THE OPTIC NERVE 



optic tract of the same side. Each optic tract contains, there- 

 fore, fibres arising from the temporal half of the retina of its 

 own side and fibres arising from the nasal half of the retina 

 of the opposite side (Fig. 28). 



The optic tract passes backwards and laterally round the 

 lateral side of the cerebral peduncle and its fibres terminate in 

 the lower visual centres These consist of (i) The pulvinar 

 of the thalamus (p. 29) ; (2) the lateral geniculate body (p. 

 30); and (3) the superior corpora quadrigemina (p. 18). 



Optic tract 



Lateral geniculate bod y * 



Medial geniculate body 

 Pulvinar 



Corpora quadrigemina.- 



~ Mid-brain 



- Corpus mamillare 



Trigeminal nerve 



. Pons 



. Facial nerve 



FIG. 29. The Lateral Aspect of the Brain-Stem. 



From the cells in the lower visual centres there arise 

 new fibres which at once enter the retro-lenticular part of 

 the posterior limb of the internal capsule, where they are 

 related anteriorly to the acoustic and other sensory fibres. 

 They then pass backwards into the occipital lobe and 

 terminate in the cortex on its lateral and medial aspects. 

 Those fibres which arise in the lower quadrant of the retina 

 are connected with the upper portion of the occipital cortex, 

 while those from the upper quadrant of the retina are 

 connected with the lower portion (p. 13). The lower visual 



