THE CRANIAL CAVITY 



81 



The apex of the skull is formed by the bodies of the premaxilte and mandible 

 carry mg 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 hone 

 {squamous part) 



Frojital bone 



Paramastoid Occipital hone Sphenoid hone 

 process (hasilar part) {body) 



Fig. 54. — Sagittal Section op Cranium of Horse. 

 1, Lateral wall of foramen magnum; 2, hypoglossal foramen; 3, foramen lacerum posterius; 4, 5, 6, carotid, oval, 

 and spinous notches; 7, floccular fossa; 8, internal acoustic meatus; 9, petrosal crest; 10, hypophyseal or pituitary 

 fossa; 11, groove for maxillary nerve; 12, groove for cavernous 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, internal occipital protuberance; 22, canalis transversus; 23, de- 

 pression 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 frontal sinus. The occipital part 

 is very thick and strong. I 



The lateral wall (Fig. 54) is formed chiefly by the temporal and frontal bones 



and the orbital wing of the sphenoid. It is crossed obliquelj' by the petrosal crest, 



which concurs with the projecting margin of the parietal bone and the tentorium 



osseum in dividing the cavity into cerebral and cerebellar compartments. Behind 



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