72 OUTLINES OF EQUINE ANATOMY. 



the two i*ows are connected together by inter-osseous liga- 

 ments, and by other connecting ligaments. The upper row 

 is formed of four bones, which form the radio-carpal articu- 

 lation with the radius ; between this and the lower row, 

 which is composed of three, sometimes four, bones is the 

 carpal ginglymoid or hinge-like joint, while the lower row 

 forms with the metacarpus an arthrodial or gliding joint, 

 carpo-metacarpal. The four hones of the ujp^er row are 

 the scaphoid, lunar, cuneiform, and trapezium ; those of the 

 lower ro2v, trapezoides, magnum, and unciforme, and 

 sometimes the pisiform bone. 



OS SCAPHOIDES is irregularly cubical, presenting, 

 six surfaces. It is the inner bone of the upper row and 

 articulates with radius, lunare, trapezoides, and magnum. 

 Both its inferior and superior surfaces are articulatory, 

 presenting anteriorly a convexity, continued anteriorly 

 on to the outer surface, posteriorly a concavity. But the 

 concavity is most marked on the inferior surface, and. 

 while that of the superior surface is continued for a short 

 distance on to the posterior surface of the bone, that of 

 the inferior surface does not completely cover that surface, 

 which posteriorly presents a roughened part, projecting, 

 inwards. The tq)i)er surface articulates with the inner 

 prominent portion of the radius. The inferior surface 

 anteriorly (the convex part) with os magnum, posteriorly 

 (the concave part) with os trapezoides. The space between, 

 the reflections of these synovial surfaces which articulate 

 with OS lunare into the outer surface of the bone is flat but 

 rough for attachment of inter-osseous ligaments, as also is 

 a concavity behind it, separated into a deep superior part, 

 and an inferior part by a sharp ridge. Posteriorly the con- 

 cavity is bounded by a roughened ridge, a continuation of 

 the posterior roughened surface of the bone, which is tuberous, 

 below and superiorly presents a continuation of the superior 

 articular surface. This surface is continuous inwardly 

 with the interior and anterior surfaces, both of which are. 

 roughened for attachment of connecting ligaments supe- 

 riorly and inf eriorly, and of the annular ligament centrally. 



OS LUNARE is the centre bone of the upper row. It. is 

 elongated from before backwards, and widest superiorly^ 

 It articulates with the radius, scaphoides, cuneiformCj^ 

 magnum, and unciforme. It presents six surfaces. The^ 

 superior surface is articulatory, convex anteriorly, concave- 



