174 INFERIOR EXTREMITY 



Dissection. Clean the great saphenous vein proximo-distally, taking care 

 to avoid injuring any of the branches of the cutaneous nerves which lie 

 close to it. In the proximal part of the thigh it is accompanied by 

 branches of the medial cutaneous nerve (O.T. internal cutaneous), one 

 of the anterior cutaneous branches of the femoral nerve. In the distal 

 part of the thigh it is accompanied by the anterior branch of the same 

 nerve and it passes across the medial and posterior aspect of the knee, where 

 it is accompanied by the saphenous nerve. Clean also the tributaries of 

 the vein and avoid injury to the cutaneous nerves which they cross. 



Vena Saphena Magna (O.T. Internal Saphenous Vein). 

 This is the largest superficial vein of the inferior extremity. 

 It commences on the dorsum of the foot, passes proximally 

 anterior to the medial malleolus and across the medial 

 surface of the distal third of the tibia, and then along the 

 medial margin of the tibia. It enters the area of dissection 

 at present under consideration at the level of the tuberosity of 

 the tibia, passes proximally across the posterior part of the 

 medial aspect of the knee, then further proximally, with an 

 inclination anteriorly and laterally, through the medial region 

 of the thigh to the fossa ovalis, where it pierces the fascia 

 cribrosa and the femoral sheath and terminates in the 

 femoral vein. In its course through the thigh it receives 

 tributaries from the anterior and medial regions, the former 

 constitute the lateral femoral circumflex veins and the latter 

 the medial femoral circumflex veins ; one of the latter not 

 uncommonly connects the great saphenous veins with the 

 small saphenous vein. Just before it pierces the fascia 

 cribrosa the great saphenous vein is joined by the small veins 

 which correspond with the three superficial arteries of the 

 subinguinal region. 



Nervi Cutanei (Cutaneous Nerves). The cutaneous nerves 

 are now to be looked for in the superficial fascia. The 

 main stems are six in number, and are derived from two 

 sources. Three come directly from the lumbar plexus, and 

 three are branches of the femoral nerve : 



( Ilio-inguinalis. 

 From lumbar plexus, \ Lumboinguinalis. 



( Lateral cutaneous of the thigh. 



{Intermediate cutaneous. 

 Medial cutaneous. 

 Saphenous. 



N. Ilio-inguinalis. The ilio-inguinal nerve will be found 

 as it escapes from the subcutaneous inguinal ring (O.T. ext. 

 abdominal) in company with the spermatic cord. Its branches 



