A TEXTBOOK OF PHYSIOLOGY 



dorsally to the mesial fillet {Fig. 425). More dorsal still, in a position 

 corresponding to that in. the medulla obJongata, lies the posterior 

 longitudinal bundle, its fibres making connections both upwards and 

 downwards. 



The chief masses of grey matter are 1. Deiters' nucleus. 2. The 

 nucleus pontis. 3. The superior olive.] 4. The nuclei of the eighth 

 to the fifth cranial nerves. 



The Nucleus of Deiters is an important mass of grey matter lying 

 at the lower end of the pons, and partly in the upper part of the 

 spinal bulb. Around the large cells constituting the nucleus end fibres 

 from the vestibular nerve and the dentate nucleus of the cerebellum. 



FIG. 428. PLAN (TRANSVERSE) OF THE ORIGIN OF THE SIXTH AND OB THE MOTOR 

 PART OF THE SEVENTH NERVE. (E. A. Schaier, from " Qaain's Anatomy.") 



VI., Sixth nerve; VII., seventh nerve; a.VII:,- ascending part of root of seventh, 

 shown cut across near the floor of the fourth ventricle ; g, genu of seventh nerve- 

 root ; n. VI., chief nucleus of the sixth nerve ; n.' VI., accessory nucleus of sixth ; 

 n.VII., nucleus of seventh; d.V., descending root of fifth; pyr., pyramid bundles; 

 VIII.v., vestibular root of eighth nerve. 



From the cells of the nucleus arise fibres which pass downwards through 

 the medulla oblongata, into the aiitero-lateral position of the cord the 

 vestibulo-spinal tract. Other fibres pass inwards to the middle line, 

 to ascend and descend in the posterior longitudinal bundle (Fig. 427). 

 The ascending fibres go chiefly to the sixth and third nuclei, the 

 descending to the anterior horn cells of the cord. In close proximity 

 to this nucleus, forming in reality its upper part towards the cere- 

 bellum, is the nucleus of Bechterew. 



The Nucleus Fontis is the name given to the grey matter lying 

 between the crossing fibres of the pons, around the cells of which 

 end fibres from the frontal and occipital cortex the fronto-pontine 



