

COMPOSITION AND CENTRAL CONNECTIONS OF CRANIAL NERVES 857 





(2) Sympathetic afferent fibers from the pharynx and middle ear are supposed to 

 terminate in the dorsal nucleus. Connections are probably established with motor 

 nuclei concerned in chewing and swallowing; very little is known, however, about 

 the connections with other parts of the brain. 



(3) Taste fibers from the tongue probably terminate in the nucleus of the tractus 

 solitarius. These fibers together with similar fibers from the facial (nervus inter- 

 medius) and the vagus are supposed to form the tractus solitarius and terminate 

 in its nucleus. The central connections have been considered under the vagus. 



(4) Somatic motor fibers to the Stylopharyngeus muscle arise in the upper end 

 of the nucleus ambiguus. The existence of these fibers in the roots of the glosso- 

 pharyngeal is uncertain, as there are other paths by which such fibers might reach 

 the glossopharyngeal from the vagus. The sources of impulses passing to the 

 nucleus ambiguus are considered under the vagus. 



(5) Sympathetic efferent fibers (motor and secretory fibers} arise from the nucleus 

 dorsalis. Some authors believe that the secretory fibers to the parotid gland arise 

 from a distinct nucleus, the inferior salivatory nucleus, situated near the dorsal 

 nucleus. The preganglionic fibers from this nucleus terminate in the otic ganglion; 

 the postganglionic fibers from the otic ganglion pass to the parotid gland. 



The Acoustic Nerve (nil cranial) consists of two distinct nerves the cochlear 

 nerve, the nerve of hearing, and the vestibular nerve, the nerve of equilibration. 



G 14 



14 6 



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FIQ. 760. Terminal nuclei of the cochlear nerve, with their upper connections. (Schematic.) The vestibular 

 nerve with its terminal nuclei and their efferent fibers have been suppressed. On the other hand, in order not to 

 obscure the trapezoid body, the efferent fibers of the terminal nuclei on the right side have been resected in a consid- 

 erable portion of their extent. The trapezoid body, therefore, shows only one-half of its fibers, viz., those which 

 come from the left. 1. Vestibular nerve, divided at its entrance into the medulla oblongata. 2. Cochlear nerve. 3. 

 Accessory nucleus of acoustic nerve. 4. Tuberrulum acusticum. 5. Efferent fibers of accessory nucleus. 6. Efferent 

 fibers of tuberculum acusticum, forming the striae medullares, with 6', their direct bundle going to the superior 

 olivary nucleus of the same side; 6", their decussating bundles going to the superior olivary nucleus of the opposite 

 side. 7. Superior olivary nucleus. 8. Trapezoid body. 9. Trapezoid nucleus. 10. Central acoustic tract (lateral 

 lemniscus). 11. Raph6. 12. Cerebrospinal fasciculus. 13. Fourth ventricle. 14. Inferior peduncle. (Testut.) 



The Cochlear Nerve arises from bipolar cells in the spiral ganglion of the cochlea; 

 the peripheral fibers end in the organ of Corti, the central fibers bifurcate as they 

 enter the cochlear nucleus ; the short ascending branches end in the ventral portion 

 of the nucleus, the longer descending branches terminate in the dorsal portion of 

 the nucleus. From the dorsal portion of the cochlear nucleus axons arise which 

 pass across the dorsal aspect of the inferior peduncle and the floor of the fourth 

 ventricle, the striae medullares, to the median sulcus. Here they dip into the sub- 

 stance of the pons, cross the median plane, and join the lateral lemniscus. Some 



