INTERNAL STRUCTURE OF THE PONS 



part of the central auditory pathway, the connections of which are represented 

 diagrammatically in Fig. 134. 



The superior olivary nucleus is a small mass of gray matter located in the 

 ventrolateral portion of the reticular formation of the pons in close relation to 

 the trapezoid body and not far from the rostral pole of the inferior olivary nucleus 

 (Figs. 108, 110). It consists of two or three separate but closely associated 

 nuclear masses composed of small fusiform nerve-cells, among which there 

 ramify collaterals from the fibers of the trapezoid body. From the dorsal aspect 



Superior vestibular nucleus 



Abducens nerve 



Genu of facial N. / 



Medial longitudinal 

 fasciculus 



Fourth ventricle 



Restiform body 

 Brachium pontis 



Nucleus of abducens N. 

 Facial nerve 



Spinal tract and nu- 

 cleus N. V 



Nucleus of facial N. 

 Thalamo-olivary tract 

 Superior olivary nucleus 



Trapezoid body and 

 medial lemniscus 



Deep stratum of pons 



Corticospinal and cortico- 

 pontine tracts 



Nuclei pontis 



'ficial stratum of pons 



Fig. 108. Section through the pons of a child at the level of the facial colliculus. Pal-Weigert 



method. (X 4.) 



of this nucleus a bundle of fibers, known as the peduncle of the superior olive, 

 makes its way toward the nucleus of the abducens nerve, and it may be that 

 some of these fibers enter the medial longitudinal bundle (Fig. 124). 



The nuclei of the vestibular nerve lie in the floor of the fourth ventricle, 

 where they occupy a field with which we are already familiar, namely, the area 

 acustica (Fig. 89). The vestibular fibers on approaching the rhomboid fossa 

 divide into ascending and descending branches, and terminate in four nuclear 

 masses: (1) the medial (dorsal or principal) vestibular nucleus (Figs. 103, 107), 

 (2) the lateral vestibular nucleus of Deiters (Fig. 107) , (3) the superior vestibular 



