306 



THE NERVOUS SYSTEM 



these cells enter the medulla at the level of the restiform 

 body (Fig. 54). Here they divide into two branches, and 

 end by arborising around groups of cells in close relation to 

 the restiform body. These are the accessory nucleus and 

 the tuberculum acusticum. Here connections are also made 

 with the superior olive. The second neurones starting 



FIBRES TO NUCL.LEMNISCI 

 &CORPORA QUAORICEMINA 



.SA 



FIBRES OF 

 COCHLEAR 

 ROOT 



NERVE-ENDINGS 



IN ORGAN OF CORTI 



,."•, PYRAMID 



Fig. 54. — Connections of the cochlear division of the eighth nerve 

 (from Schafer's Essentials of Histology) : r, restiform body ; V, de- 

 scending root of fifth nerve; tvb. oc, tuberculum acusticum ; n.acc, 

 accessory nucleus ; s.o., superior olive; n.tr., nucleus of trapezium ; 

 n.VI, nucleus of sixth nerve ; VI, issuing root-fibre of sixth nerve. 



from these nuclei cross to the opposite side, superficially 

 by the strise acusticse and deeply by the trapezium. Having 

 crossed, they turn upwards in the lateral fillet and end in 

 the posterior corpora quadrigemina and internal geniculate 

 bodies. From these centres a third group of neurones 

 travels to the superior temporal convolution (Fig. 56, p. 315). 

 Stimulation of this area in the monkey causes the animal 

 to prick up the opposite ear and generally to behave as 



