THE CRANIAL NP:RVES. 



137 



tions of the cavity of the tympanum and of the external auditory 

 canal are of great importance in maintaining normal conditions. 

 They are under the trophic influence of the fifth nerve, both 

 through its auriculo-temporal branch and through its communica- 

 tion with the otic ganglion. The tensor tympani muscle is also 

 supplied by the motor root. Thus, the auditory apparatus is con- 

 siderably under the control of the nerve* 



What painful affections belong to this nerve? 



Headaches of the scalp and deeper tissues, and more especially 

 the frontal sinuses, are common. Toothache and facial neuralgia 



FIG. 39. 



Diagram of the Facial Nerve and its Distribution : 1, Facial nerve at its entrance into the 

 internal auditory meatus ; 2, its exit at the stylo-mastoid foramen ; 3, 4, temporal and 

 posterior auricular branches, distributed to the muscles of the external ear and to the 

 occipitalis; 5, branches to the frontalis muscle; 6, branches to the stylo-hyoid and 

 digastric muscles; 7, branches to the upper part of the platysma myoides; 8, branch 

 of communication with the superficial cervical nerve of the cervical plexus. 



are due to irritation or disease of parts of the nerves. Tic dou- 

 loureux is a persistent neuralgia of some or all of the branches- of 

 the nerve. 



