CHAPTER XXXVII. 

 THE ANKLE JOINT. 



DESCRIPTION. ORDER OF STRUCTURES 



MOVEMENTS. SURROUNDING JOINT. 



DISEASES. TENOTOMY. 



The ankle joint is a ginglymus or hinge joint, and is 

 formed by the reception of the astragalus in a cavity, com- 

 posed of the lower articular end of the tibia and of the 

 malleolus on either side. The ligaments of the joint are 

 external and internal, anterior and posterior. The former, 

 i.e., the external lateral, is composed of three parts; one, 

 stretching from the external malleolus to the astragalus ; 

 another the middle fasciculus from the same malleolus 

 to the peroneal tubercle of the os calcis, and a third, from 

 the posterior border of this malleolus to the astragalus. 

 The internal lateral or deltoid ligament, from the inner 

 malleolus, is attached to the scaphoid in front, the sus- 

 tentaculum tali below, and the astragalus behind, while 

 the anterior and the posterior ligaments are attached 

 above, to the tibia, and, below, to the astragalus. 



Movements. It is so embraced by the malleoli that 

 movement at this joint is limited to flexion and extension, 

 with the exception, that, in extreme extension, in which 

 position the narrowest portion of the astragalus rests upon 

 the widest part of the joint cavity, there is, in addition, a 

 slight amount of lateral motion permitted. Flexion is 

 limited by the posterior and middle portions of the exter- 

 nal lateral ligament, by the posterior ligament of the ankle 

 joint, by most of the fibres of the internal ligament and by 

 the neck of the astragalus abutting on the front of the 

 tibia, whereas, extension is limited by the anterior fibres 



