CHAPTER Y. 



MOTOR NERVES OF THE FACE. 



Nerve of mastication (the small, or motor root of the fifth) Physiological anat- 

 omy Deep origin Distribution Properties and functions of the nerve 

 of mastication Facial nerve, or nerve of expression (the portio dura of the 

 seventh) Physiological anatomy Intermediary nerve of "Wrisberg De- 

 cussation of the fibres of origin of the facial Alternate paralysis Course 

 and distribution of the facial Anastomoses with sensitive nerves Summary 

 of the anastomoses and distribution of the facial Properties and functions 

 of the facial Functions of the branches of the facial within the aqueduct 

 of Fallopius Functions of the chorda tympani Influence of various 

 branches of the facial upon the movements of the palate and uvula Func- 

 tions of the external branches of the facial 



THE motor nerves of the face are, the small, or motor 

 root of the fifth, and the portio dura of the seventh, or the 

 facial. The first of these nerves is distributed to the deep 

 muscles, those concerned in the act of mastication, and the 

 second, the facial, supplies the superficial muscles of the face, 

 and is sometimes called the nerve of expression. These 

 nerves are not so simple in their anatomy and physiology as 

 the motor nerves of the eyeball. The nerve of mastication, 

 at its origin, is deeply situated at the base of the brain, and 

 is exposed and operated upon with difficulty. It passes out 

 of the cranium, closely united with one of the great sensitive 

 branches of the fifth, and its distribution has been most suc- 

 cessfully studied by experiments in which it is divided in the 

 cranial cavity. The origin of the facial is also reached with 

 great difficulty. It communicates with other nerves, and 

 its physiology has been most satisfactorily studied by di- 



