THE PERIPHERAL NERVOUS SYSTEM. 377 



zygomatic process of the temporal, and joins the Hngual nerve 

 (Fig. 154, /;) (branch of the third division of the fifth nerve). 



On emerging from the stylomastoid foramen the facial 

 nerve (Fig. 155, n) gives off at once a small branch (/;) to the 

 digastric muscle (1), and a larger branch, N. auricularis 

 posterior (r), which passes dorsocaudad about the base of the 

 ear, supplying some of its muscles. Another small branch {d) 

 pierces the cartilaginous external ear and is distributed to its 

 inner surface. The facial nerve then curves craniad about the 

 proximal part of the cartilaginous external ear, and divides five 

 or six millimeters from its emergence into two main branches, 

 which may be designated as the dorsal (/) and ventral {e) 

 rami. A third small branch may also rise from the point of 

 union of the two ; it is usually, however, a twig from the dor- 

 sal ramus, and passes to M. submentalis. 



The dorsal ramus (/) sends two or three small branches 

 to the cheek (including the one just mentioned), and divides 

 into the temporal {g) and the zygomatic (//) branches. The 

 former {g) passes along the cranial margin of the external ear, 

 supplying the superficial muscles, and extends into the tem- 

 poral region, where it lies deeper than the terminal branches 

 of the lachrymal nerve (in) (from the fifth cranial). The 

 zygomatic branch (//) passes across the malar bone to the 

 caudal angle of the eye, sends branches into both eyelids, 

 anastomoses with twigs from the lachrymal branch {111) of the 

 fifth nerve, and passes along the medial side of the eye to the 

 lateral surface of the nose, where it ramifies. 



The ventral ramus (e) gives off a minute branch (/) to the 

 stylohyoid muscle (2), then proceeds toward the angle of the 

 mouth and divides into superior {k) and inferior {J) buccal 

 branches, the former to the muscles of the upper lip and the 

 contiguous regions, the latter to those of the lower lip and 

 chin. 



The seventh nerve thus supplies most of the muscles of the 

 head except those of mastication, and of these it supplies the 

 digastric. 



VIII. N. ACUSTICUS. — The eighth or auditory nerve takes 

 origin (Fig. 138, VIII) from the floor of the fourth ventricle. 



