50 THE ANATOMY OF THE HORSE. 



bone. The other passes from the unciform to the head of the external • 

 small metacarpal bone, under cover of the lateral ligament. The two 

 interosseous pass, one on each side, from the point of articulation of 

 the large and small metacarpal bones, to join the interosseous ligaments 

 connecting the bones of the lower row. 



Directions. — Attention may at this stage be given to the disposition 

 of the synovial membranes of the carpus, which are three in number. 



Synovial Membranes. — 1. The radio-carpal synovial membrane not 

 only facilitates the movements between the radius and the bones of the 

 upper row, but also descends between the latter bones so far as their 

 interosseous ligaments. 2. The inter-carpal synovial membrane, in the 

 same way, belongs to the inter-carpal transverse joint ; but it is also 

 insinuated above, between the "bones of the upper row as far as their 

 interosseous ligaments, and descends in the same way below, between 

 the adjacent bones of the lower row. It communicates with the next. 

 3. The carpo-metacarpal synovial membrane facilitates the movements 

 between the lower row and the heads of the metacarpal bones, ascends 

 between the adjacent bones of the lower row as far as their interosseous 

 ligaments, and dips down to supply the articulations between the large 

 and small metacarpals. 



Directions. — The radio-carpal, inter-carpal, and posterior common 

 ligaments should now be cut transversely. The upper row will thus be 

 isolated as a single piece for the examination of its special ligaments. 



The Ligaments of the Upper Row are three anterior and three 

 interosseous ; and they are extremely simple. The anterior ligaments 

 are flattened bands connecting the adjacent bones in front, while the 

 interosseous bands are very short and connect the contiguous surfaces 

 of the bones. 



The Ligaments of the Low t er Row are two anterior, and two inter- 

 osseous ; and they are disposed like those of the upper row. In 

 examining these, the lower tier of bones must not be separated from 

 the metacarpus, as that would involve the destruction, in part, of the 

 suspensory ligament of the fetlock. 



The Intermetacarpal Articulations. The head of the large meta- 

 carpal bone responds to one of the small metacarpals on each side by a 

 small synovial joint lubricated by an extension of the carpo-metacarpal 

 synovial membrane. Below that point the union of the bones is main- 

 tained by short interosseous fibres, which, in adult animals, are very 

 frequently ossified. The lower extremities of the splint bones, however, 

 for a short distance above the little knob that terminates them, remain 

 freely movable, as may be felt by manipulation in the living animal. 

 In addition to the interosseous fibres, the ligaments of the carpus which 

 get inserted in common into the heads of both large and small meta- 

 carpal bones contribute to the union of these bones. 



