THE ABDOMINAL WALL 249 



the penis six arteries may be met with. They are the two 

 dorsal arteries, the two profunda arteries, and the two arteries 

 to the bulb of the penis. 



TRIGONUM LUMBALE AND LUMBAR FASCIA. 



On the sixth day after the body was placed on its back 

 it will be turned upon its face, with blocks supporting the 

 thorax and pelvis, and in that position it will remain for five 

 days. At the end of the first or the beginning of the second 

 day of the period, after the dissector of the upper extremity 

 has cleaned the latissimus dorsi, the dissector of the 

 abdomen must take the opportunity of examining the 

 posterior border of the external oblique. As the posterior 

 border of the muscle passes from the last rib to the external 

 lip of the iliac crest it is quite free, and, in many cases, 

 there is a small triangular interval between it and the lower 

 part of the lateral border of the latissimus dorsi in which the 

 fibres of the more deeply situated internal oblique can be 

 seen. The triangle is the trigonum lumbale (Petiti). It is a 

 comparatively weak region of the abdominal wall, and in 

 some rare cases hernia of the abdominal contents occurs 

 through it. Not uncommonly, however, the lateral border 

 of the latissimus dorsi overlaps the posterior border of the 

 external oblique, and in those cases the trigonum lumbale 

 does not exist. 



On the third day, after the dissector of the upper extremity 

 has reflected the muscles which connect the upper extremity 

 with the trunk on the posterior aspect, the dissector of the 

 abdomen, in association with the dissector of the head and 

 neck, should examine the lumbar fascia and the lumbar 

 origins of the internal oblique and the transversus abdominis 

 muscles. 



The lumbar fascia is a portion of the lumbo-dorsal fascia 

 which binds down the deep muscles of the back at the sides 

 of the spines of the vertebrae. In the thoracic region it is a 

 thin transparent lamina which extends from the spines of 

 the vertebrae to the angles of the ribs. At the upper end of 

 the thoracic region it disappears into the neck under cover 

 of the serratus posterior superior. In the lumbar region it 

 becomes much stronger and more complicated. Above, it is 

 continuous with the thoracic portion of the fascia and is 



