422 



PHYSIOLOGY 



^T" LIMB 

 TV CAPSULE 



latter nucleus and partly in the cortex of the temporal lobe and of the insula 

 or island of Reil. 



(2) THE FILLET SYSTEM OF FIBRES. This great mass of ascending fibres 

 has been already described (op. Fig. 197) as gathering up the impulses from 

 the different sensory nerves of the cerebro-spinal system and terminating 

 in the thalamus and subthalamic region. 



(3) THE SUPERIOR CERE- 



BELLAR PEDUNCLE. These 



fibres, from the central 

 ganglia of the cerebellum, 

 terminate for the most part 

 in the thalamus and sub- 

 thalamic region. It is pos- 

 sible that some of them may 

 pass through the hinder end 

 of the internal capsule, with- 

 out interruption in the thal- 

 amus, to end in the Rolandic 

 area. 



(4) THE OPTIC RADIATION. 

 These diverging fibres in the 

 back part of the corona- 

 radiata are mixed up with 

 fibres which are partly corti- 

 cifugal. The corticipetal 

 fibres arise in the pulvinar 

 and the external geniculate 

 body and end in the occipital 

 cortex. 



(5) THE AUDITORY RADIA- 



T>Tr\ 



fibres of cortex. 



CORP: GEN : INT. 

 SUP QUADS BODY 



TEMPORO-PONTINE 

 TRACT 



FlQ. 214. 



LOBL 



Schema of projection 

 (CUNNINGHAM.) 



TION. These fibres consist of 

 the axons of cells situated in 

 the internal geniculate body. 



They pass through the posterior limb of the internal capsule under the 



lenticular nucleus to end in the temporal lobe. 



B. THE EFFERENT PROJECTION FIBRES. 



( 1 ) THE PYRAMIDAL TRACT. This is composed of fibres which arise from 

 the large Betz cells in the ascending frontal convolution, the ' motor area.' 

 They pass through the corona radiata into the internal capsule, whore they 

 occupy the genu and the anterior two- thirds of the posterior limb. Hence 

 they pass into the crusta, where they occupy the middle two-fifths of this 

 structure, and are continued as the pyramids of the pons and medull;i t<> 

 the upper part of the spinal cord, where most of them decussate to the other 

 side to form the crossed pyramidal tracts. Some of the fibres do not en sa 



