THE ABDOMINAL WALL. I2 j 



it is also inserted into the cartilages of the eighth, ninth, and tenth ribs. ED.]. The most internal 

 muscle is the transfer sails, which takes origin from the inner surfaces of the six lower costal 

 cartilages, from the deep layer of the lumbar fascia, from the inner lip of the iliac crest, and from 

 Poupart's ligament, and inserts into the linea alba. The aponeurosis of the external oblique 

 passes only into the anterior layer of the sheath of the rectus; that of the internal oblique runs 

 in both layers of the sheath, and the aponeurosis of the transversalis muscle is found in the pos- 

 terior portion of the sheath above the semilunar line of Douglas and in the anterior portion below 

 it. Posteriorly alongside of the vertebral column in the lumbar region is the quadratus lumborum 

 muscle, which extends between the transverse processes of the lumbar vertebras, the last rib, and 

 the posterior portion of the iliac crest. This muscle holds a most important relation to the kidney 

 (see page 139). The fascia of Retzius varies considerably in different individuals; it seems to 

 form a feeble continuation of the posterior layer of the sheath of the rectus. Behind this fascia, 

 between the transversalis muscle and the peritoneum, is the transversalis jascia, which passes 

 upward to the inferior surface of the diaphragm. It is thin above the umbilicus and in the umbil- 

 ical region, but becomes thicker in the inguinal region and is attached to the internal lip of the 

 iliac crest and to Poupart's ligament. Just above the umbilicus, the transversalis fascia is known 

 as the umbilical fascia but this latter structure is subject to great variation and has received 

 more attention than it deserves from a practical standpoint. 



The arteries of the abdominal wall are to be differentiated as the superficial and the deep. 



The superficial vessels arise from the femoral artery. They are the superficial epigastric 

 and the superficial circumflex iliac (Fig. 77). The superficial epigastric artery is not a partic- 

 ularly large vessel; it perforates the fascia lata below Poupart's ligament and passes upward 

 over this ligament toward the navel, although it does not run as far as the latter structure. The 

 superficial circumflex iliac also perforates the fascia lata and runs parallel to Poupart's ligament 

 to the skin in the region of the anterior superior spine of the ilium. Both arteries are of practical 

 importance, since they supply the so-called inguinal glands. 



The deep arteries are much larger. They are: 



1. The seven lowermost intercostal arteries which run beyond the costal margin and end in 

 the abdominal muscles. 



2. The inferior or deep epigastric artery (Figs. 56 and 71), practically the most important 

 vessel in the anterior abdominal wall, arises from the external iliac just before it passes beneath 

 Poupart's ligament. It runs upward in a curved direction, the concavity being directed outward, 

 passing to the inner side of the internal abdominal ring; the vessel is situated just beneath the 

 peritoneum forming the plica epigastrica (see page 123 and Figs. 56 and 58). At the fold of 

 Douglas it enters the sheath of the rectus and anastomoses freely above the umbilicus with the 

 superior epigastric artery (see page 94). If the circulation in the descending aorta is obstructed, 

 these anastomoses may become dilated and form a collateral path, through which the blood from 

 the subclavian artery may pass along the inner surface of the thoracic and abdominal walls to 

 reach the lower extremity. The course of the inferior epigastric artery corresponds to a line 

 drawn from the junction of the inner and middle thirds of Poupart's ligament to a point one inch 

 to the outer side of the navel. To avoid the artery in tapping for ascites or in other operative 

 procedures the puncture should be made either to the outer side of the vessel at Monro's point 



