lying external to it, in what is known as the retro- 
 peritoneal space (consequently they are covered only 
 on their anterior surfaces by peritonaeum). The im- 
 portant point is that both the large and small intes- 
 tines have a long and freely movable mesentery, and 
 are in no way fixed in the abdomen, except where 
 their mesenteries are attached to the aorta. This is 
 the actual condition of the intestines in the foetus, 
 and often even at birth. 
 
Pp-- 
 
 FiG. XX. — Si, Small intestine. M, Mesentery. C, Colon. 
 Mc, Ascending mesocolon. K, Kidney. A, Aorta. 
 Rs, Retroperitoneal space. Pp, Parietal peritonaeum. 
 
44 ANATOMY OF THE PERITONEUM. 
 
 Fig. XXI. 
 
 In the adult, however, it is different. The small 
 intestine remains unchanged, but tlie ascending and 
 descending colon become adherent to the posterior 
 abdominal wall. That is to say, the parietal peri- 
 tonaeum, as well as the peritonaeum on the posterior 
 surface of their mesenteries and a portion of the peri- 
 tonaeum on the colon itself, becomes changed to con- 
 nective tissue (represented in the plate in brown). 
 By means of this connective tissue the ascending and 
 descending colon, at or soon after birth, become im- 
 movably fixed to the posterior abdominal wall. It 
 explains, moreover, how it comes about that they are 
 only partially covered by peritonaeum, and how it is 
 possible in the adult, but not in a very young child, 
 to enter the ascending or descending colon posterior- 
 ly without injury to the peritonaeum. In this opera- 
 tion the operator would pass through the connective 
 tissue, and the peritoneal covering of the gut would 
 remain uninjured. It is interesting to note (speaking 
 generally) that the intestines of the higher animals as 
 regards this point resemble the condition found in the 
 foetus. 
 
Sf-~^. 
 
 Fig. XXI. — C, Colon. K, Kidney. Mc, Ascending 
 mesocolon. T, Connective tissue. Pp, parietal 
 peritonaeum. Si, Small intestine. 
 
46 ANATOMY OF THE PERITONEUM. 
 
 Fig. XXII. 
 
 In the adult, as was just explained, the mesentery 
 of the descending colon becomes attached to the pos- 
 terior abdominal wall. The mesentery of the sigmoid 
 flexure, however, is usually only attached, as in the 
 embryo, to the median line, and does not unite with 
 the peritonaeum of the posterior abdominal wall. It 
 is long, and consequently very movable — so much so 
 in fact that the ancients described the normal position 
 of sigmoid flexure to be on the right side of the body. 
 An unattached sigmoid flexure is the rule, but to find 
 it more or less united is not uncommon. 
 
 Fig. XXII represents the descending colon and 
 sigmoid flexure with their mesenteries. The dotted 
 line shows the limit, inferiorly, to which the mesen- 
 tery of the descending colon is attached to the poste- 
 rior abdominal wall. As the sigmoid flexure is not 
 usually attached here, but is quite movable, one is able 
 to lift it up, and will find on so doing a more or less 
 triangular cavity or fossa beneath it. This fossa is 
 bounded in the median line by the attached mesentery 
 of the sigmoid flexure, and above by the dotted line 
 representing the limit of the attachment of the mesen- 
 tery of the descending colon. It is called the sub- 
 sigmoid fossa. Its size depends upon the extent of at- 
 tachment of the mesentery of the sigmoid flexure to the 
 posterior abdominal wall. If this line of attachment 
 extends lower down than normal, so as to include a 
 part of the sigmoid flexure, the fossa will be poorly 
 developed ; if, on the other hand, the entire mesentery 
 of the sigmoid flexure is free, the fossa will be large. 
 
Fig. XXII. — A, Aorta. Dc, Descending colon. Mc, 
 Descending mesocolon. Sm, Sigmoid mesocolon. 
 Sf, Sigmoid flexure. 
 
48 ANATOMY OF THE PERITONEUM. 
 
 MESENTERIES OF THE LIVER AND 
 STOMACH. 
 
