FRACTURE OF THE TARSAL BONES 71 



metatarsal artery passes with its accompanying vein. Above the groove 

 there are two facets for articulation with the scaphoid, and below it are 

 two other facets, which are articulated to like facets on the cuneiform 

 magnum. 



The anterior, external, and posterior surfaces are roughened and non- 

 articular. 



The cuneiform parvum ossifies from two centres. A slight con- 

 striction passes round the bone, and this indicates the line of fusion 

 of the two parts. Each of these parts is represented in the dog, in 

 which animal they remain separate bones. Such is the case also in 

 the human subject. In rare cases the parts remain separate in the 

 horse. 



Each of the remaining tarsal bones ossifies from a single centre, with 

 the exception of the os calcis, which, in addition to its main centre, has 

 a centre from which the summit of the tuber calcis ossifies. 



FRACTURE OF THE TARSAL BONES 



Of the bones of the tarsus the calcis is the one which is most* 

 exposed to risk of injury since its tuber stands out prominently at the 

 back of the limb, its summit forming the point of the hock. 



This bone is therefore the most frequently fractured, the fracture 

 being usually due to a severe blow or kick received over the part. 

 Owing to its superficial position, when the tuber is fractured diagnosis 

 may be readily made, for the fracture may be detected by simple 

 manipulation. The tendon of the gastrocnemius muscle is inserted into 

 the tuber. When the latter is fractured the tendon is relaxed, as is also 

 that of the flexor perforatus (which gives off slips of insertion into the 

 tuber just below its summit), so that we have the peculiar wobbling of 

 the tendo-achilles which is seen also in rupture of the flexor metatarsi 

 muscle or tendon. The animal is unable to place any weight on the 



