226 HUMAN PHYSIOLOGY. 



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 

 accumulating between the gums and cheek, from paralysis of the 

 buccinator muscle ; fluids escape from the mouth in drinking ; articula- 

 tion is impaired, the labial sounds being imperfectly pronounced. 



Properties and Functions of the Branches Given off in the 

 Aqueduct of Fallopius. 



1. The large petrosal, when stimulated, gives rise to a dilatation of 

 the blood-vessels and a secretion from the mucous membrane of 

 nose, soft palate, upper part of the pharynx, roof of the mouth, 

 and gums. It therefore contains vaso-motor and secretor fibers, 

 which are in relation with the spheno-palatine ganglion. 



2. The tympanic branch causes the stapedius muscle to contract. 



3. The chorda tympani influences the circulation of the blood around 

 and the secretion of saliva from the submaxillary glands, and 

 through the nerve of Wrisberg governs the sense of. taste in the 

 anterior two thirds of the tongue. Galvanization of the chorda 

 tympani dilates the blood-vessels, increases the quantity and rapidity 

 of the stream of blood, and increases the secretion of saliva. 

 Division of the nerve is followed by contraction of the vessels, 

 an arrest of the secretion, and a diminution of the sense of taste 

 on the same side. It therefore contains vaso-motor, secretor and 

 gustatory nerve-fibers. 



Function. The facial is the nerve of expression, and coordinates 

 the muscles employed to delineate the various emotions, influences the 

 sense of taste and the secretions of the submaxillary and sublingual 

 glands. 



Eighth Pair. Portio Mollis. Auditory Nerve. 



The eighth nerve consists of two portions, a cochlear or auditory 

 and a vestibular or equilibratory. 



Origin. The cochlear portion has its origin in the bipolar nerve- 

 cells of the spiral ganglion located in the spiral canal near the base 

 of the osseous lamina spiralis. The vestibular portion has its origin 

 in the bipolar nerve-cells of the ganglion of Scarpa, located in the 

 internal auditory meatus. 



Distribution. The common trunk of the eighth nerve, consisting 

 of both the cochlear and vestibular portions, emerge from the 



