THE NERVOUS SYSTEM 221 



and motion, and arises by two roots from the floor of the 

 fourth ventricle of the brain. The sensory root has de- 

 veloped upon it one of the most important ganglia of the 

 head the Gasserian. This nerve gives oft 7 three branches 

 the ophthalmic division of the fifth, the superior max- 

 illary, and the inferior maxillary. (See Fig. 112.) 



The ophthalmic division again divides, giving off the 

 frontal, the lacrimal, and the nasal branches. The 

 ophthalmic is a sensory nerve, and supplies the eyeball, 

 ciliary muscles, iris, lacrimal gland, nasal and ocular 

 mucous membrane, skin, and the muscles of the eyebrow, 

 forehead, and nose. 



The superior maxillary is also a sensory nerve, and is 

 distributed to the temple, cheek, lower eyelid, nose, upper 

 lip, teeth, the palate, and the pharynx. This branch 

 divides again into the several nerves that supply the va- 

 rious parts, as follows : Superior dental, infra-orbital, men- 

 ingeal, two sphenopalatine, and orbital. The superior 

 dental divides into the anterior, middle, and posterior 

 dental. The infra-orbital divides into the palpebral, nasal, 

 and labial. 



The inferior maxillary division of the fifth nerve is 

 subdivided into the meningeal, masseteric, three temporal, 

 buccal, two pterygoids, lingual, auriculotemporal, and 

 inferior dental, which last subdivides into the dental, my- 

 lohyoid, incisive, and mental. The inferior maxillary 

 is a nerve of common sensation and motion. It supplies 

 the muscles of mastication, gums, temples, external ear, 

 teeth, lower lip, tongue, maxillary ganglia, and lower part 

 of the face. 



The sixth nerve, or the abducens, arises from the me- 

 dulla oblongata close to the pons, passes through the 

 sphenoid fissure, and supplies the external rectus of the 

 eye. 



The seventh nerve, or facial nerve, arises as two por- 



