V///: ABDOMINAL r.ivm: 381 



t' determine the various regions into which it is p.rv>il>lr to divide it: 

 a matter of some importance, as it singularly fa-ilit:il > the topo graphical 

 study of the contained viscera : for to say that an organ is situated in 

 the ahdomrii. is a very vagu 06 to its precise situation, in conse- 



quence of the great extent of this cavity. It is necessary, therefore, t" 

 divide the abdomen into a certain number of peripheral regions which corre- 

 spond t > the different parts of its wall, with a view to define the situation 

 of the organs lodged therein, yet without complicating anatomical de- 

 scription. Six principal regions are recognised in the abdominal cavity. 



A. The superior, or snblumbar region, corresponds to the superior wall of 

 the alxlomen: that is, to the psoas muscles and the bodies of the lumbar 



!>ne. It extends from the opening between the two pillars of the 

 diaphragm to tin; entrance to the pelvis. 



\\. The Inferior region, limited, laterally, by the hypochondriacs and 

 the flanks, commences, in front, at the xiphoid cartilage, and is prolonged 

 to the pubis ; it comprises all that portion of the abdomen which corrc- 



!s to the linea alba and the two recti muscles. Its great extent 



-sitates its subdivision into five secondary regions : The suprasternal 

 rrgiun, named the epigastric in Man, placed above the xiphoid cartilage of the 



urn ; the umbilical region, situated behind the preceding, and so named 



in consequence of its including that part of the wall which is pierced by the 



umbilicus ; the prepnltic region the hypogastric or pubic of Man occupies 



-pace in front of the anterior border of the pubis; the two injuinnl 



<x, diverticuli of the abdominal cavity, located in the inguinal tracts, 

 where they form the special reservoirs to be hereafter described as the 

 '(/ sheaths (or canals). 



C. The lateral regions (right and left lumbar of Man) are limited : in front, 

 by the costal attachments of the diaphragm ; behind, by the entrance to the 

 pi -1 vie cavity; above, by the superior border of the small oblique muscle; 

 below, l>y the interval comprised between the inferior border of that muscle 

 and the external border of the great rectus muscle. The designation of 



'ninlriii,' is given to the subregion which corresponds to the cartila- 

 .s circle of the false ribs. The flank is that section covered by the 

 muscular portion of the small oblique muscle. 



D. The anterior, or diaphragmatic rnjion, comprises the cavity formed by 

 the posterior face of the diaphragm. Like that muscle, it is divided into 

 two regions, a < iifnil and jn-ripheral. 



E. The posterior, or j Id- region, is a special diverticulum of the abdomen 



: ibed as the pelvic catity. It is bounded, above, by the sacrum ; below, 

 by the sujKjrior face of the pubes, the ischia, and the internal obturator 

 muscle; on the sides, by the constricted portions of the ossa innominate 

 and the sacro-ischiatic ligaments. The entrance to this diverticulum is 

 situated above the pubes, aud is of an oval form. Posteriorly, it is narrower. 

 and is traversed by the rectum aud the genito-nriuary organs, which op n 

 externally. 



THE PERITONEUM. The abdominal cavity is covered, internally, by a 

 serous membrane, the peritoneum, which will now be briefly described. 



Like all the splanchnic serous membranes, the peritoneum is composed of 

 a parietal and a visceral layer, which together form a closed sac so arranged 

 that the organs contained in the abdomen arc situated external to tlii 

 The adjoining theoretical figure (180), representing a transverse section of the 

 abdominal cavity, will show at a glance this arrangement. Let A represent 

 the section of the small intestines floating at liberty in the interior of the 



