GRAY MATTER OF MEDULLA. 



305 



cells of the terminal nucleus of the vagus nerve, which represent 

 neurones of the posterior columna of gray matter. They receive 

 the end-tufts of the sensory root fibers of the vagus nerve and 

 possibly of a small number from the glossopharyngeal nerve. 



The hypoglossal nucleus, the motor part of the nucleus of the 

 ala cinerea and the nucleus ambiguus receive many fibers from the 

 opposite pyramidal tract, and probably from the cerebro-pontal 

 tracts, which bring to them voluntary motor and inhibitory im- 



Anterior cere- 



bello-spinal, 



spino-thalamic 



and triangular tracts 



Inferior olivary nucleus 



Medial accessory olivary nuc. 



Medial and an- 

 terior longitu- 

 dinal bundles 



Ascending Ant. 

 cerebello- 

 spinal, spino- 

 thalamac and 

 rubrc spinal 

 tracts 



Triangular 

 tract (Helwigi) 



Descending ant. cerebello- 

 Medial fillet spinal tract 



Fillet decussation 



Fig. 94. Section of the medulla oblongata at the fillet decussation. (Original.) 



pulses from the cerebral cortex; and their reflex connection is estab- 

 lished by fibers of the medial longitudinal bundle which rise in 

 sensory nuclei. 



The posterior columna is decapitated by the fillet. It is repre- 

 sented in the medulla (i) by the following terminal nuclei, viz., 

 the sensory part of the nucleus alae cinereae of the vagus and 

 glossopharyngeal nerves, the vestibular and cochlear nuclei of 

 the auditory nerve, the nucleus tractus solitarii and the nucleus 

 of the spinal tract of the trigeminal nerve; and (2) by the gray 

 matter of the reticular substance of the posterior area. 



