266 - SURGICAL ANATOMY OP 



anterior and a posterior, limited by the inner border of 

 the tibia internally and the outer border of the fibula 

 externally. 



Anterior Region. The skin is freely movable over 

 the subjacent tissues, and in the subcutaneous cellular 

 tissue and fat lie the internal saphena vein, which cross- 

 ing the inner malleolus, passes upwards toward the pos- 

 terior border of the inner condyle of the femur, and is 

 accompanied by the internal saphena nerve. The aponeu- 

 rosis is the continuation downwards of the fascia lata, 

 strengthened superiorly and internally by the expansion 

 of the sartorius tendon, and thickened inferiorly where 

 it forms the annular ligament of the ankle. It is ad- 

 herent to the anterior surface of the tibia and external 

 border of the fibula, and sends septa between and gives 

 attachment to the anterior muscles of the limb ; it is per- 

 forated in several places for the passage of the cutaneous 

 nerves. Inclosed in the space between the aponeurosis 

 superiorly and the tibia, fibula, and interosseous mem- 

 brane posteriorly, lie in the first layer of muscles, the 

 tibialis anticus and the extensor com munis digitorum, 

 united superiorly by an intermuscular septum lower 

 down. They separate and inclose the origin of the ex- 

 tensor proprius pollicis, external to and below which is 

 the peroneus tertius. The space between these muscles 

 and the interosseous membrane is occupied by the an- 

 terior tibial vessels and nerve ; the nerve pursuing the 

 same course as the artery lies at first external to, then 

 upon, and then again outside the vessels. 



External Region. The aponeurosis forms an invest- 

 ment for the peronei muscles ; the compartment corre- 

 sponding to the external surface of the fibula. To the 

 upper and middle thirds of this surface the peroneus 



