VESSELS IN ABDOMINAL WALL. 419 



raising the outer edge of the rectus, one above and the other below, rami- 

 fying in the muscle. 



The epigastric, with its earliest branches, may be traced by removing 

 the fascia trans versalis from it near Poupart's ligament. The circumflex 

 iliac artery lies behind the outer half of Poupart's ligament, and should 

 be pursued along the iliac crest to its ending. 



Deep crural arch. Below the level of Poupart's ligament is a thin band 

 of transverse fibres over the femoral vessels, which has received the name 

 deep crural arch from its position and resemblance to the superficial crural 

 arch (Poupart's ligament). This fasciculus of fibres, beginning about the 

 centre of the ligament, is prolonged inwards to the pubes, where it is 

 widened, and is inserted into the pectineal line at the deep aspect of the 

 conjoined tendon of the broad muscles of the abdomen. 1 It is closely 

 connected with the front of the crural sheath. 



VESSELS IN THE WALL OF THE ABDOMEN. On the side of the abdomen 

 are the intercostal and lumbar arteries with the intercostal nerves. In the 

 sheath of the rectus lie the epigastric and internal mammary vessels ; and 

 around the crest of the hip-bone bends the circumflex iliac branch. 



The intercostal arteries (fig. 138) issue between the false ribs (p. 337), 

 and enter the abdominal wall between the transversalis and internal ob- 

 lique muscles: they extend forwards with the nerves, supplying the con- 

 tiguous muscles, and some end in the teguments. In front they anasto- 

 mose with the internal mammary and epigastric : behind they communicate 

 with the lumbar arteries. 



The lowest artery accompanies the last intercostal nerve below the last 

 rib, and is distributed with the nerve. 



The internal mammary artery. The abdominal branch of this vessel 

 (p. 239) enters the wall of the abdomen beneath the cartilage of the seventh 

 rib. Descending in the sheath of the rectus, the vessel soon enters the 

 substance of the muscle, and anastomoses in it with the epigastric artery. 

 The epigastric artery (fig. 140, a~) arises from the external iliac about 

 a quarter of an inch above Poupart's ligament ; it ascends in the sheath 

 of the rectus and divides above the umbilicus into branches which enter 

 that muscle, and anastomose with the internal mammary. 



As the artery courses to the rectus it passes beneath the cord, and on 

 the inner side of the internal abdominal ring ; and it is directed obliquely 

 inwards across the lower part of the abdomen, so as to form the outer 

 boundary of a triangular space along the edge of the rectus. It lies at 

 first beneath the fascia transversalis ; but soon perforates the fascia, and 

 enters the sheath of the rectus over the semilunar border at the posterior 

 aspect. 



The branches of the artery are numerous, but inconsiderable in size : 

 a. The pubic branch is a small transverse artery, which runs behind 

 Poupart's ligament to the posterior aspect of the pubes, and anastomoses 

 with a similar branch from the opposite side. Behind the pubes it com- 

 municates with a small offset from the obturator artery (fig. 141,/) : the 

 size of this anastomosis varies much, but its situation is internal to the 

 crural ring. 



1 Sometimes this structure is a firm distinct band, which is joined by some of 

 the lower fibres of the aponeurosis of the external oblique. At other times, and 

 this is the most common arrangement, it is only a thickening of the fascia trans- 

 versalis with the fibres added from the tendon of the transversalis muscle. 