 Fig. XXIII. 
 
 In a median section of a young embryo the liver 
 is seen developing in the anterior mesentery of the 
 stomach and duodenum. It divides this mesentery 
 into what is called the anterior mesentery of the liver 
 and the anterior mesentery of the stomach or lesser 
 omentum. From the first moment the liver is dis- 
 tinguishable it is connected not only to the intestine, 
 but also to the diaphragm. It is, in fact, a part of 
 the latter, and it is of the utmost importance to 
 always think of it as an appendage to the diaphragm, 
 and at no period of life separate from it. The pan- 
 creas is seen developing in the mesogastrium. 
 
Am- 
 
 FiG. XXIII. — Lo, Lesser omentum. S, Stomach. M» 
 Mesogastrium. P, Pancreas. D, Diaphragm. L, 
 Liver. Am, Anterior mesentery. U, Umbilicus. 
 
50 ANATOMY OF THE PERITONEUM. 
 
 Fig. XXIV. 
 
 A transverse section through the stomach of the 
 same embryo would present this picture: The peri- 
 toneal cavity lined by its parietal peritonaeum ; the 
 stomach connected with the posterior abdominal wall 
 by its mesogastrium or greater omentum ; with the 
 liver by its anterior mesentery or lesser omentum ; 
 and, lastly, the liver connected with the anterior ab- 
 dominal wall by its anterior mesentery. 
 
Am 
 
 Fig. XXIV. — Am, Anterior mesentery of liver. L, 
 Liver. S, Stomach. Lo, Lesser omentum. Pp, 
 Parietal peritonaeum. M, Mesogastrium. 
 
52 ANATOMY OF THE PERITONEUM. 
 
 Fig. XXY. 
 
 This sketch differs from the last in that the em- 
 bryo is older, and consequently the organs are more 
 developed. The stomach and liver present much the 
 same appearance as in the last drawing, but the pan- 
 creas has been included in this plate. The mesogas- 
 trium is longer — it seems curved — and, what is very 
 important, is the appearance of the spleen. This 
 organ is not only developed in, but also from, the 
 mesogastrium. 
 
fMTK^ 
 
 
 
 
 "/^\ ^^7^^ 
 
 D 
 
 1 '^^^^,^1) 
 
 
 'pi ->S 
 
 
 M' 
 
 Pig. XXV.— L, Liver. S, Stomach. Sp, Spleen. P, 
 Pancreas. Am, Anterior mesentery. Lo, Lesser 
 omentum. M, Posterior mesentery. 
 
54 ANATOMY OF THE PERITONEUM. 
 
 Fig. XXYI. 
 A sagittal section of an embryo about the same 
 age as in the last sketch would present this appear- 
 ance: In Fig. XXY the great omentum was devel- 
 oping laterally, and now it is seen also to have grown 
 downward as well, so as to form a distinct sac. The 
 pancreas has been met in the section, and is contained 
 within the mesogastrium. 
 
Fig. XXVI.— L, Liver. P, Pancreas. Pp, Parietal 
 peritonaeum. Go, G-reat omentum or mesogastrium. 
 S, Stomach. Lo, Lesser omentum. D, Diaphragm. 
 Co, Cavity of greater omentum. 
 
56 ANATOMY OF THE PERITONEUM. 
 
 Fig. XXYII. 
 
 A very diagrammatic view of only the greater 
 omentum and the stomach, seen from before, may 
 make the last two drawings plainer. It must always 
 be borne in mind that the change in the position of 
 the stomach (as described on page 34) has materially 
 altered the direction of the omenta. They both pass 
 much more in a transverse, inferior direction than 
 they formerly did. Moreover, the great omentum, 
 although still attached ^posteriorly to the median line, 
 has developed very much to the left, as well as in- 
 feriorly. It does not, in other words, make a straight 
 line between the aorta and greater curvature of the 
 stomach, but passes to the left of the stomach, de- 
 scends, and then ascends once more to attach itself to 
 the greater curvature, and in this way forms the sac, 
 as before mentioned, which is the cavity of the great 
 omentum or lesser cavity of the peritonaeum. 
 
