4 
ANATOMY OF THE HORSE. 
Its sides present two triangular slips of rough scabrous surface, 
extending about half way down, marking the places of attach¬ 
ment of the small metacarpal bones. 
The superior extremity presents an articulatory surface, the 
whole of which is flat, with the exception of a part bevelled off 
on its outer side, which articulates with the unciform bone; and 
a small, depressed, bevelled spot on its inner and posterior side, 
which receives part of the trapezoid bone: the flat surface sup¬ 
ports the os magnum, to which in figure it corresponds. In front, 
and rather inclined to its inner side, the extremity has a roughen¬ 
ed prominence, into which is implanted the extensor metacarpi : 
on either side, the bone is asperated by the insertion of lateral li¬ 
gaments ; and the rough part posteriorly gives origin to the sus¬ 
pensory ligament. 
The inferior extremity exhibits an articulatory trochlea, consist¬ 
ing of two equal condyloid surfaces, parted by a semicircular emi-. 
nence, which is fitted into a counterpart formation in the upper 
end of the large pastern bone. These condyles have uneven pits 
in their sides, into which are fixed the lateral ligaments. 
Connexion —Superiorly, with the magnum, unciform, and tra¬ 
pezoid bones; laterally and posteriorly, with the small metacarpal 
bones ; inferiorly, with the large pastern and sesamoid bones. 
SMALL METACARPAL OR SPLINT BONES. 
(OSSA METACARPI PARVA.) 
IS umber —Two :—external and internal. Form. —Elongated ; 
pyramidal. 
Situation —Attached to the lateral and posterior parts of the 
large metacarpal bone. 
Division —Into bases, middles, and apices. 
Extent —They vary somewhat in length : they commonly reach 
about two-thirds of the large bone, downwards. 
The base, or head, is turned upwards, and is surmounted by a 
flat articulatory surface, which enters into the formation of the 
knee-joint. Below this, the bone is tuberous and rough, for liga¬ 
mentous attachment: the external head also receives one of the 
tendons of the flexor metacarpi extemus; the internal receives the 
tendon of the flexor metacarpi internus. 
The middle is trifacial. The anterior surface is asperous, for 
firm attachment to the large bone; the inner surface is excavated, 
to make room for the suspensory ligament; the outer surface is 
smooth and rounded. This part is terminated by a sharp edge 
posteriorly. 
The apex is tapering and ends in a small bony tubercle, which 
inclines backwards, away from the large bone. 
