4 o6 THE INFERIOR EXTREMITY 



The Femoral Trigone (of Scarpa) is a triangular space lying immediately 

 distal to the inguinal ligament, which forms its base. Its oblique lateral 

 boundary, formed by the sartorius, and its straight medial boundary, formed 

 by the medial border of the adductor longus, meet one another at the apex 

 of the triangle. 



The floor of the space is formed, in its lateral part, by the iliacus and 

 psoas major, as they cross the front of the hip- joint to reach the lesser tro- 

 chanter. The medial part of the floor is formed by the pectineus proximally 

 and the adductor longus distally (Fig. 121). 



The most important contents of the space are the femoral vessels and 

 nerve, together with their large branches. 



The Femoral (Anterior Crural) Nerve (L. 2, 3, 4) 

 enters the thigh by passing behind the inguinal ligament half 

 an inch lateral to the femoral artery. In the pelvis the nerve 

 lies deep to the fascia iliaca. In the thigh it lies in the groove 

 between the psoas major and the iliacus, and is covered over by 

 the fascia lata, which is usually thickened in this situation. 

 The nerve at once breaks up into (i) cutaneous, (2) muscular, 

 and (3) articular branches. 



(1) The medial and intermediate cutaneous nerves are de- 

 scribed on p. 400. 



The saphenous nerve (L. 3 and 4) runs medially and distally 

 towards the femoral artery, and at the apex of the femoral 

 trigone it enters the adductor canal (of Hunter). It leaves the 

 canal at its distal end and pierces the deep fascia near the 

 adductor tubercle, where it becomes associated with the great 

 saphenous vein. Its terminal branches are distributed to the 

 medial side of the leg and foot (p. 499). 



(2) The muscular branches of the femoral nerve supply the 

 pectineus, the sartorius, and the quadriceps extensor. 



(3) Articular branches arise from the nerves to the vasti 

 and supply the knee-joint, while the nerve to the rectus femoris 

 gives off a branch to the hip-joint. In addition to receiving 

 branches from the femoral nerve, both joints are supplied by 

 the obturator nerve (p. 411). It is not uncommon to find that, 

 in tuberculous disease of the hip-joint, the pain is entirely re- 

 ferred to the knee. Whether the pain is referred to the joint or 

 to the overlying skin, which is also supplied by branches of the 

 femoral nerve, is by no means certain. 



The Femoral Artery is the direct continuation of the 

 external iliac. It enters the thigh behind the inguinal ligament 

 at a point midway between the symphysis pubis and the anterior 

 superior iliac spine ; and its course is represented by the proximal 

 two-thirds of the line joining this point to the adductor tubercle, 



