202 HUMAN PHYSIOLOGY. 



company with the nerve of Wrisberg, and then enters the aqueduct of 

 Fallopius. 



The nerve-fibers composing the nerve of Wrisberg have their origin in 

 nerve-cells in the geniculate ganglion, situated on the facial just where it 

 bends to enter the aqueduct of Fallopius. The centrally directed branches 

 enter the medulla oblongata around the nerve-cells, of which they terminate ; 

 the peripherally directed branches enter the trunk of the facial. 



In the aqueduct the facial gives off the following branches viz.: 



1. The large petrosal nerve, which passes forward to the splenopalatine, or 

 Meckel's ganglion. 



2. The small petrosal nerve, which passes to the otic ganglion. 



3. The tympanic branch, which passes to the stapedius muscle and endows it 

 with motion. 



4. The chorda tympani nerve, which, after entering the posterior part of the 

 tympanic cavity, passes forward between the malleus and incus, through 

 the Glasserian fissure, and joins the lingual branch of the fifth nerve. It 

 is then distributed to the mucous membrane of the anterior two-thirds of 

 the tongue and the submaxillary glands. 



After emerging from the stylomastoid foramen, the facial nerve sends 

 branches to the muscles of the ear, the occipitofrontalis, the digastric, the 

 palatoglossi, and palatopharyngeal; after which it passes through the parotid 

 gland and divides into the temporofacial and cervicofacial branches, which are 

 distributed to the superficial muscles of the face viz., occipitofrontalis, cor- 

 rugator supercilii, orbicularis palpebrarum, levator labii superioris et alseque 

 nasi, buccinator, levator anguli oris, orbicularis oris, zygomatici, depressor 

 anguli oris, platysma myoides, etc. 



Properties. The facial is a motor nerve at its origin, but in its course 

 receives sensitive filaments from the fifth pair and the pneumogastric. 



Stimulation of the nerve, after its emergence from the stylomastoid foramen, 

 produces convulsive movements in all the superficial muscles of the face. 

 Division of the nerve at this point causes paralysis of these muscles on the 

 side of the section, constituting facial paralysis, the phenomena of which are 

 a relaxed and immobile condition of the same side of the face; the eyelids 

 remain open, from paralysis of the orbicularis palpebrarum; the act of wink- 

 ing is abolished; the angle of the mouth droops, and saliva constantly drains 

 away; the face is drawn over to the second side; the face becomes distorted 

 upon talking or laughing; mastication is interfered with, the food accumulat- 

 ing between the gums and cheek, from paralysis of the buccinator muscle; 

 fluids escape from the mouth in drinking; articulation is impaired, the labial 

 sounds being imperfectly pronounced. 



