THE CRANIAL NERVES 287 



the stapedius muscle, and (b) the chorda tympani, which passes 

 through the cavity of the tympanum and emerges by a foramen at 

 the inner end of the Glaserian fissure to go to the lingual branch 

 of the fifth. (2) At its exit from the stylo-mastoid foramen it 

 gives off (a) a posterior auricular branch which, receiving a 

 filament from the auricular branch of the tenth, is distributed to 

 the retrahens aurem and the occipital portion of the occipito- 

 frontalis; (b) a digastric branch to the posterior belly of the di- 

 gastric muscle; (c) a stylo-hyoid branch to the muscle of that 

 name. (3) On the face it divides into (a) a temporo-facial 

 branch, which is % distributed to the muscles over the temple and 

 upper face; and (b) a cervico-facial branch, which is distributed 

 to the lower face and upper cervical region. 



Functions. This is the motor nerve of the muscles of ex- 

 pression, of the platysma, buccinator, digastric (posterior belly) , 

 stylo-hyoid, the muscles of the external ear and the stapedius. 

 Communicating freely with the fifth, it also contains sensory 

 fibers, but it is in all probability insensible at its root. Its sec- 

 tion causes paralysis of the muscles which it supplies, but no 

 marked changes in sensation. The branches to the otic and 

 spheno-palatine ganglia in the aqueductus Fallopii constitute 

 their motor roots; the branch given off in this situation to the 

 tenth supplies it with motor filaments, and probably also here pass 

 sensory fibers from the tenth to the seventh. In facial paralysis 

 when the lesion is in the aqueductus Fallopii or behind it, there 

 is paralysis also of the muscles of the palate and uvula, the uvula 

 is drawn to the opposite side and there is trouble in deglutition. 

 The fibers to the azygos uvulae and levator palati pass from 

 the aqueductus Fallopii through Meckel's ganglion. 



The effect of paralysis of the facial upon the superficial muscles 

 of the face is suggested in its distribution. The brow cannot be 

 corrugated; the eye is constantly open and there may be con- 

 sequent inflammation from exposure; the nostril cannot be di- 

 lated, and inspiration and possibly olf action are interfered with; 



