The Posterior Limb. 229 



C. Flexor group. The muscles arise from the medial and 

 lateral condyles of tibia and femur (the flexor digitorum sublimis 

 from the posterior surface of the tibia). They lie behind the axis 

 of the tibia, and are inserted, both on the heel and on the plantar 

 surface of the foot. 



(a) The triceps surae comprises: 



(1) The gastrocnemius. Origin: in two portions: 

 Caput laterale: Lateral condyles of tibia and femur and 

 related, femoral sesamoid. 



Caput mediale: Medial condyle of the femur and. its sesa- 

 moid. 



(2) TheSOleus: Origin: By a strong tendon from the 

 head of the fibula. 



Insertion: Through the Achilles' tendon (tendo calcaneus). 

 The latter passes over the posterior end of the tuber cal- 

 canei, and is attached to its ventral surface. The tendon is 



covered by that of the plantaris muscle. 



The small saphenous artery and vein lie at the posterior margin of 

 the lateral head of the gastrocnemius in company with the lesser sap- 

 henous nerve. 



(b) The plantaris. Origin: Lateral condyle of the femur and 

 associated sesamoid. Insertion: The tendon passes over 

 the heel to the plantar surface of the foot, and divides into 

 four parts for insertion on the second phalanges of the four 

 developed digits. 



The two muscles should be divided. 



(c) The popliteus. Origin: Lateral condyle of the femur: 

 The tendon passes through the capsule of the knee-joint. 

 The muscle contains the tibial sesamoid. It crosses the 

 posterior surface of the tibia obliquely, and is inserted on the 

 proximal portion of its posteromedial angle. 



(d) The flexor digitorum longus. Origin: Lateral condyle 

 of the tibia and head of the fibula, extending to the posterior 

 surface of the interosseous ligament and associated, portions 

 of the tibia and fibula. Insertion: The tendon passes 

 beneath the sustentaculum tali, reaching the plantar surface 

 of the foot, where it is partly covered by the plantaris ten- 

 don. It divides into four parts for insertion on the ungual 

 phalanges of the four developed digits. 



