346 
ANATOMY OF THE HORSE. 
pital cupula^ for covering the cerebellum.—2d, On either side, 
along the same line, the cerebral concavities of the frontal bone; 
the cor07ial {suturey the boundary line between them and the 
parietal concavities; the transverse grooves sinuses ; 
and, sunk within them, the lambdoidal suture. 
The rase is formed by the temporal, sphenoid, ethmoid, and 
occipital bones. It presents—1st, on the middle line, from before 
backwards, the crista galliy and on its sides the ethmoidalfossce and 
cribriform plates^ bounded laterally by the internal orbital plates 
of the frontal bones, and then pierced by the internal orbital 
foramina; the concave surface of the body of the ethmoid bone; 
the optic hiatus leading to the optic foramina; a transverse 
suture between the ethmoid and sphenoid bones. Upon the 
sphenoid bone, the pituitary fossa, bounded laterally by the two 
optic fossce; the latter leading to the foramina lacera orbitalia, 
over which are the spinal foramina : a transverse elevated line 
denotes the place of junction of the sphenoid with the occipital 
bone. Belonging to the occipital bone are the basilar fossa and 
the occipital hole. 2d, On either side, in the same direction, the 
internal surface of the wing of the ethmoid bone, rather more con¬ 
vex than concave, for the support of the anterior lobe of the cere¬ 
brum ; the concavity of the wing of the sphenoid bone, for the re¬ 
ception of the middle lobe; the concavity of the squamous part of 
the temporal bone, for lodging the posterior lobe : and the sutures 
bounding these three cerebral surfaces. The foramen lacerum 
basis cranii, formed between the wing of the sphenoid anteriorly, 
the basilar process of the occipital bone internally, and the petrous 
portion of the temporal bone externally and posteriorly: it is wide 
and irregular before, narrow behind, and is distinguished into 
thespheno-occipital^ndi temporo-occipitalhiatus. The petrous 
PORTION OF THE TEMPORAL BONE, presenting a narrow tri¬ 
angular surface forwards and upwards, which contributes to the 
posterior cerebral concavity; a broad smooth but uneven surface 
inwards, against which inclines the cerebellum, and upon which 
we distinguish— a, the orifice of the meatus auditorius internus; 
b, a transverse prominence, and several cerebral indentations; 
c, an irregular convexity downwards, which forms the boimdaiy 
wall of the labyrinth ; d, a fissure separating it from the fonner. 
Lastly, the sutures, uniting the petrous to the squamous portion 
and to the occipital bone. The occipital bone, a part of 
the internal surface assisting in the foimation of a conca\Tty for 
the cerebellum, by the convolutions of which it is indented ; the 
surface even and smooth, and slightly excavated below this, for 
the support of the medulla oblongata; still lower, the condyloid 
foramina, through which the ninth pair of neiwes pass out. 
