THE ANKLE-JOINT. 



17: 



a small aperture for the passage of the anterior branches of the peroneal 

 vessels. 



Fig. 154. — Articulations of the Knek, Leg and Ankle, seen Fig. 154. 



FROM BSFORE. i . 



1, superior anterior tibio-fibiilar ligament ; 2, interosseous mem- / , 



brane ; 3, the anterior inferior tibio-fibular ligament ; 4, internal j ,1 



lateral ligament of the ankle-joint; 5, middle vertical part (cal- /\ \\\ 



caneo-fibular) of the external lateral ligament of the ankle-joint ; 

 6, anterior part (talo-fibular) of the same ; 7, anterior ligament of 

 the ankle-joint. 



Iiower tibio-fibular articulation. — The inferior 

 extremities of the tibia and fibula are in contact by 

 snrftices which for the most part arc rough and bound 

 together by ligament, but near their lower edges are 

 smooth and covered by cartilage. The tibial sur- 

 face is concave, the fibular convex ; but the lower 

 edges of both surfaces arc straight. The strong short 

 fibres which pass directly between the opposed sur- 

 faces form the infonor inferosseous ligament. The 

 (inferior lif/avmit is a flat band of fibres, extended 

 obliquely over the lower part of the bones, the 

 direction of its fibres being downwards from the 

 tibia to the fibula. The posferior ligament, some- 

 what triangular, is similarly disposed behind the 

 articulation ; its outer surface is covered by the 

 peronei muscles. The transverse ligament, longer 

 and narrower than the preceding, is placed imme- 

 diately below it ; its fibres are horizontal, and extend 

 fi-om the external malleolus to the contiguous part 

 and hinder border of the articular surface of the tibia; 

 it closes the interval between the bones. 



The sgnovial cavity lying between the small articu- 

 lar surfaces is an extension of that of the ankle-joint. 



THE ANKLE-JOINT. 



In this articulation, which is a hinge joint, the inferior extremi- 



Fig. 155. — The Lower Tibio-Fibular Articulation and 

 Ankle-Joint, from behind. 



1, inferior posterior tibio-fibular ligament ; 2, transverse 

 ligament ; -3, posterior fibres of the internal lateral ligament 

 of the ankle-joint ; 4, middle, and 5, posterior part of the 

 external lateral ligament of the ankle-joint ; (J, posterior 

 talo-calcaneal ligament. 



ties of the tibia and fibula are united so as to 

 present a three-sided hollow, which embraces 

 the astragalus, and renders lateral movement 

 impossible when the ligaments are tense. 



The internal lateral or deltoid ligament 

 is a flat fasciculus of fibres, much broader at 

 the lower than at the upper part. One ex- 

 tremity is attached to the groove on the inferior border of the internal 



