THE CRANIAL CAVITY é 81 
The apex of the skull is formed by the bodies of the premaxillee and mandible, 
carrying the incisor teeth. 
THE CRANIAL CAVITY 
This cavity (Cavum cranii) incloses the brain, with its membranes and vessels. 
It is relatively small and is ovoid in shape. 
The dorsal wall or roof (Calvaria) (Fig. 52) is formed by the supraoccipital, 
interparietal, parietal, and frontal bones. In the middle line is the internal parietal 
crest, which joins the crista galli in front, and furnishes attachment to the falx 
cerebri. Posteriorly the crest is continued by the sharp anterior margin of the 
Occipital bone 
(squamous part) Parietal bone 
Frontal bone 
Paramastoid — Occipital bone Sphenoid bone 
process (basilar part) (body) 
Fic. 54.—Sacirrart Section of Crantum oF Horse. 
1, Lateral wall of foramen magnum; 2, hypoglossal foramen; 3, foramen laccrum posterius; 4, 5, 6, carotid, oval, 
and spinous notches; 7, floccular fossa; 8, internal acoustic meatus; 9, petrosal crest; 10, hypophyseal or pituitary 
pons (Fossa pontis) depression below 12 is the hypophyseal fossa; 11, groove for maxillary nerve; 12, groove for cay- 
ernous sinus; 13, optic foramen; 14, 14, sphenoidal sinus; 15, crista galli; 16, perpendicular plate of ethmoid bone; 
17, vomer; 18, septum between frontal sinuses; 19, orbital wing of sphenoid; 20, temporal wing of sphenoid; 21, in- 
ternal occipital protuberance; 22, canalis transversus; 23, depression for vermis cerebelli. 
tentorium osseum, which projects downward and forward into the cavity, and gives 
attachment to the tentorium cerebelli by its sharp lateral edges. Behind this the 
roof is grooved centrally for the middle lobe or vermis of the cerebellum. Trans- 
verse grooves pass from the base of the tentorium osseum to the temporal canals. 
The anterior part of the roof is hollowed by the fronta: sinus. The occipital part 
is very thick and strong. 
The lateral wall (Fig. 54) is formed chiefly by the temporal and frontal bones 
and the orbital wing of the sphenoid. It is crossed obliquely by the petrosal crest, 
which concurs with the margin of the parietal bone and the internal occipital pro- 
tuberance in dividing the cavity into cerebral and cerebellar compartments. Behind 
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