616 THE BLOOD-VASCULAR SYSTEM 



artery only courses around the medial side of the ring — in which situation it is liable to injury 

 in the operation for femoral hernia — in exceptional cases. According to Langton (Holden's 

 'Anatomy'), the chances are about seventy to one against this occurring. But even when it 

 takes the abnormal course, it hes 3 mm. or so from the margin of the ring, and will probably 

 escape injury in the division of the stricture if several short notches are made in place of a single 

 and longer incision. 



(2) The Deep Circumflex Iliac Artery 



The deep circumflex iliac artery [a. circumflexa ilium profunda], arises from 

 the lateral side of the external iliac artery either opposite the epigastric or a little 

 below the origin of that vessel. It courses laterally just above the lower margin 

 of Poupart's ligament, lying between the fascia transversalis and the peritoneum, 

 or at times in a fibrous canal formed by the union of the fascia transversalis with 

 the iliac fascia. Near the anterior superior spine of the ilium, it perforates the 

 transversus, and then courses between that muscle and the internal oblique, 

 along and a little above the crest of the ilium. It finally gives off an ascending 

 branch, which anastomoses with the lumbar and lower intercostal arteries, and 

 runs backward to anastomose with the ilio-lumbar artery. It is accompanied by 

 two veins. These unite into one trunk, which then crosses the external iliac artery 

 to join the external iliac vein. 



The branches of the deep circumflex iliac artery are as follows: — (a) Muscular branches 

 which supply the psoas, iliacus, sartorius, tensor fascise latse, and the oblique and transverse 

 muscles of the abdomen. One of these branches, larger than the rest, usually arises about 

 2.5 cm. (1 in.) behind the anterior superior spine of the ilium and ascends perpendicularly be- 

 tween the transversus muscle and the internal oblique. It has received no name but is impor- 

 tant to the surgeon, as it indicates the intermuscular plane between the two muscles. (6) 

 Cutaneous branches, which supply the skin over the course of the vessel, and anastomose 

 with the superficial circumflex iliac, the superior gluteal, and the ascending branch of the lateral 

 circumflex. 



THE FEMORAL ARTERY 



The femoral artery (fig. 496) is the continuation of the external iliac, and 

 extends from the lower border of Poupart's ligament, down the anterior and 

 medial aspect of the thigh, to the tendinous opening in the adductor magnus, 

 through which it passes into the popliteal space, and is then known as the pop- 

 liteal. The femoral artery is at first quite superficial, being merely covered by the 

 skin, and superficial and deep fascia; but, after thus passing about 13 cm. (5 in.) 

 downward through the space known as the femoral trigone (Scarpa's triangle), 

 it sinks at the apex of that triangle beneath the sartorius muscle, and thence 

 to its termination continues beneath the sartorius, coursing deeply between the 

 vastus medialis and adductor muscles in the space known as the adductor 

 (Hunter's) canal. It at first rests upon the brim of the pelvis and head of the 

 thigh bone, from which it is merely separated by the capsule of the hip-joint and 

 the tendon of the psoas. Here it can be readily compressed. Owing to the 

 obliquity of the neck of the femur and the direct course taken by the artery, it 

 lies lower down on muscles only, at some little distance from the bone. At its 

 termination, in consequence of the shaft of the femur inclining toward the middle 

 line of the body, the artery lies close to the bone, but to the medial side. The 

 course of the vessel when the thigh is slightly flexed and abducted— the position 

 in which the limb is placed when the vessel is ligatured — is indicated by a line 

 drawn from a spot midway between the anterior superior spine of the ilium and 

 the symphysis pubis to the adductor tubercle. When the thigh is in the extended 

 position and parallel to its fellow, the course of the artery will correspond to a line 

 drawn from the spot aljove mentioned to the medial border of the patella. 



About 4-5 cm. (1^-2 in.) below the inguinal ligament the femoral artery gives 

 off a larg(! branch called tlie profunda femoris. The portion of tiie artery proximal 

 to the origin of tin; profunda is sometimes called the common femoral, and the 

 continuation of tii(! vessel the superficial femoral. 



The superficial femoral varies in length according to the distance that the profimda is given 

 ofT from the common femoral below I'oupnrt's ligament. As a rule, it measures 9 cm. (3| in.), 

 the common 4 cm. (1^ in.). But the profunda may come off 5 cm. (2 in.) or more below Pou- 

 part's ligament, in which case the superficial femoral will be shorter to this extent; or it may 



