196 PHYSIOLOGY OF CENTRAL NERVOUS SYSTEM. 



late body, but some pass also to the optic thalamus (pulvinar) and 

 some to the anterior colliculus of the corpora quadrigemina. These 

 locations, therefore, particularly the external geniculates, must be 

 considered as the primary optic centers. From these points the path 

 is continued toward the cortex by new neurons whose axons consti- 

 tute a special bundle, the optic radiation, lying in the posterior limb 

 of the internal capsule (see Fig. 76, D). A schema representing 



Occipital lobe. 



Optic radiation. 

 Superior colliculus. ( 



Lateral or external geniculate. 

 Optic thalamus. 



Optic tract. 



Optic chiasm. 

 Optic nerve. 

 c- Retina. 



Fie 86 -Diagram to indicate the general course of the fibers of the. optic nerves and the 

 bilateral connection between cortex and retina. 



this course of 'the optic fibers is given in the accompanying diagram 

 (Fig "8Q). According to this schema, the general relations of each 

 occipital' lobe to the retinas of the two eyes is such that the right 

 occipital cortex represents the cortical center for the two right 

 halves of the retinas, while the left occipital lobe is the center for 

 the two left halves of each retina, a relation that agrees completely 

 with the results of experimental physiology and clinical studies. 

 In addition to the fibers described, which may be regarded as the 

 visual fibers proper, there are other fibers in the optic tracts and 



