188 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM 



nearly surrounds the abdomen, and is inserted into the anterior 

 aponeurosis and conjoined tendon. This aponeurosis com- 

 mences for the most part about 1 inch from the outer border 

 of the rectus in the linea Spigelii (p. n.), but muscular fibers 

 nearly meet behind the rectus above; the lower third of this 

 aponeurosis passes in front of the rectus. 



The posterior aponeurosis is the middle layer of the lumbar 

 fascia or lumbocostal ligament (Henle), between the erector 

 spime and quadratus lumborum muscles. The highest part 

 of this muscle is continuous with the triangularis sterni. 



Nerves. Supplied in general by the lower intercostal nerve; 

 internal oblique and transversalis, also by the iliohypogastric 

 and the ilioinguinal nerves; the cremaster by the genital branch 

 of the genitocrural nerve. 



Actions. Upon the thorax, viscera, or vertebral column; 

 pelvis and thorax fixed, they aid vomiting, expulsion of fctiitt, 

 feces, and urine; vertebral column fixed, they raise the dia- 

 phragm by pressing up the viscera, and so aid expiration; flex 

 the thorax to the front or laterally, or rotate it if the vertebral 

 column be not fixed; thorax fixed, draw up the pelvis in climb- 

 ing. Pyramidales make the linea alba tense. 



THE LINING FASCLffi OF THE ABDOMEN 



The transversalis fascia covers the inner surface of that 

 muscle, and is continued upon the under surface of the dia- 

 phragm; along the inner margin of the iliac crest it is attached 

 to the periosteum; for about 2 inches internal to the anterior 

 superior iliac spine it is attached to the back of Poupart's 

 ligament and the iliac fascia; next internally it passes down 

 over the femoral vessels as the anterior portion of their sheath; 

 as it passes under Poupart's ligament it is strengthened by 

 the deep crural arch (arcus cruralis), a band of fibers inserted 

 into the pubic spine and iliopectineal line behind the con- 

 joined tendon; it includes beneath it, between the femoral 

 vein and Gimbernat's ligament, the femoral ring, through 

 which a femoral hernia may descend. 



The internal abdominal ring is situated in the transversalis 

 fascia, midway between the spine of the ilium and the crest 

 of the pubic bone. It is \ inch above Poupart's ligament, 

 and is the internal opening of the inguinal canal. It trans- 



