OSTEOLOGY AND ARTHROLOGY 103 



presents a surface which is moulded on the trochlea of the 

 astragalus ; the median crest of this surface is thick, and 

 descends lower posteriorly than the tuberosities which are 

 situated on the external and internal aspects of this 

 extremity. 



Of the two tuberosities, that which is internal is com- 

 parable to the internal malleolus of man, the one on the outer 

 side forms a sort of external malleolus ; but this latter here 

 belongs to the tibia, and not to the fibula. 



The fibula, in fact, does not reach the inferior extremity 

 of the tibia ; it is a poorly developed bone, elongated and 

 terminating interiorly in a point, at the middle of the shaft 

 of the tibia or at its lower third. Its superior extremity, 

 which is slightly expanded, articulates with the tuberosity 

 which occupies the outer aspect of the corresponding ex- 

 tremity of the tibia. 



The bones of the tarsus are six in number : the calcaneum 

 and astragalus form the upper row ; the cuboid, scaphoid, 

 and two cuneiforms form the lower (Fig. 54). 



The astragalus has not, as in ruminants, an inferior 

 trochlea for articulation with the scaphoid ; this portion of 

 the bone presents a surface which is slightly convex. It 

 articulates with the tibia by a trochlea that occupies not only 

 the superior surface, but also the anterior. This trochlea, 

 which is directed slightly obliquely downwards and outwards, 

 has a very pronounced form ; its lips, which are extremely 

 prominent, determine by their anterior part one of the 

 features which we recognise on the anterior aspect of the 

 ham — a feature which is still more accentuated when the 

 metatarsus {canon) is extended on the leg. On the internal 

 surface of the astragalus is found a tubercle, which forms a 

 projection in the corresponding region of the ham. 



The calcaneum, which is not quite so long as that of 

 the ox, forms by its summit a prominence which is called 

 the point of the ham. 



The cuboid is small ; the scaphoid is large, and flattened 

 from above downwards. Of the two cuneiforms, the more 

 external is the larger ; it closely resembles the scaphoid ; 

 it is flattened from above downwards as is the latter ; but 



