936 



PERITONEUM. 



arteries, its veins, its nerves, and its lymphatics 

 passing to and from it, and the whole must be 

 invested by a single shut sac without loss of 

 continuity. The complexity thus arising de- 

 mands for this membrane a lengthened descrip- 

 tion. 



We propose, first, to trace its continuity 

 throughout its entire extent; next, to describe 

 the sheets with two free surfaces, which it 

 forms by duplication ; thirdly, to examine the 

 manner in which it invests each of the viscera, 

 and the abdominal parietes, that is to say, the 

 extent to which it does so in the case of each, 

 the point at which it arrives at and quits each, 

 and so on ; and, lastly, to describe its con- 

 nexions, or the adhesion of its external surface, 

 varying in intimacy, with the parts which it 

 invests. The most important points connected 

 with the anatomy of the peritoneum will be 

 incidentally involved in the consideration of 

 the first of these propositions. 



CONTINUITY OF THE PERITONEUM. To 

 demonstrate the unbroken continuity of the 

 peritoneum, we are compelled, in description, 

 to trace it in various directions, starting 

 from a certain point and following it up till, 

 having performed a complete circuit, we 

 return again to our starting point. In doing 

 so we shall avoid restricting ourselves to the 

 mesial or any other sectional line. We believe 

 that such a restriction, closely adhered to, 

 tends to convey an erroneous impression, 

 namely, that of a line instead of a superficial 

 expanse. In thus tracing the peritoneum, it 

 is better to let the mind rest upon the idea of a 

 free surface, rather than upon that of a mem- 

 brane. By a membrane one is apt to under- 

 stand a separable skin ; but in some situations 

 not only is it impossible, by any ordinary ma- 

 nipulation, to separate the peritoneum from its 

 connections, but two layers of it often form 

 together a structure so thin that one can hardly 

 help regarding it as a single membrane. In 

 no instance is any part of a serous membrane 

 free on both its surfaces. The external surface 

 of the peritoneum, like that of all other serous 

 sacs, is every where adherent, either to the sub- 

 jacent structures, or, as in its duplications, to 

 itself; whilst, on the other hand, its internal 

 surface is, normally, every where free. It 

 follows then, that wherever, in the peritoneal 

 cavity, the finger can be placed on a free sur- 

 face, there is a layer of peritoneum immedi- 

 ately beneath it ; that if a continuous free 

 surface is demonstrated, the continuity of the 

 serous membrane is proved ; that in fact a free 

 serous surface represents a layer of serous 

 membrane, and may be described instead of it 

 when continuity alone is sought to be proved. 

 We shall therefore at present use the expres- 

 sions free surface and layer of serous mem- 

 brane as synonymous ; the free surface of a 

 viscus instead of the serous membrane invest- 

 ing a viscus. 



When the abdominal cavity is laid open in 

 front by a crucial incision, the inner surface of 

 the reflected flaps is seen to be free, glistening, 

 and of a pale red colour. By a slight exami- 



nation of the cut edges this is found to be the 

 free surface of a membrane, whereof the other 

 surface is connected to the subjacent structures 

 by areolar tissue : the free surface is the parietal 

 serous surface of the abdomen: the membrane 

 is the parietal portion of the peritoneum. If 

 an incision has been carried from the navel to 

 the xiphoid cartilage, a falciform, membrane- 

 like process, strikingly resembling the froenum 

 linguae, is seen connected with the anterior 

 parietal peritoneum, a little to the right of the 

 middle line, projecting backwards, and towards 

 that aspect presenting a free concave border. 

 It is the falciform ligament of the liver. The 

 base or broadest extremity of the falx is sessile 

 along an antero-posterior line upon the upper 

 surface and anterior edge of the liver ; which 

 line corresponds with and runs into the great 

 antero-posterior fissure on the under surface of 

 the liver; and this fissure receives the round 

 ligament, and consequently the free edge of 

 the falx which encloses it. The apex of the 

 falx is at a point on the inner surface of the 

 anterior abdominal parietes, corresponding to 

 the navel. The surfaces of the falciform liga- 

 ment are continuous with the serous surfaces of 

 the parietes and liver ; its free border, as inci- 

 dentally mentioned above, encloses a structure 

 called the round ligament of the liver, which 

 gives a considerable thickness to this part. 



The round ligament of the liver is the umbi- 

 lical vein of the fcetus, degenerated to a fibrous 

 cord in the adult, and it runs across, as that 

 vein did, from the navel to the antero-posterior 

 fissure of the liver, defining the free border of the 

 falciform process in question. The composition, 

 then, of the falciform ligament of the liver is 

 a portion of peritoneum doubled or folded, so 

 that its outer surface is brought in contact with 

 itself, as happens when asheet of paper is folded 

 so as to make two leaves. The two surfaces 

 thus brought into contact, are united together 

 by areolar tissue, as if the two leaves were 

 stuck together with paste ; and the round liga- 

 ment lies along in the extreme edge of the fold, 

 like a string that holds a sheet of two leaves in 

 a book-cover. The vessels necessary for the 

 nutrition of these structures ramify in the in- 

 terposed areolar tissue. It seems as if the 

 umbilical vein, in making the shortest route 

 from the navel to the longitudinal hepatic fis- 

 sure, had carried back before it a fold of the 

 superjacent peritoneum. 



We have spent more time in describing this, 

 the first peritoneal fold we have come to, than 

 is due to its importance, because it affords us, 

 that which we want in this early stage of our 

 description, an instance of the manner in which 

 the peritoneum invests the various organs, 

 having the advantage of extreme simplicity. 

 A bowel is invested by the peritoneum and it 

 occupies a situation in a fold precisely analo- 

 gous to that which the round ligament occupies 

 in the falciform ligament; whilst the vessels 

 and nerves of the bowel pass to and from it 

 imbedded in the areolar tissue uniting the ap- 

 posed surfaces. 



Placing a finger of each hand on each side 



