96 OUTLINES OF EQUINE ANATOMY. 



space is larger. It articulates with os metatarsi inagnum, 

 and posteriorly with the inner splint bone. The anterior 

 margin is convex, most prominent along its central line, 

 and on the inner side, near both the upper and the lower 

 surfaces are rows of foramina. The inner margin is a 

 deep groove, the sides of which meet at an oblique angle. 

 It is everywhere roughened, except at its antero-iuferior 

 angle, where is a small articulatory surface for union with 

 cuneifonne parvum. The external margin presents a shal- 

 lower groove than the internal, and a larger articulatory 

 surface at the antero-inferior part for cuboides. The 

 posterior angle at w^hich these two surfaces meet looks 

 obliquely downwards and backwards, being prolonged su- 

 periorly into a very thin process, with the superior part of 

 which cuneiforme magnum articulates, and os cuboides 

 with the external lateral part. 



CUNEIFORME PARVUM is situated at the postero- 

 internal and inferior part of the hock. It has two surfaces 

 and a process. The superior surface is mainly occupied 

 by a smooth concave articulatory surface looking inwards, 

 bounded anteriorly by a roughened ridge, for articulation 

 with magnum. The inferior surface presents three articu- 

 latory facets. The posterior facet is ovoid and distinct, 

 and articulates with the inner small metatarsal bone, as 

 also does the central facet, which is continuous with the 

 anterior facet for metatarsi magnum, and that in its turn 

 with a small surface for medium on the antero-internal 

 part of the bone. The process is continued from the 

 posterior margin, is flat from side, tuberous, has rounded 

 margins, and curls inwards. It is roughened externally 

 for attachment of ligamentous structure (especially a band 

 running to os cuboides) as are also the interarticular 

 spaces. The roughened depression on the inferior surface 

 is sometimes so deep as to divide the bone into two dis- 

 tinct parts. 



OS CUBOIDES occupies the outer part of the lower 

 row of hock bones, and is equal in thickness to the sum 

 of the two cuneiforme bones (magnum and medium). 

 This thickness is characteristic, and serves to distinguish 

 this from all other bones except os scaphoides of the 

 knee, from which it may be distinguished by the greater 

 number and the smaller size of its articulatory surfaces. It 

 has six surfaces. The anterior smd j)osterior are roughened 