— M 
 
 Fig. XXVII. — S, Stomach. M, Posterior mesentery, 
 mesogastrium, or great omentum. 
 
58 ANATOMY OP THE PERITONEUM. 
 
 Fig. XXYIII. 
 Owing to the mentioned change in the position of 
 the stomach, as well as to a further development in 
 the shape of the organs, this section differs materially 
 from the last. The section has passed between the 
 liver and stomach, dividing the lesser omentmn. 
 This seems to be attached to the greater curvature or 
 to the posterior surface of the stomach, but this is not 
 the case. It is still attached to the lesser curvature, 
 the erroneous impression being due to the change in 
 the position of the stomach, and consequently a 
 change in the direction of the lesser omentum. The 
 spleen is seen as before, but more developed, and the 
 lateral inclination of the great omentum is marked. 
 The pancreas is still surrounded by the peritonaeum, 
 derived from the great omentum, but it is now rest- 
 ing upon the parietal peritonaBum. This picture 
 would correspond to the condition of the pancreas 
 just before birth, or, at times, in a very young child 
 — enveloped by the peritonaeum of its mesentery, 
 and resting upon the posterior parietal peritonaeum. 
 The position of the kidneys is unchanged. They lie 
 in the retroperitoneal space. 
 
^Lo 
 
 Fig. XXVIII.— E, Round ligament of the liver. S, 
 Stomach. Lo, Lesser omentum with vessels going 
 to the liver. K, Kidney. P, Pancreas. Sp, Spleen. 
 Go, Great omentum. 
 
60 ANATOMY OF THE PERITONAEUM. 
 
 Fig. XXIX. 
 
 The change at this stage is marked, and corre- 
 sponds to what is generally found at birth. The 
 layer of parietal peritonaeum posterior to the pan- 
 creas, as well as the visceral layer on its posterior 
 surface, derived from the mesogastrium, have been 
 changed to connective tissue. The pancreas has con- 
 sequently entirely lost its posterior peritoneal cover- 
 ing. The spleen and stomach are more developed, 
 and the great omentum extends still farther to the 
 left. It has now increased laterally to such an extent 
 that it forms quite an extensive sac behind the stom- 
 ach, which, as was before mentioned, is known as the 
 lesser cavity of the peritonaeum. Between the vessels 
 going to the liver and the aorta this lesser cavity con- 
 nects with the greater peritoneal cavity, or, in other 
 words, with the rest of the abdominal cavity. The 
 connection is made through a restricted opening 
 bounded anteriorly by the vessels going to the liver 
 in the lesser omentum and posteriorly by the aorta 
 (or, more accurately, by the vena cava, which is not 
 drawn in). This opening is the foramen of Winslow. 
 
Sp- 
 
 FiG. XXIX. — R, Round ligament of the liver. Lo, Less- 
 er omentum. Fw, Foramen of Winslow. K, Kid- 
 ney. T, Connective tissue. P, Pancreas. Sp, 
 Spleen. Go, Great omentum. 
 
62 ANATOMY OF THE PERITONEUM. 
 
 Fig. XXX. 
 
 A sagittal section of a child at or just before birth 
 would present this appearance : The liver united to 
 the diaphragm and covered by the parietal perito- 
 naeum, reflected from the diaphragm as well as by 
 the visceral peritonaeum reflected from the lesser 
 omentum; the lesser omentum between liver and 
 stomach ; the stomach covered by peritonaeum de- 
 rived from its mesenteries (the greater and lesser 
 omentum) ; the great omentum extending downward 
 from the greater curvature of the stomach and form- 
 ing the downward projection of the lesser cavity 
 of the peritonaeum ; the pancreas lying behind the 
 peritonaeum (the parietal peritonaeum posterior to it 
 as well as its posterior visceral layer, derived from 
 the great omentum, is seen to have changed to con- 
 nective tissue). The pancreas is now only covered on 
 its anterior and inferior surfaces by peritonaeum, both 
 derived from the great omentum. The transverse 
 colon is here drawn in with its mesentery. 
 
