424 
ANATOMY OE THE HORSE. 
COCCYGEAL REGION. 
An anatomical knowledge of the muscles composing the tail 
is indispensable to the scientific performance of the operation of 
nicking. 
In denuding them (in dissection) the skin will be found to 
grow soft and thin upon the under part of the tail, where there is 
no hair; but thick again and coarse as it approaches the tip, at 
which pail it is also more closely adherent to the muscle, in con¬ 
sequence of the little cellular substance there is interposed. 
These muscles are divisible into four pairs; and most com¬ 
pletely so at their origins at the root of the tail: in the course of 
their progress their nearest fibres unite together, and become 
blended one with another. 
erector coccygis. — ( Sacro-coccygeus superior.) 
Situation. —Supero-lateral part of the tail. 
Form . —Elongated; pyramidal. 
Attachment .—Anteriorly and superiorly, to the transverse pro¬ 
cesses and spines of the sacrum ; posteriorly and inferiorly, to the 
bodies and spines of the bones of the coccyx. 
Relations .—The muscle lies in the hollow formed by the 
sacrum on the inner side, and the ileum and sacro-sciatic liga¬ 
ment on the outer side. 
Structure .—Superior attachments, tendinous and fleshy ; infe¬ 
rior, chiefly fleshy; though, here and there, slips of tendon pierce 
its belly and take root in the bone. The muscle, altogether, is 
remarkable for its tendinous appearance externally ; and for being 
somewhat complex in its composition: consisting, exteriorly, of 
a flat tendon, from which slips are detached in its course along 
the tail, after a penniform manner, across its fleshy belly; 
while the interior part is fleshy, and grows pale and narrow in its 
course, and is everywhere closely adherent to the coccygeal 
bones. Towards the extremity of the dock, the tendons so pre¬ 
dominate over the fleshy fibres, that it is through them alone 
that the muscle can be distinctly traced to its termination. 
Action. —To erect the tail. If one muscle act by itself, the 
tail at the time of elevation will be carried to one side. Some 
horses have such power of action with these muscles, that they 
can reflex the tail over the croup, or curve it to either side, 
around the quarter. 
depressor coccygis. —( Sacro-coccygeus inferior.) 
Situation.~hA%xo \d,tQx r d\ part of the tail. 
