THE ABDOMINAL WALLS 253 



(a) SUPERFICIAL. The arteries which supply the lower 

 part of the wall are all derived from the femoral, and ascend 

 from the thigh, (i) The Superficial Epigastric crosses the 

 middle of the inguinal ligament. (2) The Superficial External 

 Pudendal runs medially across the spermatic cord. Both of 

 these vessels are usually divided in the incisions for inguinal 

 hernia. (3) The Superficial Circumflex Iliac supplies the 

 skin in the neighbourhood of the anterior superior iliac spine. 



(b) DEEP. i. The Inferior (Deep) Epigastric artery arises 

 from the external iliac, just above the inguinal ligament, and 

 ascends in the direction of the umbilicus. At first it lies in the 

 extra-peritoneal fat, but it soon pierces the fascia transversalis, 

 and enters the rectus sheath by passing in front of the linea 

 semicircularis (semilunar fold of Douglas). It then runs 

 upwards on the deep surface of the rectus and anastomoses 

 with the superior epigastric, which is descending from the 

 internal mammary. 



The inferior epigastric artery may be injured if the oblique 

 appendicular wound (p. 248) is increased downwards and 

 medially, or when the rectus is split longitudinally. 



The origin of the inferior epigastric lies half an inch above 

 the inguinal ligament, and midway between the anterior superior 

 iliac spine and the symphysis pubis. Its course may be indicated 

 by a line drawn from its point of origin towards the umbilicus. 



The important relations of this vessel to the inguinal canal 

 and to the varieties of inguinal hernia are described on pp. 255 

 and 263. 



2. The Deep Circumflex Iliac artery also arises from the 

 external iliac, just above the inguinal ligament. It passes 

 upwards and laterally along the inguinal ligament and the 

 iliac crest. Just behind the anterior superior spine it gives off 

 a moderately large branch, which ascends between the internal 

 oblique and transversus, and may be injured when the gridiron 

 appendicular incision is prolonged laterally. 



The Inguinal Region. The Inguinal Canal is an oblique 

 cleft in the anterior abdominal wall above the medial half of 

 the inguinal ligament. In the male it contains the spermatic 

 cord, and this structure enters the canal at its upper end through 

 the Abdominal Inguinal (Int. Abd.) Ring, which is situated in 

 the fascia transversalis about half an inch above the inguinal 

 ligament, midway between the anterior superior iliac spine and 

 the pubic symphysis. The canal is about one and a half inches 



