THE POSTERIOR LIMB 283 



includes the typical extensors and flexors of the foot, together 

 with the peronaei muscles, which individually are extensors and 

 flexors, but collectively have the relation of lateral tractors 

 (Fig. 105). 



A. Extensor group. Muscles occupying an anterior position 

 on the leg and inserted on the dorsum of the foot. 



(a) The extensor hallucis longus. Origin : The medial condyle of 

 the tibia just behind the tibial collateral ligament (p. 290) 

 and the anteromedial surface of the same bone from about the 

 level of the distal end of the tibial tuberosity to the middle of 

 the length of the bone. Also the proximal half of the middle 

 third of the posteromedial border of the tibia. Insertion: 

 The tendon passes round the medial malleolus of the tibia, 

 beneath the base and along the medial surface of the second 

 (first functional) metatarsal, and to the dorsal surface of 

 the basal phalanx of the corresponding digit, where it 

 unites with the first tendon of the extensor digitorum 

 longus. 



This muscle is also identified as a tibialis posterior with 

 displaced insertion tendon and is grouped with the flexors. 



The posterior tibial artery, the continuation of the great saphen- 

 ous, and the tibial nerve accompany the tendon in the malleolar groove. 



(b) The tibialis anterior. Origin: Lateral condyle of the tibia 

 and corresponding surface of the tibial tuberosity. In- 

 sertion: Base of the second metatarsal. The tendon passes 

 beneath the obliquely placed crural ligament of the lower 

 portion of the leg. 



The muscle should be divided and its head reflected. 



(c) The extensor digitorum longus. Origin: By a flattened 

 tendon from the lateral portion of the patellar surface of 

 the femur. This tendon passes through the capsule of the 

 knee-joint, and the fleshy portion of the muscle lies on the 

 anterolateral surface of the tibia. Insertion: The distal 

 tendon passes beneath the crural ligament, then beneath 

 the cruciate ligament of the dorsum of the foot, dividing 

 into four portions for insertion on all the phalanges of the 

 digits. 



