THE CRANIAL NERVES. 225 



in 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 geniculata ganglion, situated on the facial 

 just where it bends to enter the aqueduct of Fallopius. The cen- 

 trally directed branches enter the medulla oblongata around the 

 nerve-cells, in 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 spleno- 

 palatine, 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 sub- 

 maxillary 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 palatopharyngei ; 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, corrugator supercilii, orbicularis 

 palpebrarum, levator labii superioris et alaeque nasi, buccinator, levator 

 anguli oris, orbicularis oris, zygomatici, depressor anguli oris, platysma 

 myoides, etc. 



Properties. Undoubtedly a motor nerve at its origin, but in 

 its course receives sensitive filaments from the fifth pair and the 

 pneumogastric. 



Irritation 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 winking is abolished; the 

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