DISSECTING MANUAL. 



Rectus Abdominis. Origin; pubic symphysis and crest, by 

 two heads, inner and outer. Insertion ; front of ensiform car- 

 tilage; fifth to seventh costal cartilages. On its anterior sur- 

 face there are three or more transverse tendinous intersec- 

 tions (linece transversal) which adhere to its sheath; the lowest 

 lies opposite the umbilicus and the highest about the level of 

 the costal arch. The convex outer border of the muscle forms 

 the linea semilunaris. [432] 



Sheath of Rectus. This is derived from the aponeuroses of 

 the lateral abdominal muscles. In the upper three-fourths of 

 the abdominal wall the aponeurosis of the Internal oblique 

 splits at the linea semilunaris; the anterior layer, joined by 

 the External oblique aponeurosis, passes in front of the Rectus 

 as the anterior lamina of the sheath; the posterior layer, 

 joined by the Trans versalis aponeurosis, passes behind the 

 Rectus as the posterior lamina. In the lower fourth the apo- 

 neuroses pass in front of the Rectus, so that the sheath is defi- 

 cient behind and the posterior lamina ends inferiorly in a 

 crescentic border (fold of Douglas). Internally all the apo- 

 neuroses interlace with those of the opposite side in a broad 

 band (linea alba} attached to the ensiform cartilage and pubic 

 symphysis. [432] 



Inguinal Canal. This begins at the internal abdominal ring, 

 an orifice lying in the transversalis fascia half an inch above 

 Poupart's ligament and midway between the pubic symphysis 

 and anterior superior iliac spine. It runs obliquely through 

 the abdominal wall and ends at the external ring, which lies 

 above the pubic spine and crest. Front wall; aponeurosis of 

 External oblique; (outer part) Internal oblique. Back wall; 

 transversalis fascia; (inner part) conjoint tendon. Floor; 

 Poupart's ligament ; (inner part) Gimbernat's ligament. The 

 spermatic cord, in traversing it, receives three investments; the 

 first (infundibuliform fascia) of transversalis fascia from the 

 margin of the internal ring; the second (cremasteric fascia) 

 from the lower border of the Internal oblique; and the third, 



[192] 



