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THE NERVE SYSTEM 



the Platysma and Depressor anguli oris, supplying the muscles of the lower lip and 

 chin, and communicating with the mental branch of the inferior dental nerve. 



The cervical branch (ramus colli) runs forward beneath the Platysma, and forms 

 a series of arches across the side of the neck over the suprahyoid region. A branch 

 descends vertically to join with the superficial cervical nerve from the cervical 

 plexus; others supply the Platysma. 



Terminationsi 

 of supratrochlear. 



of infratrochlear 

 of nasal. 



FIG. 741. The nerves of the scalp, face, and side of the neck. 



Applied Anatomy. The facial nerve is more frequently paralyzed than any of the other 

 of the cranial nerves. The paralysis (facial palsy) may depend either upon (1) central causes 

 *. e., blood clots or intracranial tumors pressing on the nerve before its entrance into the 

 internal auditory meatus. It is also one of the nerves involved in bulbar paralysis. Or (2) it 

 may be paralyzed in its passage through the petrous bone by damage due to middle-ear disease 

 or. by fractures of the base of the skull. Or (3) it may be affected at or after its exit from the 

 stylomastoid foramen. This is commonly known as Bell's paralysis. It may be due to exposure 

 to cold or to injury of the nerve, either from accidental wounds of the face or during some surgical 

 operation, as removal of parotid tumors, opening of abscesses, or operations on the mandible. 



When the cause is central, the abducent nerve is usually paralyzed as well, and there is also 

 hemiplegia on the opposite side. In these cases the electric reactions are the same as in health; 

 whereas, when the paralysis is due to a lesion in the course of the nerve, the reactions of degenera- 

 tion develop." When the nerve is paralyzed in the petrous bone, in addition to the paralysis of the 

 muscles of expression, there is loss of taste in the anterior part of the tongue, and the patient is 



