THE THIGH 189 



the lumbo -inguinal nerve ; (2) the lateral cutaneous nerve of the 

 thigh ; and (3) the femoral nerve. The lumbo-inguinal nerve 

 descends in the lateral compartment of the femoral sheath 

 on the lateral side of the femoral artery. It pierces the 

 lateral wall of the sheath and the fascia lata a short distance 

 below the inguinal ligament, and has already been traced to 

 its distribution (p. 175). The lateral cutaneous nerve of the 

 thigh passes into the thigh behind the inguinal ligament, close 

 to the anterior superior spine of the ilium. It soon leaves the 

 femoral triangle by crossing the sartorius and piercing the fascia 

 lata. It has already been traced in its ramifications in the 

 superficial fascia on the lateral aspect of the thigh. The 

 femoral nerve will be detected, lying deeply, in the interval 

 between the psoas and iliacus muscles, about a quarter 

 of an inch to the lateral side of the femoral artery. In- 

 sinuate the handle of a knife under the main trunk, so as to 

 raise it above the level of the muscles between which it lies, 

 and render it tense, and then follow the numerous branches 

 into which it breaks up as far as the limits of the space will 

 allow. The small twig to the pectineus muscle must be 

 looked for. It passes medially, posterior to the femoral 

 vessels. 



The floor of the femoral triangle slopes backwards both from 

 the medial and the lateral boundary of the space. To the 

 medial side of the femoral artery it is formed by the adductor 

 longus and the pectineus ; in some cases a small portion of the 

 adductor brevis may be seen in a narrow interval between 

 these two muscles. To the lateral side of the artery are the 

 psoas and iliacus. The adductor longus is placed in an 

 oblique plane, the medial border being nearer the surface than 

 the lateral border ; and thus it is that this muscle not only 

 forms the medial boundary of the triangle, but also takes part 

 in the formation of the floor. These muscles should be 

 cleaned in so far as they stand in relation to the femoral 

 triangle. 



When a transverse section is made through the frozen thigh in the 

 region of the femoral triangle, the space has the appearance of a deep 

 intermuscular furrow, bounded on the medial side by the adductor longus 

 and pectineus, and on the lateral side by the sartorius and rectus femoris, 

 whilst behind it is separated from the bone by the ilio-psoas. The femoral 

 vessels and the femoral nerve pass, distally in this groove the a. profunda 

 femoris being placed very deeply, whilst the femoral artery lies nearer to 

 the surface. 



