146 
ANATOMY OF THE HOUSE. 
The Outlet presents three notches: two lateral, very exten¬ 
sive ; one middle, considerably smaller. The two former, named 
the great sciatic notches, existing between the posterior borders 
of the ileum and ischium and the sides of the sacrum, are prin¬ 
cipally occupied by the sciatic ligaments, although they give 
transit to the pyramidal muscles, the gluteal and obturator ves¬ 
sels, and the sciatic nerves. The middle notch is the pubic 
arch, formed by the divergence of the ischiatic tuberosities : it 
is occupied in either sex by the urinary canal. 
OF THE HEAD. 
The head is an oblong quadrangular form, broad and flatten¬ 
ed on its sides, narrow and contracted anteriorly and superiorly, 
bulky at the opposite points, hollow interiorly. It is remarkable 
for the prolongation and capaciousness of the parts devoted to 
the formation of the nose and mouth, and for the diminished 
sphere of the cranium. It constitutes the anteriormost part of 
the skeleton, is articulated with the spine from which it is sus¬ 
pended, and is divided into cranium and face. 
% 
I.—THE CRANIUM. 
The cranium -or brain-case is but small when compared with 
the bulk of the body in general: it forms the postero-superior 
part of the head, is prominent and convex superiorly and late¬ 
rally, irregular and in places open inferioriy, hollow and vaulted 
within. It is composed of ten pieces:—three pairs and four 
single bones ; viz. superiorly and anteriorly, of the two frontals; 
superiorly and in the middle, of the parietal; superiorly and 
posteriorly, of the occipital ; laterally, of the four temporals ; 
inferioriy and anteriorly, of the ethmoid; inferioriy and in the 
middle, of the sphenoid ; inferioriy and posteriorly, of the occipi¬ 
tal bone. 
FRONTAL BONES. (OSSA FRONTIS.) 
Situation. The frontal bones form the antero-superior part of 
the cranium, that part which we term the forehead, and which 
in the living horse is commonly marked with a patch of wdiite 
hair, denominated a star. 
Figure. Irregular. Flat, superiorly; concave, underneath. 
Division. Into two surfaces and four borders. 
The External Surface is flat and smooth, sometimes even 
slightly depressed in the situation of the frontal sinus. Pro¬ 
jecting from it outwardly is the external orbital process, forming 