Fig. XXX.— L, Liver. Lo, Lesser omentum. T, Con- 
 nective tissue. P, Pancreas. 0, Colon. D, Dia- 
 phragm. S, Stomach. Go, Great omentum. Co, 
 Cavity of great omentum. 
 
64 ANATOMY OF THE PERITONEUM. 
 
 Fig. XXXI. 
 At or soon after birth the picture is somewhat 
 modified. The posterior layer of the great omentum 
 has become adherent to the transverse colon and its 
 mesentery, so that, were the greater omentum lifted 
 up, the colon would be raised with it. By the union 
 of the great omentum with the transverse mesocolon 
 the inferior surface of the pancreas becomes covered 
 by the latter, its former peritoneal covering, derived 
 from the great omentum, having been changed to 
 connective tissue. So it is now covered anteriorly by 
 the great omentum, and inferiorly by the transverse 
 mesocolon. 
 
Go- 
 
 Fig. XXXI. — Lo, Lesser omentum. P, Pancreas. T, 
 Connective tissue. C, Colon. Tm, Transverse 
 mesocolon. Go, Great omentum. L, Liver. D, 
 Diaphragm. 
 
ee ANATOMY OF THE PERITONEUM. 
 
 Fig. XXXII. 
 
 A transverse section of the abdomen of an adult 
 which passes through tlie stomach shows a further ex- 
 tension of the great omentum to the left and a greater 
 production of connective tissue behind it where it be- 
 comes adherent to the abdominal wall. This connect- 
 ive tissue covers the left kidney, and in the adult can 
 usually be demonstrated on the left side as a distinct 
 layer, which is entirely absent on the right. 
 
.-Lo 
 
 Fig. XXXII. — S, Stomach. Sp, Spleen. P, Pancreas. 
 Lo, Lesser omentum. Go, Great omentum. T, 
 Connective tissue. Fw, Foramen of Winslow. R, 
 Round ligament of liver. 
 
68 ANATOMY OF THE PERITONEUM. 
 
 DUODENUM. 
 
 Fig. XXXIII. 
 
 Fig. XXXIII is a transverse section of the duo- 
 denum in embryo. At this period the entire duo- 
 denum has a posterior mesentery, and is covered by 
 peritonseum. The first portion has also an anterior 
 mesentery. In the adult this portion is entirely 
 covered by peritonaeum derived from its mesenteries. 
 The anterior mesentery is a part of the lesser omen- 
 tum, and is often called the hepatico-duodenal Hga- 
 ment. 
 
Fig. XXXIII. — Du, Duodenum in embryo. Pm, Pos- 
 terior mesentery. 
 
70 ANATOMY OP THE PERITONEUM. 
 
 Fia. XXXIY. 
 
 Fig. XXXIY represents a transverse section of 
 the second portion of the duodenum after birth. The 
 parietal peritonaeum behind the second portion (some 
 little time before birth), as well as the posterior peri- 
 tonseum of its mesentery, are changed to connective 
 tissue, so that at an early date the second portion of 
 the duodenum is only partially covered by the peri- 
 tonseum. 
 
Fig. XXXIV. — Du, Second portion of adult duodenum. 
 T, Connective tissue. 
 
72 ANATOMY OF THE PERITONEUM. 
 
 Fig. XXXY. 
 
 To understand the third portion we shall have to 
 return to a joung embryo, and to that period of de- 
 velopment when not only the transverse colon is un- 
 united with the posterior layer of the great omentum, 
 but when the pancreas is in the great omentum. At 
 this date, as was before mentioned, the duodenum has 
 its posterior mesentery. 
 
Fig. XXXV.— L, Liver. P, Pancreas. Du, Duodenum. 
 
 C, Colon. Go, Great omentum. S, Stomach. D, 
 Diaphragm. 
 
