ABDOMEN. 



ABDOMEN (in human anatomy.) In ex- 

 amining the human skeleton, we notice that 

 from the apex of the thorax to the inferior out- 

 let of the pelvis, there exists one great oblong 

 excavation. The two superior fifths of this 

 cavity are separated from the remaining portion 

 in the entire subject by a musculo- tendinous 

 lamella, which, thrown into a vaulted form, 

 constitutes the partition between the cavity of 

 the thorax above and that of the abdomen below. 

 This latter cavity communicates inferiorly with 

 the space circumscribed by the ossa innominata, 

 denominated the cavity of the pelvis ; nor is 

 there any natural line of demarcation between 

 the two cavities. The communication between 

 the two cavities is as free in the recent subject 

 as it is in the skeleton, and under various con- 

 ditions the contents of those cavities pass from 

 the one to the other. A plane extended hori- 

 zontally from the linea iliopectinea on one side 

 to the corresponding line on the other would 

 constitute an artificial floor to the cavity of the 

 abdomen, properly so called, and a limit be- 

 tween it and the pelvis; and this artificial divi- 

 sion of a cavity, naturally single, may be 

 useful in describing the positions of viscera, but 

 to understand the functions of the abdomen, 

 it will be expedient to consider that cavity 

 and the pelvis as one. Some anatomists ob- 

 ject to the use of the term cavity as applied 

 to the abdomen, because no cavity can be said 

 to exist, except in the skeleton or in the evisce- 

 rated subject; neither can there properly be 

 said to be a cavity of the thorax or of the cra- 

 nium, inasmuch as that cavity is obliterated so 

 long as the viscera are in a stale of integrity. 

 I apprehend that the objection is hypercriti- 

 cal, as it must be evident that the cavity does 

 not become apparent till the viscera have been 

 removed; nevertheless, it is perfectly correct 

 to say that it contains the viscera, nor is it in- 

 correct to make use of the expression " anatomy 

 of the abdominal cavity," to imply the anatomy 

 of its contents when in their natural position. 

 Hence, then, we derive a natural subdivision, 

 in treating the subject of this article, into two 

 heads: 1. the anatomy of the walls of the 

 abdomen ; and, 2. the anatomy of the cavity of 

 the abdomen. 



I. Of the walls of the abdomen. One of the 

 most striking differences between the abdomen 

 and the other great visceral cavities consists in 

 the small proportion of bone that exists in its 

 walls. The osseous boundaries of the abdomen 

 maybe thus enumerated: superiorly, towards 

 the posterior and outer part, the false ribs; 

 posteriorly, the lumbar region of the spine, 

 which by its transverse processes affords strong 

 points for the attachment of muscles, and by 

 the bodies projects into the cavity, forming 

 an imperfect septum, slightly convex on its 

 anterior surface, and dividing the cavity into 

 two symmetrical portions. Inferiorly, the alae 

 of the ilia afford lateral expansions, which 

 support some of the contents of the abdo- 

 men, and the pelvic brim completed behind 

 by the promontory of the sacrum, forms the 

 opening by which the cavity of the true pelvis 

 communicates with that of the abdomen. 



Between the inferior margin of the thorax 

 and the superior margin of the false pelvis are 

 stretched muscular lamellae and tendinous ap- 

 oneuroses, the cingulum abdominis musculoso- 

 aponeurotiaim of Albinus and Haller, which, 

 with integument, cellular membrane, &c. form 

 the anterior, lateral, and for the most part 

 the posterior walls of the abdomen, and circum- 

 scribe that space to which we have already 

 alluded under the name of the cavity of the 

 abdomen. 



The superior wall of the abdomen is the 

 diaphragm, and the inferior' wall of the abdo- 

 men, strictly so called, is formed by the ilia 

 and their muscles, and is open in the centre at 

 the superior outlet of the pelvis ; but if the 

 abdominal and pelvic cavities be considered as 

 one, then those parts which fill up the inferior 

 outlet of the latter must be considered as 

 likewise constituting the inferior wall of the 

 former. 



In the male adult the abdomen presents an 

 expanded convex surface anteriorly (the ante- 

 rior wall or proper abdominal region) ; poste- 

 riorly a broad surface not so extensive, situated 

 between the last ribs and the superior margin 

 of the pelvis, and divided into two by the 

 lumbar portion of the spine (the posterior wall, 

 the loins, or lumbar regions.) The anterior 

 and posterior walls are connected with each 

 other on the sides by two narrow regions (the 

 lateral walls or the flanks.) 



The outline of the anterior wall or pro- 

 per abdominal region constitutes an oval, whose 

 long axis is vertical. The surface is generally 

 more or less convex during life, proportionally 

 with the degree of embonpoint of the indivi- 

 dual, and also according to the condition of the 

 diaphragm. After death, excepting in very fat 

 subjects, or where the intestines or peritoneal 

 cavity are much distended from any cause, this 

 surface is in a variable degree collapsed, and 

 more or less concave, but especially so in very 

 thin and emaciated subjects. There is a con- 

 stant adaptation in the condition of this surface 

 to that of the abdominal viscera, so that the 

 practitioner can in general argue pretty accu- 

 rately, from the state of the abdominal surface, 

 respecting that of the abdominal viscera, ex- 

 cept in cases where every thing is masked by a 

 superabundant deposition of adipose substance. 

 So close is the apposition of the abdominal wall 

 to the surfaces of the subjacent viscera, that in 

 some cases of extreme emaciation the peristaltic 

 movement of the intestinal canal is manifested 

 by the successive elevation and depression of 

 small portions of the walls corresponding to the 

 dilated and contracted portions of intestine. 

 This surface is divided into two equal and 

 symmetrical portions by a groove which exists 

 along the middle line, and which is chiefly ap- 

 parent in the two superior thirds. This groove 

 commences below the ensiform cartilage, where 

 there is a slight depression, denominated the 

 scrobiculus cordis, (creux de 1'estomac.) In 

 this line, about midway between the pubis and 

 xiphoid cartilage, is the round depression called 

 the umbilicus or navel. Just over the pubis there 

 is a prominent surface in both sexes covered 



