FASCIJE 



479 



20"^ 19 



I The semimembranosus has a special fascial investment which, on the back of the knee 

 becomes bound on each side of the muscle and its tendon to the capsule of the joint. This 

 fascia extends into a transverse septal membrane which is continued over the deep muscles of 

 the back of the leg to the ankle. It is united on one side to the tibia, on the other to the fibula. 

 Proximally the fibres are continued into it from the tendon of the semimembranosus. Over 

 the back of the tibia the septum is interrupted by the attachment of the soleus to the pophteal 

 fine. Beyond the tibial origin of the soleus it is fused on the medial side of the flexor digitorum 

 longus to the crural fascia. 



In addition to the two intermuscular septa and the longitudinal transverse septum, other 

 septa serve to separate the individual muscles of the different groups. 



Above the ankle the fascia is enforced by bands of tissue so that ligaments are formed 

 which serve to retain in position the various tendons which pass from the leg into the foot. 



The transverse crural ligament (upper part of anterior annular ligament) (fig. 415) lies 

 on the front of the lower part of the leg above the ankle. It is composed of fascia strengthened 

 by transverse bundles which pass from the medial side of the tibia to the veritral margin of the 

 fibula. From its deep surface a strong, broad septum descends to the tibia and divides the 

 underlying space into two osteo-fibrous canals, a medial for the tibialis anterior and a lateral 

 for the long extensor muscles. The lateral compartment is further subdivided by a shghtly 

 marked septum into a medial division for the extensor hallucis longus and a lateral for the ex- 

 tensor digitorum longus and the peroneus tertius. 



The cruciate ligament (lower part of anterior annular hgament) (fig. 415) serves to hold 

 the tendons of the anterior muscle group in place as they pass to the dorsum of the foot. In 

 part it is formed by a dense fibrous band lying in the fascia over the ankle, in part of a liga- 

 ment which passes from the bones of the ankle to the deep surface of this band. The superficial 

 band is V-shaped. It arises from the lateral surface of the body of the calcaneus and passes 

 across the dorsum of the foot, one arm of the V going to the medial malleolus, the other to the 

 side of the foot, where it terminates in the fascia over the first cuneiform bone. The apex of 

 the V lies over the tendons of the extensor digitorum longus and peroneus tertius muscles. 

 The distal arm extends over the tendons of the extensor hallucis longus and tibiahs anterior 