74 ANATOMY OF THE PERITONEUM. 
 
 Fig. XXXYl. 
 
 This plate is the same as Fig. XXX, except that 
 the duodenum is represented. It still has its mesen- 
 tery. The transverse colon has not yet united with the 
 posterior layer of the great omentum, so the pancreas 
 is covered anteriorly as well as inferiorly by the peri- 
 tonaeum of the great omentum. 
 
Fig. XXXVI. — L, Liver. T, Connective tissue. Du, 
 Duodenum. C, Colon. Go, Great omentum. S, 
 Stomach. Lo, Lesser omentum. P, Pancreas. 
 
76 ANATOMY OF THE PERITONEUM. 
 
 Fig. XXXYII. 
 
 At a still later date — not only after the ascending 
 and descending colons have become adherent to the 
 posterior abdominal wall, but also after the transverse 
 colon and mesocolon have united with the great 
 omentum — the parietal peritonaeum posterior to the 
 third portion of the duodenum is changed to con- 
 nective tissue, as well as the visceral layer on its pos- 
 terior surface. [It must always be borne in mind 
 that, by means of the turn in the intestine, that this 
 portion of the duodenum lies posterior to the trans- 
 verse mesocolon.] Its anterior and superior visceral 
 layers unite with the transverse mesocolon, and are 
 changed to connective tissue. 
 
 In this way the third portion of the duodenum 
 loses its peritoneal covering and comes to lie behind 
 the peritonaeum in the retro-peritoneal space, as well 
 as posterior to, and covered anteriorly by, the trans- 
 verse mesocolon. 
 
Fig. XXXVII.— 01, Coronary ligament. Du, Duode- 
 num. Tm, Transverse mesocolon. Si, Small in- 
 testine. 0, Colon. P, Pancreas. T, Connective 
 tissue. Go, Great omentum. 
 
78 ANATOMY OF THE PERITONEUM. 
 
 STOMACH. 
 
 In the embryo this organ possesses an anterior and 
 a posterior mesentery. The anterior is attached to 
 the median hne of the abdominal wall and to the an- 
 terior border of the stomach ; the posterior mesen- 
 tery to the aorta and to the posterior border of the 
 stomach (Fig. XIII). Later, through the change in 
 the position of the organ, the anterior mesentery, or 
 gastro-hepatic ligament, is attached to the lesser curv- 
 ature; the posterior mesentery, or mesogastrium, to 
 the greater curvature. These two mesenteries are 
 also called the lesser and greater omentum, respect- 
 ively. The former is the mesentery of the liver, the 
 latter the mesentery of the spleen, pancreas, and 
 stomach (Figs, XXIY and XXYI). At a still later 
 date the great omentum ceases to pass in a direct 
 line from its aortal attachment to the greater curva- 
 ture, but makes a bend to the left and extends down- 
 ward below the stomach, returning to be attached to 
 the greater curvature. 
 
 Thus the great omentum forms a sac which ex- 
 tends posteriorly, to the left, and below the stomach 
 (Fig. XXYIII). This sac is known as the lesser 
 cavity of the great omentum, and communicates with 
 the greater peritoneal cavity by means of the foramen 
 of Winslow. This foramen is situated inferior to the 
 
SPLEEN. 79 
 
 caudate lobe of the liver, posterior to the lesser omen- 
 tum, and anterior to the vena cava (Fig. XXIX). It 
 might be mentioned that more or less fat is developed 
 in the descending and ascending layers of the great 
 omentum, which forms a protection to the intestines. 
 After the adhesion of the transverse colon to the 
 great omentum a further adhesion of its two leaves 
 takes place, and so obliterates the cavity of the great 
 omentum inferior to the transverse colon. The stom- 
 ach at all periods of life is covered by reflections of 
 visceral peritonaeum derived from its mesenteries. 
 
 It might be well here to repeat that the posterior 
 mesentery of the stomach is a synonym for mesogas- 
 trium, and that after it has developed suflficiently to 
 form a sac it is called the great omentum. The an- 
 terior mesentery of the stomach, gastro-hepatic liga- 
 ment, and lesser omentum, are also synonyms. 
 
