879 



toward the ventricular cavity. Its dorsiraesal edge is joined to the superior 

 medullary velum; its ventral border is sunjf into the tegmentum, and in its ascent it 

 becomes submerged laterally beneath the lateral lemniscus, dorsally beneath the 

 quadrigeminal plate of the mid-brain. 

 Summary of the Gray Masses in the Pars Dorsalis Pontis; 



Nucleus of Abducent Nerve. 



Nucleus cf Facial Nerve. 



Afferent acd Efferent Nuclei of Trigeminal Nerve. 



Nucleus of Spinal Root of Trigeminal Nerve. 



( Cochlear Division 

 I Vestibular Division 



Nuclei of Acoustic Nerve 



*Superior Olivary Nucleus. 



Nucleus of Trape/ium. 

 *Reticular Ganglionic Formation. 

 ^Nucleus Incertus. 



Nucleus of Lateral Lemniscus. 



( Dorsal Nucleus. 

 \ Ventral Nucleus. 

 ( Medial Nucleus. 

 \ Lateral Nucleus. 

 (. Superior Nucleus. 



Those marked with an asterisk have already been described; the remaining 

 structures relate to the deep connections of several cranial nerves to be described 

 in the succeeding section. 



Central Connections of the Cranial Nerves Attached to the Hind-brain. 

 Eight of the twelve pairs of cranial nerves are attached to the hind-brain portion 

 of the central axis. Their superficial or apparent origin and the cranial foram- 

 ina of exit are enumerated in the table on page 852. In coordination with 

 the internal descriptive anatomy of the hind-brain the central connections of 

 these eight cranial nerves must now be considered. They comprise : 



Purely efferent or motor 

 nerves . 



Mixed nerves . 



Purely afferent or sensor 



XII. Hypoglossal nerve. 

 XI. Spinal accessory nerve. 



VII. Facial nerve (proper). 

 VI. Abducent nerve. 



X. Vagus nerve. 



Motor to muscles of tongue. 



(a) Motor accessory to vagus 



nerve ; 

 (6) Motor to Trapezius and Sterno- 



mastoid muscles. 

 Motor to muscles of scalp and 



face. 



Motor to External rectus muscle 

 of eyeball. 



Sensomotor to respiratory tract 

 and upper part of alimentary 

 tract. 

 IX. Glossopharyngeal nerve. Sensor to tongue (and motor?) 



to Stylopharyngeal muscle. 



V. Trigeminal nerve. Sensor to face, tongue, teeth; 



motor to muscles of mastica- 

 tion. 



fVIII. Acoustic nerve. 



I 



(a) Cochlear division for hearing. 



(b) Vestibular division for equi- 



librium. 



Another nerve which pr.i.^u-.s a remarkably aberrant course, becoming asso- 

 ciated with three of the above-mentioned cranial nerves, is the nervus intermedius, 

 known peripherally as the chorda tyinpani. It is chiefly sensor (taste) in function, 

 but also contains efferent fibres which are excitoglandular for the submaxillary 

 and sublingual salivary glands. 



In the hind-brain axis lie certain gray masses which are functionally homol- 

 ogous with the nuclear masses in the different parts of the spinal central gray. 



