74 THE SURGICAL ANATOMY OF THE HORSE 



the bottom of which is the line of apposition of the articular surfaces. 

 The ridge on the cuneiform magnum forms the upper boundary of a 

 second transverse groove, the lower boundary of which is formed by the 

 prominent anterior border of the upper extremity of the large and the head 

 of the inner small metatarsal bones. There is also a groove disposed 

 vertically connecting these, and continued downwards between the 

 large metatarsal bone and the head of the inner small metatarsal (see 

 Plate XVni. and chapter i.). 



Passing over the anterior aspect of the scaphoid and cuneiform 

 magnum is the thin, sheet-like astragalo-metatarsal ligament, whilst the 

 cunean branch of the flexor metatarsi tendon passes to its insertion into 

 the small cuneiform bone. The joint is closed anteriorly by the thin 

 anterior common ligament. The anterior root of the internal saphena 

 vein runs upwards and forwards across the cuneiform magnum and the 

 scaphoid, but subcutaneously placed, whilst a slender cutaneous branch 

 from the posterior tibial nerve runs obliquely downwards and forwards 

 over these bones. 



The ridges and grooves above are considered by some to be of great 

 diagnostic importance in connection with spavin. Others, again, treat 

 them with indifference. Amongst the latter are some who base their 

 opinion on the ground that the presence of the ligaments renders the detec- 

 tion of the grooves by palpation impossible. In support of this contention 

 Wooldridge drove nails into hocks in those situations where he presumed 

 the grooves to be present, and these experiments led him to conclude that 

 the grooves could not be located. His experiments were obviously 

 performed on the dead subject, and much value cannot be attached to 

 them, on account of the greater pliability and suppleness of the structures 

 in the living animal, together with the power to relax the ligaments, &c., 

 by flexing and extending the joint at will, which the observer of the 

 living animal possesses. It will be readily conceded that in animals with 

 thick, coarse skins there will be greater difficulty experienced in locating 

 the grooves and ridges, and in some such subjects it might be even 



