PERITONEUM. 



93 9 



rived they finally separate, partially investing, as 

 they do so, the transverse portion of the duode- 

 num. Thus both layers reach the abdominal 

 parietes along the continuous line of attachment 

 of the splenic omentum and the transverse me- 

 socolon ; the internal layer from this continuous 

 line invests the pancreas and other parts behind 

 the stomach, then thelobulus Spigelii, and thus 

 is conducted to the posterior surface of the 

 lesser omentum, from which we started. The 

 external layer of the omental sac, having reached 

 this line of parietal attachment as part of the 

 splenic omentum to the left, passes off on the 

 left kidney and the lateral abdominal parietes 

 and diaphragm ; having reached it below as 

 the transverse mesocolon, it may thence be 

 traced downwards to the root of the mesentery. 

 The small intestine is enclosed in the extre- 

 mity of the fold of a duplicature of peritoneum. 

 That part of the fold which extends across from 

 the posterior parietes to the intestine is called 

 the mesentery. The two component layers of 

 the mesentery are adherent by their apposed 

 surfaces, except where vessels, &c. intervene, so 

 that it is a parieto-visceral sheet with two free 

 surfaces. The parietal attachment of the me- 

 sentery is called its root, and extends obliquely 

 across the spine from the left side of the second 

 lumbar vertebra, where the duodenum emerging 

 from the root of the transverse mesocolon be- 

 comes jejunum, to the right iliac fossa, where 

 the ilium enters the coecum. Though the pa- 

 rietal attachment or root of the mesentery is but 

 a few inches in length, its visceral attachment 

 by means of numerous ample foldings, like a 

 ruffle, corresponds in length with the twenty 

 feet of small intestine. Tracing, then, the peri- 

 toneum heretofore forming the external layer of 

 the great omental sac from the point where it 

 reaches the posterior parietes as part of the 

 transverse mesocolon, downwards, we come to 

 that side of the root of the mesentery which 

 looks upwards and to the right ; thence we 

 trace this surface continuous along the mesen- 

 tery, over the bowel, back again along the other 

 side of the mesentery, so reaching that side of 

 its root whose aspect is downwards and to the 

 left ; in both which directions the peritoneum 

 may be traced onwards. To the left it reaches 

 the right side of the descending colon, invests 

 the front of that bowel, and passes off on the 

 other side of it to the lateral parietes : occa- 

 sionally only does it dip beneath the descending 

 colon so as to come in contact with itself and 

 form a mesentery for it. A little lower down, 

 however, namely, in the left iliac fossa, it always 

 forms a mesentery for the sigmoid flexure of 

 the colon, and, still lower down, for the first 

 part of the rectum. The distinction, however, 

 between iliac mesocolon and mesorectum, as 

 the mesenteries of the sigmoid flexure and rec- 

 tum are called, is quite arbitrary and unnatural ; 

 a continuous mesenteric duplicature, broad in 

 the middle and tapering to each end, serves to 

 give attachment to both the sigmoid flexure and 

 the first part of the rectum. Proceeding from 

 the root of the mesentery downwards in the 

 middle line, the peritoneum covers the sacro- 

 vertebral prominence, and, just below, it ar- 



rives at the rectum and forms a mesentery for 

 its first portion as above stated. The perito- 

 neum invests the front only of the second por- 

 tion of the rectum, and at a variable distance 

 from the anus quits it and extends across to the 

 back of the bladder in the male, or vagina and 

 uterus in the female, so that the lowermost por- 

 tion of the rectum is destitute altogether of pe- 

 ritoneal investment. 



From the other side of the root of the me- 

 sentery, namely, that which looks upwards and 

 to the right, we may trace the continuity of 

 peritoneal surface off to the right lumbar region, 

 investing the ascending colon in a like, and 

 similarly variable, manner to that in which it 

 was described as investing the descending co- 

 lon ; and to the right iliac fossa, where it invests 

 the coecum, sometimes, but not most frequently, 

 forming a narrow mesentery for it called the 

 meso-coacum. A bit of mesentery is usually 

 afforded to the vermiform process, but this, of 

 course, we do not reach by proceeding off late- 

 rally from the last-mentioned aspect of the root 

 of the mesentery. 



As mentioned above, the peritoneum extends 

 across from the front of the rectum to the back 

 of the bladder, in the male subject; the level 

 at which it does so varies with the state of full- 

 ness or emptiness of the bladder, and also is 

 said to vary, cseteris paribus, in different indi- 

 viduals ; frequently it is so low that the peri- 

 toneum, passing across, touches the prostate. 

 This is in the middle, between the front of the 

 rectum and back of the bladder, but laterally 

 the peritoneum is elevated into two antero- 

 posterior folds, which extend across from the 

 sides of the rectum to the sides of the bladder ; 

 these are called the recto-vesical folds or pos- 

 terior ligaments of the bladder: anterior and 

 external to them there are two other small 

 folds. External to the recto-vesical folds the 

 peritoneum does not descend nearly so low as 

 it does between them ; and therefore there is a 

 remarkable, deepish, cul-de-sac, of the same 

 breadth as the rectum, between that intestine 

 and the bladder. 



The posterior and lateral aspects and fundus 

 of the bladder are invested with peritoneum, 

 but not its anterior aspect : the peritoneum 

 passes from the fundus of the bladder, by an 

 even slant, on to the anterior abdominal pari- 

 etes, not making any dip in front of it except 

 when it is much distended. In the female 

 there is a deep cul-de-sac of peritoneum be- 

 tween the rectum and uterus, descending low 

 enough to be in contact with the vagina : 

 between the uterus and bladder there is a 

 second but much shallower cul-de-sac. 



We have now traced the peritoneum over 

 the ascending and descending portions of the 

 colon to the abdominal parietes in the right 

 and left lumbar region ; from the recto-vesical 

 folds and sides of the bladder to the iliac 

 fossa ; and from the fundus of the bladder to 

 the anterior abdominal parietes of the hypo- 

 gastric region; from all or any of these posi- 

 tions, or from any point between them, we 

 may trace the peritoneal free surface uninter- 

 ruptedly up to our first starting point, the 



