570 TEXT-BOOK OF PHYSIOLOGY 



The cells of the post- genicul urn give origin to axons which pass upward, 

 forward and outward, enter the internal capsule, and pass by way of the 

 auditory tract to the cortex of the temporo-sphenoidal region of the cerebrum. 

 Many of the fibers of the lateral fillet, a portion of the auditory tract, termi- 

 nate in brush-like expansions around these same cells. There is thus es- 

 tablished a connected pathway between the cochlea and the temporo-sphe- 

 noidal cortex. The cells of the temporal cortex, however, send axons in the 

 reverse direction by way of the auditory tract to the cells of the post-genie ulum. 

 There is thus established a double communication between the occipital 

 and temporal regions of the cerebral cortex, and the pre-geniculum and post- 

 geniculum bodies respectively. 



THE BASAL GANGLIA: THE CORPORA STRIATA AND OPTIC 



THALAMI 



The basal ganglia are collections of ganglionic matter, situated at the 

 base of the cerebrum along the course of the nerve-fibers that pass to and 



236. CORPORA STRIATA, OPTIC THALAMI, CORPORA QUADRIGEMINA, CEREBELLUM AND 



ASSOCIATED STRUCTURES, i, Corpora quadrigemina; 2, valve of Vieussens; 3, pre-peduncle; 



4, upper part of medi-peduncle; 5, upper part of crus; 6, lateral fillet; 7, band of Reil; 8 post- 



mra; 9, frenulum; 10, gray matter of valve of Vieussens; u, medi-commissure; 12, pre-com- 



ire; 13 14, center of cerebellum; 15, post-commissure; 16, peduncles of the pineal gland; 17, 



ical gland; 18, 19, posterior and anterior tubercles of the thalamus; 20, teniasemicircularis; 21, 



the corpus striatum; 22, fornicolumn; 23, corpus striatum; 24, septum lucidum. 



from its cortical expansion. Among these ganglia the more important are 

 e corpora striata and the optic thalami. They are made visible upon 

 removal of the cerebrum. The general relations of these ganglia are shown 

 m Fig. 236. 



The corpus striatum, the more anterior of the two, is an ovoid 



