116 PHYSIOLOGY FOR NURSES 



The twelfth conveys efferent impulses to those mus- 

 cles which depress the hyoid bone, to the tongue and 

 many of the muscles which move that organ. 



While the seventh, or facial, nerve proper contains 

 none but efferent fibers, mainly distributed to those 

 small bundles which move the face and change its ex- 

 pression hence muscles of expression, it is connected 

 with a part intermediate between itself and the auditory 

 called chorda tympani or nerve of Wrisberg, which sup- 

 plies the salivary glands with vasodilator and secretory 

 fibers. The seventh is the nerve concerned in facial 

 paralysis. 



The ninth, or glossopharyngeal, is also a mixed nerve. 

 The motor fibers are distributed to the muscles of the 

 pharynx and base of the tongue, while secretory fibers 

 are carried to the parotid gland. 



The sensory fibers conduct impulses from part of the 

 mucous membrane of the tongue, the pharynx, Eusta- 

 chian tube and tympanic cavity. The origin of this nerve 

 is from the medulla. 



The tenth, vagus or pneumogastric, also springs from 

 the medulla just below the ninth and is, like it, a mixed 

 nerve. It is the most widely distributed of all the cra- 

 nial nerves, some of its branches reaching such function- 

 ally different organs as the larynx, heart, lungs, stom- 

 ach, and intestines, even so far as the large intestine. 

 The motor (efferent) fibers go to the intrinsic muscles 

 of the larynx, while others go to the plain muscles of 

 the digestive tract, including part of the large intestine ; 

 while the afferent fibers bring sensory impulses from the 

 mucous membrane of the larynx, trachea and lungs, 

 esophagus, stomach, intestines, gall bladder and its 

 duct. The nerve carries inhibitory fibers to the heart 

 and secretory fibers to the pancreas and the glands of 