 SPLEEIS". 
 
 The spleen is developed from as well as in the 
 mesogastrium. It is at all times entirely surrounded 
 by the visceral peritonaeum derived from its mesen- 
 tery (Figs. XXY, XXYIII, and XXXII). That por- 
 tion of the great omentum between the spleen and 
 stomach is often referred to as the gastro-splenic liga- 
 ment. 
 
80 ANATOMY OF THE PERITONEUM. 
 
 PANCREAS. 
 
 This organ originates from the intestine, and is 
 developed in the mesogastrium (Figs. XV, XXYII, 
 and XXXY). 
 
 In the embryo it is surrounded by peritonaeum 
 derived from its mesentery. Later the parietal peri- 
 tonaeum posterior to it, as well as its posterior visceral 
 layer, become changed to connective tissue, and in 
 this way it entirely loses its posterior peritoneal 
 covering (Fig. XXIX). After the union of the trans- 
 verse colon and its mesentery with the posterior 
 layer of the great omentum, the visceral layer, cover- 
 ing the inferior surface of the pancreas, is changed to 
 connective tissue ; so that in an adult we find the 
 pancreas covered anteriorly by the peritonaeum of the 
 great omentum, inferiorly by the transverse meso- 
 colon, and lying in the retroperitoneal space (Figs. 
 XXXII and XXXI). 
 
 LIVER. 
 
 The liver originates in a sprout-like process from 
 the intestine, it is developed in the anterior mesen- 
 tery, and at all periods of life is inseparable from the 
 diaphragm. It should be considered, as it really is, a 
 part of it. If we think of the liver in this way, as 
 
LIVER. 81 
 
 a portion of the diaphragm, not only in the embryo, 
 but also in the adult, our difticulties in understanding 
 the so-called ligaments of the liver will be materially 
 diminished (Fig. XY). The inferior surface of the 
 diaphragm is covered by parietal peritonaeum, which 
 is reflected over the liver, and these reflections form 
 some of its ligaments. The gall-bladder is developed 
 by a sprouting process from the gall-duct, and is a 
 part of the liver, just as the liver is a part of the dia- 
 phragm. The liver is consequently entirely covered 
 by peritonseum, which is derived from the parietal 
 peritonaeum on the inferior surface of the diaphragm, 
 as well as from reflections of visceral peritonaeum de- 
 rived from its mesenteries (Fig. XXXYII). Should 
 we dissect the gall-bladder from the liver, or the liver 
 from the diaphragm, on their attached surfaces there 
 would be no peritoneal covering, any more than there 
 would be if we made a section through the liver and 
 expected to find peritonaeum on its cut surface. 
 
ANATOMY OF THE PERITONEUM. 
 
 Fig. XXXYIII. 
 
 This figure represents the so-called posterior sur- 
 face of the liver after it has been artificially separated 
 from the diaphragm. (The posterior surface is con- 
 vex, but here has been represented as flat, for the 
 sake of clearness.) Around its diaphragmatic or 
 posterior surface are seen the cut edges of some of 
 the ligaments, which, to repeat, are mostly reflections 
 of peritonaeum from the diaphragm. Two of these 
 layers are described as the coronary ligaments, and 
 are attached to the superior and inferior borders of 
 this surface. They end in more or less pointed 
 processes, one on each lobe, to which the name lat- 
 eral ligament has been given, though they are simply 
 continuations of the coronary. Moreover, the ante- 
 rior mesentery can be seen, and it is the remains of 
 this mesentery which forms the suspensory ligament. 
 It extends from the diaphragm to the superior sur- 
 face of the liver, and from the anterior abdominal 
 wall to its anterior border. The umbilical vein 
 limits the anterior mesentery inferiorly. In fact, it 
 is contained in its folds, surrounded by it, but not 
 completely, for on its anterior surface it is destitute 
 of peritoneal covering (Fig. XXYIII). This vein in 
 the embryo enters the umbilical fissure on the inferior 
 surface of the liver, and is continued by means of the 
 ductus venosus to the vena cava, which is situated on 
 its so-called posterior surface. After birth these 
 veins are obliterated, and constitute the remains of 
 the ductus venosus and the round ligament of the 
 liver. In the drawing, between the ductus venosus 
 and vena cava, the Spigelian lobe is seen, which is, of 
 course, covered by peritonaeum, as it is a part of the 
 free surface of the organ. 
 
