COMPOSITION AXD CENTRAL CONNECTIONS OF CRANIAL NERVES 865 



either pass over or through the lateral geniculate body to the pulvinar of the 

 thalamus. These end-stations are often called the primary visual centers. 



The lateral geniculate body consists of medium-sized pigme'nted nerve cells 

 arranged in several layers by the penetrating fibers of the optic tract. Their axons 

 pass upward beneath the longer fibers of the optic tract, the taenia semicircularis, 

 the caudate nucleus and the posterior horn of the lateral ventricle where they join 

 the optic radiation of Gratiolet. They pass backward and medially to terminate 

 in the visuo-sensory cortex in the immediate neighborhood of the calcarine fissure 



Optic nerve 

 Crossed fibers 

 Uncrossed fibers 



Optic chiasma 



Optic tract 

 Commissure of Oudden 



Pulvinar 



Lateral geniculate body 

 Superior colliculus 

 Medial geniculate body 



Nucleus of oculomotor nerve 

 Nucleus of trochlear nerve 

 Nucleus of abducent nerve 



f 



Cortex of occipital lobes 

 FIG. 763. Scheme showing central connections of the optic nerves and optic tracts. 



of the occipital lobe. This center is connected with the one in the opposite side by 

 commissural fibers which course in the optic radiation and the splenium of the corpus 

 callosum. Association fibers connect it with other regions of the cortex of the same 

 side. 



The region of the pulvinar in which optic tract fibers terminate resembles in 

 ructure the lateral geniculate body. Its axons also have a similar course though 

 in a somewhat more dorsal plane. 



The superior colliculus receives fibers from the optic tract through the superior 

 brachium. Some enter by the superficial white layer (stratum zonale), others 

 appear to dip down into the gray cap (stratum cinereum) while others probably 

 55 



