ACOUSTIC NERVE 



309 



Clinical note. If this nerve is paralyzed, the side of the face supplied by 

 the injured nerve droops and is useless, and the eye fails to close. The face 

 will be drawn toward the w-injured side by muscles supplied by the opposite 

 nerve; this is plainly seen if the patient smiles, or attempts to whistle. 



The eighth, or auditory (acoustic), is a sensory nerve. It has 

 two portions the cochlear, or proper nerve of hearing, and the 

 vestibular, or nerve of equilibration. Both pass from the internal 

 ear through the internal auditory canal to the medulla. (See p. 

 333, Nerves of the Internal Ear.) 



FIG. 199. 

 The figures mark the branches of the seventh or facial nerve. (Holdcn.) 



The ninth, or glosso-pharyngeal, is a mixed nerve. The motor 

 fibers pass from the medulla through the jugular foramen and 

 supply the muscles of the tongue and pharynx, as its name suggests. 

 The sensory fibers convey sensations of taste from the tip and back 

 part of the tongue. Bitter things are especially appreciated by the 

 glosso-pharyngeal. 



The tenth, or vagus (pneumogastric), is a mixed nerve. It is 

 traced from the medulla through the jugular foramen. 



Branches. Laryngeal to larynx; pharyngeal to pharynx; car- 

 diac to the heart; pulmonary to the lungs; and others, indirectly, 

 to the stomach, liver, spleen, and intestines. 



It regulates the action of the heart and the act of swallowing; 