Fig. XXXVIII. — Vc, Yena cava. Sc, Superior coronary 
 ligaments. Ic, Inferior coronary ligaments. S, 
 Spigelian lobe. All, Right lateral ligament. Lll, 
 Left lateral ligament. SI, Suspensory ligament 
 (anterior mesentery). Dv, Ductus venosus. X, 
 Diaphragmatic or posterior surface of liver which 
 is uncovered by peritonaeum. 
 
84: ANATOMY OF THE PERITONEUM. 
 
 JEJUNUM AND ILIUM. 
 
 These portions of the small intestine have a me- 
 sentery, are freely movable, and are at all periods of 
 life covered by peritonaeum (Fig. XXI). 
 
 C^CUM. 
 
 The relation of the peritonaeum to the caecum is 
 very variable. It has a mesentery, which may be 
 long, but is more often short, and the caecum is com- 
 pletely covered by peritonaeum. It may, however, 
 become adherent to the side of the abdominal wall, 
 and the parietal as well as a part of its visceral layers 
 may be changed to connective tissue ; in which case 
 it would be only partially covered. 
 
 ASCENDING AND DESCENDING COLONS. 
 
 In the embryo the ascending and descending 
 colons have a long, free mesentery. They are quite 
 movable, and entirely covered by peritonaeum (Fig. 
 XX). Just before birth the colon with its mesentery 
 becomes adherent to the posterior parietal perito- 
 naeum. The latter is changed to connective tissue 
 as well as the visceral layer on the posterior surface 
 of the mesocolon and colon. In this way the colon 
 
TRANSVERSE COLON. 85 
 
 becomes fixed to the posterior abdominal wall, and is 
 only partially covered by peritonaeum (Fig. XXI). 
 
 TRANSVERSE COLON. 
 
 This, like the other portions of the large intestine, 
 in the embryo has a long mesentery ; is Yory mov- 
 able, and is covered by peritonaeum (Fig. XXXYI). 
 Later, after the development of the great omentum, 
 the visceral peritonaeum on the superior surface of 
 the transverse mesocolon, as well as that on the colon, 
 becomes changed to connective tissue and adheres to 
 the posterior layer of the great omentum. Its an- 
 terior surface is then covered by the visceral peri- 
 tonaeum of the posterior layer of the great omen- 
 tum. Its posterior surface remains unchanged (Fig. 
 XXXYII). So the transverse colon at all periods 
 of life is covered by peritonaeum. 
 
 SIGMOID FLEXURE. 
 
 The mesentery of the sigmoid flexure is attached 
 to the aorta, and is usually long and movable. The 
 gut is entirely covered by peritonaeum. 
 
86 ANATOMY OP THE PERITONJSUM. 
 
 EEOTUM. 
 
 The first portion of the rectum has a mesentery 
 attached to the median line. The organ is entirely 
 covered by peritonaeum. The posterior visceral peri- 
 tonaeum on the second portion of the rectum is 
 changed to connective tissue, so that the organ be- 
 comes fixed, and is only partially covered by peri- 
 tonaeum. The third portion of the rectum is desti- 
 tute of peritoneal covering. 
 
 KIDNEY. 
 
 At all periods of life these organs lie behind the 
 peritonaeum in the retroperitoneal space (Figs. XX, 
 XXI, and XXXII). 
 
 There is nothing further to add, as regards the 
 relation of the peritonaeum to the rectum, uterus, and 
 bladder, than is given in the text-books of anatomy. 
 
 THE El^D. 
 
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