516 MAMMALIAN ANATOMY 



Between the styloid process and the basioccipital is the large 

 posterior lacerated or jugular foramen, the outer wall of which is 

 pierced by the auricular canaliculus for Arnold's nerve. The foramen 

 is divided into two parts by the jugular spine projecting medially 

 from the upper part of the outer wall. The anterior division is for 

 the ninth, tenth, and eleventh cranial nerves ; the posterior, for the 

 beginning of the jugular vein. In front of the lacerated foramen and 

 medial to the tympanic plate is the posterior opening of the carotid 

 canal. In the crest behind the carotid canal is the opening of the 

 tympanic canaliculus for Jacobson's nerve, medial to which is the 

 petrous fossula and the opening of the aquseductus cochleae. On the 

 posterior wall of the carotid canal are the openings of the carotico- 

 tympanic canaliculi. Anterior and medial to the carotid canal is the 

 apex of the petrous, extending forward to the middle lacerated fora- 

 men ; directly anterior to the canal is the Eustachian opening. 



Behind the foramen magnum, on the supraoccipital, is the median 

 external occipital crest, ending behind in the external occipital pro- 

 tuberance. The ridges curving outward and forward from the crest 

 are the inferior and superior curved lines. 



LATEEAL ASPECT. 



The lateral aspect of the human skull shows clearly the globular 

 shape of the cranium and the inferior position of the bones of the 

 face. In the cat's skull the cranium is long and low, and the face is 

 prolonged forward. 



The outline of the lateral aspect of the human skull is irregular. 

 It exhibits the following points, beginning at the top and passing 

 forward : the bregma at the vertex, the glabella at the forehead, the 

 nasion at the root of the nose, the prominent nasal bones, the emargi- 

 nation of the nasal aperture, the nasal spine, at the base of which is 

 the nasal point, the maxillary alveolar border and alveolar point, 

 the teeth, the mental point on the chin, the horizontal line of the 

 body of the mandible, its rounded angle, the almost vertical edge 

 of the ramus of the mandible, the condyle, the tympanic plate of the 

 temporal, the prominent mastoid process, the outline of the basal part 

 of the occipital, the inion on the occipital protuberance, the occipital 

 point marking the greatest convexity of the occipital bone, the lambda, 

 the depression at the obelion, the bregma. 



