chap, xvi.] THE ABDOMINAL PARIETES. 289 



a male, by invaginating the scrotum so as to pass the 

 finger beneath the subcutaneous fat. In the female the 

 position of the process may be made out by adducting 

 the thigh and thus making prominent the tendon of 

 origin of the adductor longus muscle. This muscle 

 arises from the body of the pubes immediately below 

 the spine, and by running the finger along the muscle 

 the bony prominence may be reached. If the finger be 

 placed upon the pubic spine it may be said that a 

 hernia descending to the inner side of the finger will 

 be inguinal, while one presenting to the outer side 

 will be femoral. In the erect position of the body the 

 anterior superior spine is a little above the level of the 

 promontory of the sacrum, while the tip of the xiphoid 

 cartilage corresponds to about the lower part of the 

 tenth dorsal vertebra. 



In that part of the back which corresponds to 

 the abdominal region the erector spinae masses are 

 distinct, and in any but fat subjects their outer 

 edges can be well defined. Between these masses 

 is the spinal furrow, which ends below in an angle 

 formed by the two great gluteal muscles. Immediately 

 above the middle of the crest of the ilium is Petit's 

 triangle, or the gap between the external oblique and 

 latissimus dorsi muscles. The fourth lumbar spine 

 is about on a level with the highest part of the iliac 

 crest In counting the ribs it is well to commence 

 from above, since the last rib may not project beyond 

 the outer edge of the erector spinae, and may conse- 

 quently be overlooked. 



The aorta bifurcates opposite the middle of the 

 body of the fourth lumbar vertebra just to the left of 

 the middle line. This spot corresponds very nearly to 

 the highest point of the iliac crest, and will therefore 

 be situate about three-quarters of an inch below and to 

 the left of the umbilicus. A line drawn on either side 

 from the point of bifurcation to the middle of Pou part's 



T 4 



