SCHEME OF THE CENTEAL NEKVOUS SYSTEM. 



6 5 I 



from the 3rd ventricle through the aqueduct of Sylvius, and the medulla oblongata, to the 

 lowest part of the grey matter of the spinal cord. It lines the inner surface of the medullary 

 tube. It is the second stage in the course of the fibres extending from the basal ganglia to the 



R 



Fig.,461. 



I, Scheme of the brain. C, C, cortex cerebri; C.s, corpus striatum; N.Z, nucleus lenti- 

 cularis ; T.o, optic thalamus ; v, corpora quadrigemina ; P, pedunculus cerebri ; H, 

 tegmentum ; and p, crusta ; 1, 1, corona radiata of the corpus striatum ; 2, 2, of the lenti- 

 cular nucleus ; 3, 3, of the optic thalamus ; 4, 4, of the corpora quadrigemina ; 5, pyramidal 

 fibres from the cortex cerebri (Flechsig) ; 6, 6, fibres from the corpora quadrigemina to the 

 tegmentum ; ra, further course of these fibres ; 8, 8, fibres from the corpus striatum and 

 lenticular nucleus to the crusta of the pedunculus cerebri ; M, further course of these ; S, S, 

 course of the sensory fibres ; R, transverse section of the spinal cord ; v.W, anterior, and 

 . h.*W, posterior roots; a, a, association system of fibres ; c, c, commissural fibres. II, 

 Transverse section through the posterior pair of the corpora quadrigemina and the pedunculi 

 cerebri of man. p, crusta of the peduncle ; s, substantia nigra ; v, corpora quadrigemina, 

 with a section of the aqueduct. Ill, The same of the dog ; IV, of an ape ; V, of the 

 guinea-pig. [See p. 650.] 



central tubular grey matter. The fibres of this system must obviously vary greatly in length ; 



some fibres end in the central grey matter above the medulla oblongata, e.g., in the oculomotor 



nucleus, while others reach to the level of the last spinal nerves. In the central grey matter, 



