LECTURES ON THE CENTRAL NERVOUS SYSTEM. 



The corona radiata, therefore, consists of fibres which pass 

 to the thalamus, and of fibres which pass to deeper regions. 



Fibres pass to the thalamus from almost all the surface of 

 the cortex, and not in a few bundles merely, as is shown in the 

 following diagiam. They unite near the thalamus to form thick 

 strands, which are called the pedicles (stilus) of the thalamus. 

 Among fibres passing farther caudad arc: 

 1. Fibres from the cortex of the central convolutions and the 

 paracentral lobule; that is, from the motor region of the brain to 

 the nuclei of the motor nerves in the brain and the spinal cord 



(pyramidal tract). 



2. The speech-tract, 

 to the nuclei of the 

 nerves in the oblongata 

 which have to do with 

 speech. Its origin in the 

 cortex of the third frontal 

 convolution, its course; 

 through the white sub- 

 stance to the outside of 

 the tail of the nucleus 

 caudatus, and its termi- 

 nation in the nuclei 

 above mentioned, have 

 all been inferred from carefully-observed clinical cases, verified 

 by autopsies. It has not yet been actually demonstrated by 

 dissection. The speech-tract in passing over the anterior portion 

 of the nucleus lentiformis lies very near the central hypoglossal 

 tract. 



3. Bundles from the cortex of the frontal lobe to the pons 

 or, rather, to its ganglion-cells (anterior cortical tract to the pons). 

 They pass, in all probability, from the pons into the cerebellum. 



4. Bundles from the cortex of the occipital and temporal 

 lobes, also ending, apparently, in the ganglion-cells of the pons 

 (posterior cortical tract to the pons). 



FIG. 43. 



Diagram of the fibres of the corona rarliatn, espe- 

 cially the coronal fibres to the thalamus. U.S., infer. or 

 pedicle. 



Sehhuyel, Thalarnus. 



