i6o HUMAN PHYSIOLOGY 



glands of the mouth. It, however, carries ingoing fibres from 

 the anterior two- thirds of the tongue. 



The VI. supplies the external rectus of the eye. 



The IV. supplies the superior oblique. The III. supplies 

 all the muscles of the eyes except those supplied by the VI. 

 and IV. 



The fibres coming from the nuclei of these cranial nerves 

 do not always pass out in the nerve itself. Thus, fibres from 

 the nucleus of the III. to the orbicularis oculi pass out in 

 the VIL, while fibres for the posterior belly of the digastric 

 which pass out in the VII. probably come from the nucleus 

 of the XII. 



4. Reflexes of the Medulla. 



The extensive series of synapses in the medulla form 

 arrangements by which various combined and co-ordinated 

 movements are controlled. Thus, part of the nucleus of the 

 vagus governs the movements of respiration, while other 

 parts preside over the slowing mechanism of the heart. To 

 these various reflex arrangements the name of centres has 

 been given. 



C. REGION OF PONS VAROLII. 



Outgoing Fibres. 1. The fibres to the face muscles cross 

 the middle line to become associated with the various nuclei 

 of the cranial nerves. For this reason a tumour in one side 

 of the pons may cause paralysis of the face muscles on one 

 side and of the muscles of the rest of the body on the 

 opposite side. 2. Fibres to the limbs and trunk run down 

 between the deep and superficial transverse fibres (Fig. 

 86, P.). 



Ingoing Fibres. The fillet fibres in the pons, instead of 

 running up on each side of the middle line, spread out into a 

 horizontal arrangement above the crossed fibres. 



D. CEREBELLUM. 



1. Structure. The cerebellum or lesser brain lies above 

 the fourth ventricle, and is joined to the cerebro-spinal axis 

 by three peduncles on each side. It consists of a central 



