300 



THE ARTICULATIONS 



The arterial supply comes from the anterior tibial, the anterior peroneal, the lateral malleolar, 

 the posterior tibial, and posterior peroneal. 



Relations. — In front and in contact with the anterior ligament, from medial to lateral 

 aspects, are the tendons of the tibialis anterior, the tendon of the extensor hallucis longus, the 

 anterior tibial vessels, the anterior tibial nerve, the tendons of the extensor digitorum longus, 

 and the tendon of the peroneus tertius. To the medial side of the tibialis anterior and to the 

 lateral side of the peroneus tertius the joint is subcutaneous anteriorly. Behind and laterally 

 are the tendons of the peroneus longus and brevis. Behind and medially, from medial to 

 lateral side, are the tendon of the tibialis posterior, the tendon of the flexor digitorum longus, 

 the posterior tibial vessels, the posterior tibial nerve, and the tendon of the flexor hallucis longus. 

 Directly behind is a pad of fat which intervenes between the tendo Achillis and the joint. 

 Below and on the lateral side, crossing the middle fasciculus of the lateral ligament, are the 

 tendons of the peroneus longus and brevis. Below and on the medial side, crossing the deltoid 

 ligament, are the tendons of the tibialis posterior and the flexor digitorum longus. 



Movements. — This being a true hinge joint, flexion and extension are the only movements 

 of which it is capable, there being no side to side motion, except in extreme extension, when the 

 narrowest part of the talus is thrust forward into the widest part of the tibio-fibular arch. 



Fig. 332. — Tne Lower Extremity op the Tibia (Anterior view), to Show the Relation 

 OF the Articular Capsule op the Ankle-joint (in red) to the Epiphysial Line. 



In flexion the talus is tightly embraced by the malleoli, and side to side movement is impossible. 

 Flexion of the ankle-joint is limited by : — (i) nearly the whole of the fibres of the deltoid ligament, 

 none but the most anterior being relaxed; (ii) \hc posterior and middle portions of the lateral liga- 

 ment, especially the posterior; (iii) the posterior ligament of the ankle. It is also limited by the 

 neck of the talus abutting on the edge of the tibia. 



In most European ankle-joints the anterior edge of the lower end of the tibia is kept from 

 actual contact with the neck of the talus in positions of extreme flexion by the intervention of a 

 pad of fat situated beneath the anterior extension of the anterior ligament. In races which 

 adojjt a squatting posture, however, an actual art iculation may bo developed between these two 

 bony surfaces, a facet being i)rcscnt both upon the anterior margin of the til)ia and upon the neck 

 of tfie talus. These facets are known as "s(|uatting facets" (fig. 333, A) and arc of common 

 occurrence in ancient Ijones and in tlie bones of modern oriental people. 



Extension of the ankle-joint is limited by: — (i) the anterior fibres of the deltoid ligament; 

 (ii) the anterior and middle portions of the lat(!ral ligament; (iii) the medial and stronger fibres 

 of the anterior ligament. It is also limited by the posterior portion of the talus meeting with the 

 tibia. Thus the middle portion of the lateral ligament is always on the stretch, owing to its 

 obliquely backward direction, whereby it limits flexion; and its attachment to the fibula in front 

 of the malleolar apex, whereby it prevents over-extension as soon as the foot begins to twist 



