92 OUTLINES OF EQUIN'E ANATOMY. 



part of the tibia. Below this the surface (internaT) is- 

 smooth, forming (with the tibia) the fibular arch through 

 which the anterior tibial vessels pass. The external sur- 

 face of the button-like superior extremity is occupied by 

 the attachment of the outer lateral ligament of the patella. 

 The greater part of fhe remainder of the external surface 

 gives attachment to peroneus. 



TARSUS, HOCK (ANKLE OF HUMAN SUBJECT), 



consists of a number of small bones resembling to a certain 

 extent those of the knee. It occupies the space between 

 the tibia and the metatarsus, and consists of two roivs of 

 hones, of which the superior is formed by two somewhat 

 large bones, astragalus and calcis, while the inferior con^ 

 sists of four smaller bones, and is split into two rows on 

 its inner side, so that while cuboides occupies the whole 

 depth of the row on the outer side, cuneiforme magnum 

 forms the upper and cuneifoiTae medium and parvum 

 f oi-m the lower subdivision on the inner side. It is between 

 these bones on the inner side that " spavin " generally 

 first manifests itself. 



OS CALCIS is the postero-external bone of the upper 

 row, and articulates by three facets anteriorly mth astra- 

 galus, inferiorly with cuboides. It consists of a hocly and 

 a process. The hodij consists of a large portion externally 

 placed, which presents externally a roughened surface to 

 which ligaments are attached. Internally a very irregular 

 aspect, having at its postero-inferior part a somewhat 

 square projection which superiorly is roughed for attach- 

 ment of the capsular ligament of the hock, posteriorly has 

 a groove coated with fibro cartilage, over which flexor pedis 

 perforans'plays, internally and inferiorly roughened surfaces 

 for ligamentous attachment. Anteriorly a slightly concave 

 oblong aiiiculatory facet extending from above down- 

 wards obliquely inwards for articulation with astragalus. 

 The main portion of the body just above this process on 

 the inner surface presents a small elongated facet looking 

 upwards, inwards, and forwards, which is continuous round 

 an acute articular margin with another facet looking 

 downwards and slightly forwards. The rest of the inner 

 surface running to a point inferiorly is roughened for 



