THE ABDOMEN 



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the anterior superior iliac spine. By means of these imaginary planes the abdomen 

 is divided into three zones, which are named, from above downward, subcostal, 

 umbilical, and hypogastric zones. Each of these is further subdivided by two 

 sagittal planes, which are indicated on the surface by lines drawn vertically through 

 points half way between the anterior superior iliac spines and the symphysis pubis. 

 The regions as outlined by the BNA Commission are shown in Fig. 960. 1 



The middle region of the upper zone is called the epigastric, and the two lateral 

 regions, the right and left hypochondriac. The central region of the middle zone is 

 the umbilical; and the two lateral regions, the right and left lumbar. The middle 

 region of the lower zone is the hypogastric or pubic region; and the lateral regions 

 are the right and left iliac or inguinal. 



REGIO INGUINALIS -. 



R. ABDOMINIS I 



LATERALIS I R.UMBILICALIS I 



FIG. 960. Regions of the abdomen, according to the BNA Commission. 



The pelvic cavity is that part of the abdominal cavity which lies below and behind 

 a plane passing through the promontory of the sacrum, the iliopectineal lines and 

 the pubic crests. It is bounded behind by the sacrum, coccyx, Pyriformis muscles, 

 and the great sacrosciatic ligaments; in front and laterally by the pubes and ischia 

 and Obturator internus muscles; above, it communicates with the cavity of the 

 abdomen; below, it is closed by the Levatores ani and Coccygei muscles and the 

 triangular ligament. The pelvic cavity contains the urinary bladder, the sigmoid 

 colon, the rectum, a few coils of small intestine, and some of the generative organs. 



If the anterior abdominal wall is reflected in the form of four triangular flaps 

 by means of vertical and transverse incisions the former from the ensiform car- 

 tilage to the symphysis pubis, the latter from flank to flank at the level of the 

 umbilicus the abdominal or peritoneal cavity is freely opened and the contained 



1 Anatomists are far from agreed as to the best method of subdividing the abdominal cavity, Addison (Jour- 

 nal of Anatomy and Physiology, vols. xxxiv and xxxv), in a careful analysis of the abdominal viscera in forty 

 subjects, adopts the following lines: (1) a median, from the symphysis pubis to the ensiform cartilage; (2) two 

 lateral lines drawn vertically through a point midway between the anterior superior iliac spine and the symphysis 

 pubis; (3) an upper transverse line half way between the symphysis pubis and the suprasternal notch; and 

 (4) a lower transverse line midway between the last and the upper border of the symphysis pubis. The upper 

 transverse line corresponds with what he has termed the transpyloric plane, from the fact that in most cases 

 this plane traverses the pylorus. 



