170 THE HUMAN BODY. 



-\^ 



each curls around a cms cerebri (the cylindrical mass seen 

 beneath it in the figure, running from the pons Varolii to 

 enter the under surface of the cerebral hemispheres) and 

 appears on the base of the brain. Each goes to one muscle 

 of the eyeball. 



The fifth pair of nerves, V (trigeminales), resemble the 

 spinal nerves in having two roots; one of these is much 

 larger than the other and possesses a ganglion (the Gasse- 

 rian ganglion) like the posterior root of a spinal nerve. 

 Beyond the ganglion the two roots form a common trunk 

 which divides into three main branches. Of these, the 

 ophthalmic is the smallest and is mainly distributed to the 

 muscles and skin over the forehead and upper eyelid; but 

 also gives branches to the mucous membrane lining the 

 nose, and to the integument over it. The second division 

 (superior maxillary nerve) of the trigeminal gives branches 

 to the skin over the temple, to the cheek between the eye- 

 brow and the angle of the mouth, and to the upper teeth;, 

 as well as to the mucous membrane of the nose, pharynx, 

 soft palate and roof of the mouth. The third division 

 (inferior maxillary) is the largest branch of the trigemi- 

 nal; it receives some fibres from the larger root and {ill of 

 the smaller. It is distributed to the side of the head and 

 the external ear, the lower lip and lower part of the face, 

 the mucous membrane of the mouth and the anterior 

 two thirds of the tongue, the lower teeth, the salivary 

 glands, and the muscles which move the lower jaw in mas- 

 tication. 



The sixth pair of cranial nerves ( VI, Fig. 70) or ab- 

 ducentes arise from the posterior margin of the pons Va- 

 rolii, and each is distributed to one muscle of the eye- 

 ball. 



The seventh pair (facial nerves), VII, appear also at 

 the posterior margin of the pons. They are distributed 

 to most of the muscles of the face and scalp. 



The eighth pair (auditory nerves) arise close to the 

 facial. They are the nerves of hearing and are distributed 

 entirely to the internal ear. 



The ninth pair (glossopharyngeals), IX, arising close to- 



