IQ2 THE NERVOUS SYSTEM 



branches to skin and mucous membrane of the head, central branches by way 

 of the portio major to the brain. Termination in the main sensory nucleus and 

 nucleus of the spinal tract of the trigeminal nerve. 



2. General Somatic Afferent Fiber's. B, Proprioceptive Cells of origin prob- 

 ably located in the mesencephalic nucleus of the fifth nerve. Fibers by way 

 of the portio major, distributed as sensory fibers to the muscles of mastication. 



3. Special Visceral Efferent Fibers. Cells of origin in the motor nucleus of 

 the fifth nerve. Fibers by way of the portio minor and the mandibular nerve 

 to the muscles of mastication. 



VI. Abducens Nerve. Superficial origin, from the lower border of the 

 pons just rostral to the pyramid. Composed of somatic efferent fibers; cells of 

 origin in the abducens nucleus; termination in the lateral rectus muscle of the 

 eye. 



VII. Facial Nerve and Nervus Intermedius. Superficial origin from the 

 lateral part of the lower border of the pons separated from the flocculus by the 

 eighth nerve. Composition (Fig. 120) : 



1. Special Visceral Afferent Fibers. Cells of origin in the ganglion geniculi, 

 chiefly unipolar, with T-shaped axons. The peripheral branches run by way of 

 the chorda tympani and lingual nerves to the taste buds of the anterior two- 

 thirds of the tongue. The central branches run by way of the nervus intermedius 

 to the tractus solitarius and end in the nucleus of that tract. It is probable that 

 the taste fibers terminate in the rostral part of this nucleus. 1 



2. General Visceral Efferent Fibers. Cells of origin in the nucleus saliva torius 

 superior. These fibers run by way of the- nervus intermedius, facial nerve, 

 chorda tympani, and lingual nerve to the submaxillary ganglion for the in- 

 nervation of the submaxillary and sublingual salivary glands. 



3. Special Visceral Efferent Fibers. Cells of origin in the motor nucleus of 

 the facial nerve. These fibers run by way of the facial nerve to end in the super- 

 ficial musculature of the face and scalp, and in the platysma, posterior belly of 

 the digastric, and stylohyoid muscles. 



VIII. Acoustic Nerve. Superficial origin from the lateral part of the lower 

 border of the pons near the flocculus. Consists of two separate parts known as 

 the vestibular and cochlear nerves. 



1 Herrick (1918) describes general visceral afferent fibers in the facial nerve which he says 

 mediate deep visceral sensibility and are probably found in all the branches of the facial. And 

 Rhinehart (1918) has described a cutaneous branch of the facial in the mouse. This branch con- 

 tains general somatic afferent fibers, which arise in the geniculate ganglion and terminate in the 

 skin. 



