228 



DISSECTION OF THE LEG. 



Articular surfaces. Both bones are flattened towards the outer 

 part of the articulation ; but at the inner side the os cah-is 

 is hollowed transversely, and the cuboid bone is convex to fit 

 into it. 



Movement. In this joint the cuboid bone may move in two direc- 

 tions, viz., obliquely down and in with inversion of the foot, and 

 up and out with eversion. 



In the downward movement the internal lateral and the upper 

 ligament are made tight ; and in the upward, the calcaneo-cuboid 

 ligaments of the sole are stretched. 



TRANSVERSE TARSAL ARTICULATION. This name is given to the 

 line of articulation crossing the foot between the astragalus and os 

 calcis behind and the navicular and cuboid bones in front : it will 

 be noticed, however, that it is not a continuous joint, but is com- 

 posed of two separate articulations, viz., the astragalo-navicular and 

 the calcaneo-cuboid. 



These joints participate, as has been already seen, in the move- 

 ments of inversion and eversion, the anterior bones moving over 

 the hinder ones, downwards and inwards in inversion, and upwards 

 and outwards in eversion. It is at this line that the foot is 

 divided in the operation known as Chopart's amputation. 



Dissection, Saw through the astragalus in front of the attach- 

 ment of the interosseous ligament between it and the os calcis, and 

 remove the head of the bone in order to see the disposition of the 

 inner and outer calcaneo-navicular ligaments. 



Then the interosseous ligament uniting the astragalus and the os 

 calcis is to be cut through, to demonstrate its attachments, the 

 articular surfaces of the bones, and the sy no vial sacs (p. 225). 



Articular surfaces of the two hinder tarsal bones. There are two 

 articular surfaces, anterior and posterior, to both the astragalus and 

 the os calcis. The hinder one of the os calcis is convex from before 

 back, and the anterior is concave ; but sometimes the latter is 

 subdivided into two. The surface of the astragalus has a form 

 exactly the reverse of that of the os calcis, viz., the hinder one 

 concave and the anterior convex ; the anterior is seated on the head 

 of the astragalus. 



Dissection. The calcaneo-cuboid joint may be opened to see the 

 articular surfaces ; and the student is to keep in mind that all the 

 other articulations of the foot are to be opened for the like purpose, 

 even should directions not be given. 



Union of the ARTICULATION OF THE NAVICULAR BONE. The navicular bone 



bone is united in front to the three cuneiform bones, and laterally to the 



cuboid. 



Surfaces of 

 bones. 



Movement : 



state of 

 ligaments. 



Transverse 



tarsal arti- 

 culation 



includes 

 two joints : 



movements 



amputation 



practised 



here. 



Dissection. 



Surfaces of 

 os calcis 



and astra- 

 galus. 



tothecunei- 



In the articulation with the cuneiform bones (fig. 87) there are 

 three longitudinal dorsal ligaments (i, k, I), one to each bone ; but 

 the innermost is the strongest and widest, and extends round the 

 inside of the articulation into the sole of the foot (fig. 89, e). 



The place of plantar bands is supplied by processes of the tendon 

 of the tibialis posticus. 



The naviculo-cuiieiform articulations form one continuous joint, 



J 



