CRANIAL NERVES. 439 



Indeed, the ganglia of the sympathetic (ophthalmic, 

 spheno- palatine, and otic) situated on the course of this 

 nerve, at the points where branches are given off to the 

 organs of the senses, seem intended to exert some special 

 influence over the nutrition of those parts. It is well 

 known that if we cut the division going to the nasal mucous 

 membrane, which has the spheno-palatine ganglion con- 

 nected to it, an inflammation in that membrane supervenes 

 which renders smelling impossible. Furthermore, the nutri- 

 tion of the whole side of the face is impaired if the principal 

 trunk of the nerve is divided. 



FACIAL NERVE. The seventh nerve arises at the oblong 

 medulla from grey matter, which is intimately connected 

 with the roots of the trifacial and auditory nerves, and with 

 the anterior olivary body. It leaves the cranium along 

 with the nerve of hearing, from which it is quite distinct, 

 and is distributed to all the muscles of the head except 

 those of mastication. It is essentially the motor nerve of 

 all the muscles of the face, with the exception just referred 

 to. At its root it is exclusively motor, but in its course it 

 acquires some sensitive fibres by its anastomoses with the 

 trifacial, through the petrosal branches of the vidian, and 

 probably through the chorda tympani. In passing from 

 the cranium through the petrous temporal bone, it gives off 

 filaments to the tympanum and muscles of the internal 

 ear, and consequently performs important functions in ad- 

 justing these to suit the sonorous vibrations. 



When this nerve is cut, the whole side of the face is para- 

 lysed ; the eye remains partially open from loss of power 

 in the orbicular muscle of the lids, and is constantly exposed 

 to irritation from dust and other agents ; the sense of hear- 

 ing is impaired, if the section is made within the cranium ; 

 the external ear hangs pendulous ; the nostril is no longer 



