The Posterior Limb. 153 



(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 tendon. It divides 

 into four parts for insertion on the ungual phalanges of the 

 four developed digits. 



The tibial nerve lies on the medial surface of the head of the plantaris 

 and afterwards on the medial surfaces of the popliteus and flexor 

 digitorum longus. 



5. Muscles arising from the foot and inserted on the individual digits. 



(a) The lumbricales. Origin: Tendon of the flexor digitorum 

 longus. Insertion: Medial surfaces of the first phalanges 

 of the three lateral digits. 



(b) The interossei (metatarsi). Origin: From the dorsal portion 

 of the tendon-sheath of the flexor digitorum longus. In- 

 sertion : Heads of the four metatarsals. 



Vessels and Nerves of the Leg and Foot. 



-'=The great saphenous artery passes distad on the medial surface of the 

 leg, and is continued as the posterior tibial artery (a. tibialis posterior) 

 around the medial malleolus to the plantar surface of the foot. Above 

 the ankle-joint it gives off the malleolar artery (a. malleolaris) to the 

 posterior surface of the distal end of the tibiofibula. 



The popliteal artery, the continuation of the femoral, passes between 

 the medial head of the gastrocnemius on the one hand and the lateral 

 head and the plantaris on the other, reaching the anterior surface of the 

 popliteus, and afterwards the anterior surfaces of the tibia and fibula 

 by passing between their proximal ends. It divides into two branches, 

 the anterior tibial and peroneal arteries. It distributes branches to the 

 muscles about the knee-joint, including a branch to the distal portion of 

 the vastus lateralis, which is given off at about the point of origin of 

 the small saphenous artery. 



The small saphenous artery (a. saphena parva) appears on the 

 proximal portion of the posterolateral margin of the leg, running along 

 the border of the lateral head of the gastrocnemius in company with the 

 corresponding vein and the lesser saphenous nerve. 



The anterior tibial artery (a. tibialis anterior) lies on the medial 

 margin of the peronaeus longus, and passes to the fibular side of the 

 crural ligament in company with the anterior tibial vein and the peroneal 

 nerve to the dorsum of the foot. 



The peroneal artery occupies a more medial position, traversing the 

 leg close to the tibia and the interosseous ligament. It reaches the 

 dorsum of the foot after passing beneath the crural ligament. 



*'^The great saphenous vein (v. saphena magna), a large tributary 

 of the femoral, accompanies the corresponding artery, and the greater 



