THE FASCIA AND MUSCLES OF THE ABDOMEN 187 



a triangular space between them on the iliac crest, forming 

 Petit's triangle. Thirty or forty cases of lumbar hernia pro- 

 truding through this space have been recorded. 



2. M. Obliquus Internus. Origin, outer half of Poupart's 

 ligament, anterior two-thirds of the middle ridge of the iliac 

 crest, from the lumbar fascia; insertion, lower margins of the 

 cartilages of the last three ribs, its aponeurosis, and by con- 

 joined tendon (with transversalis) arching over the inguinal 

 canal to the front of the pubis and inner part of the iliopec- 

 tineal line behind Gimbernat's ligament. Sometimes the con- 

 joined tendon divides into an outer portion, the ligament of 

 Hesselbach; and an internal portion, the ligament of Henle. The 

 aponeurosis splits at the outer border of the rectus; the anterior 

 layer unites with the external oblique aponeurosis, the posterior 

 with the transversalis aponeurosis, which reunite and form 

 the sheath of the rectus; the posterior layer is attached above 

 to the ensiform, seventh and eighth rib cartilages. This divi- 

 sion of aponeurosis stops a little above half-way between the 

 umbilicus and pubis, and below this point the internal oblique 

 aponeurosis and transversalis aponeurosis pass wholly in front 

 of the rectus. This deficiency in the posterior wall of the 

 sheath is marked by a lunated edge, concave downward, the 

 semilunar fold of Douglas (linea Douglasii, p. n.); here the 

 rectus is separated from the abdominal contents by perito- 

 neum, subperitoneal tissue, transversalis fascia, and a thin 

 connective tissue which continues the transverse aponeurosis. 

 (Note a difference between the transversalis fascia and the 

 aponeurosis.) 



The cremaster muscle, peculiar to the male, is attached 

 externally to the inner portion of Poupart's ligament, and is 

 continuous with the internal oblique fibers; its internal attach- 

 ment (inconstant) is the spine and crest of the pubis; it descends 

 in folds in front of the spermatic cord to the level of the testis, 

 and spreads out in a cremasteric fascia. Some regard this 

 muscle as a part of a fetal structure called gubernaculum testis. 

 There are some remains of it in the female. 



3. M. Transversalis Abdominis. Origin, inner surface of 

 the lower six rib cartilages, interdigitating with the diaphragm, 

 from the lumbar transverse process by a posterior aponeurosis, 

 from the anterior three-fourths of the inner margin of the 

 iliac crest, outer third of Poupart's ligament. This muscle 



