INTERNAL OBLIQUE MUSCLE. 



251 



inner border, so as to enclose it in a sheath. The anterior layer, as already 

 mentioned, becomes inseparably united with the aponeurosis of the external 

 oblique muscle, and the posterior layer is similarly incorporated with that 

 of the transversalis. The upper border of the posterior lamina is attached 

 to the margins of the seventh and eighth ribs, as well as to the ensiform 

 cartilage. This division, however, of the aponeurosis into layers stops 

 short a little above the middle distance between the umbilicus and the 

 pubes, the aponeurosis below that level remaining undivided, and along with 



Fig. 198. 



Fig. 198. LATERAL VIEW OF THE 

 MUSCLES OP THE ABDOMEN AND 

 TRUNK, THE INTERNAL OBLIQUE 

 MUSCLE HAVING BEEN EXPOSED 

 BY THE REMOVAL OP THE EXTERNAL 

 OBLIQUE (modified from Henle). 



a, anterior superior spinous process 

 of the ilium ; 6, trochanter major ; 

 c, spine of pubes ; d, lumbar fascia ; 

 VI to XII, the sixth to tbe twelfth 

 ribs ; 1, lower part of the great pec- 

 toral muscle, where it is attached to 

 the external oblique muscle ; 2, 2, 

 lower digitations of the serratus mag- 

 nus from the fourth to the eighth ribs ; 

 3, lower costal attachments of the 

 latissimus dorsi ; 3', its iliac attach- 

 ment ; 4, trapezius ; 5, divided attach- 

 ments of the external oblique, left in 

 connection with the ribs ; 5', aponeu- 

 rosis of tbe external oblique divided in 

 front of the rectus, where it joins the 

 sheath ; 6, internal oblique at its 

 middle ; 6', 6', line where it divides 

 to form the sheath of the rectos ; 

 + + + XII, its attachments to the 

 four lowest ribs ; 6", the conjoined 

 tendon, and above, and to the out- 

 side, the internal inguinal aperture ; 

 7, sartorius ; 8, rectus femoris ; 9, 

 tensor vaginae femoris ; 10, gluteus 

 medius ; 11, gluteus maximus. 



that of the transversalis muscle to 

 which it is united, passing wholly 

 in front of the rectus muscle. The 

 deficiency thus resulting in the 

 posterior wall of the sheath of 

 the rectus muscle is marked 

 superiorly by a well-defined lu- 

 nated edge, whose concavity 

 looks downwards towards the 

 pubes the semilunar fold of 

 Douglas. 



The internal oblique muscle is 

 almost entirely covered by the ex- 

 ternal oblique. A small angular portion only near the place where its posterior fibres 

 take their origin, under cover of the latissimus dorsi, is exposed between that muscle 

 and the external oblique, and even this is not constantly found. 



The cremaster, a muscle peculiar to the male, consists of fibres lying in 



