520 MAMMALIAN ANATOMY 



sphenoid ; a transverse ridge separates the latter surface from the optic 

 groove for the optic chiasm, which terminates laterally at the optic 

 foramina. Behind the groove is the olivary eminence, separated on 

 each side from the anterior clinoid process by the notch for the carotid 

 artery. The sella turcica, for the pituitary process of the brain, 

 occupies the space between the olivary eminence in front and the 

 square plate of bone, the dorsum sellse, behind. It is bounded 

 laterally by the carotid groove, which extends backward on the 

 lingula of the sphenoid and ends in the middle lacerated foramen. 

 Each superior angle of the dorsum sellse is prolonged as a posterior 

 clinoid process, beneath which the lateral margin is notched for the 

 passage of the third cranial nerve. The sloping surface extending 

 from the upper edge of the dorsum sellse to the foramen magnum 

 is called the clivus. Beneath the anterior clinoid process are the 

 sphenoidal fissure, or anterior lacerated foramen, and the foramen 

 rotundum ; the former transmits the third, the fourth, the three 

 branches of the ophthalmic division of the fifth, and the sixth nerve, 

 some branches of the sympathetic plexus, the orbital branch of the 

 middle meningeal artery, a recurrent branch of the lachrymal artery, 

 and the ophthalmic vein. The foramen rotundum transmits the supe- 

 rior maxillary division of the fifth nerve. Further back and to the 

 side is the large foramen ovale, for the inferior maxillary division of 

 the fifth nerve, the small meningeal artery, and the small petrosal 

 nerve. Lateral to the foramen ovale is the small foramen spinosum ; 

 it transmits the middle meningeal artery, which ascends forward in a 

 groove on the squamous of the temporal. Behind these foramina, 

 and separated from them by the spheno-petrosal lamina, is the middle 

 lacerated foramen for the carotid artery, the Vidian nerve, and a 

 branch from the pharyngeal artery. 



At the apex of the petrous in the lacerated foramen is the anterior 

 opening of the carotid canal, and on the anterior surface is the depres- 

 sion for the Gasserian ganglion of the fifth nerve. Lateral to these 

 features is the small hiatus Fallopii for the petrosal branch of the 

 Vidian nerve and the petrosal branch of the middle meningeal artery. 

 Anterior and lateral to the hiatus is the opening for the small super- 

 ficial petrosal nerve, a branch of Jacobson's nerve from the tympanum. 

 Behind these foramina is the eminentia arcuata, produced by the 

 superior semicircular canal of the labyrinth. The thin roof of the 



