NERVE 



163 



The fibres of the posterior division of each optic tract ends 

 in synapses with neurons in the anterior coUiculus of the 

 tectum, and the fibres of these neurons pass downwards and 

 control the oculo-motor mechanism already described (fig. 81). 



The fibres of the anterior division make synapses with 

 other neurons in the external geniculate body and pulvinar 



.'^E 



{opTT,^ : 



« ' > \ 



(OcM) ! 



Dec. L. 



Fig. 81. — The Connections of the Retinje with the Central Nervous System. 

 R, retinae; Ch., chiasma leading to optic tract; Op.Th., optic 

 thalamus; A.G.Q., anterior coUiculus of the tectum ; Oc.M., oculo- 

 motor mechanism (fig. 80) ; Occ.L., occipital lobe of the cerebrum. 



of the thalamus, and in the thalamus visual impressions 

 become associated and integrated with those of other 

 receptors — touch, hearing, etc. (fig. 81, Op.Th.; see also 

 fig. 50, p. 113). 



From the thalamus a great band of fibres, which early 

 get their white sheath, sweeps outwards and backwards to 

 cortex on the internal aspect of the occipital lobe. 



