Chap, ii.] 



THE BRAIN. 



755 



excited, nervous impulses accompanied by ' currents of action ' 

 pass downward along the fibres of the pyramidal tract. 



The results of stimulating the fibres of the tract in their 

 course through the corona radiata and the internal capsule and 



trP gr.P 



Fig. 130. Throdgh the Pons at the exit of the Fifth 



Nerve. (Sherrington.) 



(In the line 112, Fig. 108.) 



C. B. Remains of restif orm body. 8. P. superior peduncle of the cerebellum. 

 F. m. median, F. 1. lateral Fillet. T. B. tegmental reticular formation, tr. P. 

 superficial transverse fibres of the Pons. I. posterior longitudinal bundles. V. s. 

 superior vermix ; sections of three folia are shewn, one being detached ; between 

 them the intervening sulci laid open by the section are seen. VI. a. valve of 

 Vieussens or anterior velum, r. raphe. Py. Pyramidal fibres, gr. P. grey mat- 

 ter of the Pons. s. o. superior olive, t. placed on the left side indicates the posi- 

 tion of a bundle of longitudinal fibres which may be traced forward into the 

 subthalamic regions. V. m. motor nucleus, V. s. sensory nucleus, and V. roots 

 of the fifth nerve. 



4th. fourth ventricle ; shading of central grey matter omitted as in Fig. 131. 



the results obtained by studying the degenerations following 

 upon injury to or removal of the several parts of the cortical 

 motor region, agree in marking out the paths taken by the 

 several constituents of the tract through the central white mat- 



