20 



THE NERVOUS SYSTEM 



with the auditory tract, and the grey matter which it contains 

 constitutes one of the lower auditory centres. 



The third (pculo-motor) &\\& fourth (trochlear) cerebral nerves 

 emerge from the surface of the mid-brain. The former 

 appears on the anterior aspect, but the latter leaves the dorsal 

 aspect just below the inferior pair of corpora quadrigemina. 



The Pons is interposed between the mid-brain above and 

 the medulla oblongata below. Laterally, it is connected to 



FIG. 12. The Anterior Aspect of the Brain-Stem. 



1. Pons. 



2. Trigeminal nerve. 



3. Brachium pontis. 



4. Medulla oblongata. 



5. Pyramid. 



6. Olive. 



7. Superficial arcuate fibres. 



8. Restiform body. 



9. Mid-brain. 



to. Lateral geniculate body. 



the cerebellar hemispheres by the brachia pontis (middle 

 cerebellar peduncles). Its anterior surface bulges forwards and 



