ZOOLOGY. 



hemispheres, and a mesial portion connecting them together. 

 On the surface of the cerebellum there are no convolutions, 

 but the margins of lamin;i: or plates, of which the cerebellum 



a f b c 



r> 



7 9 10 11 6 e 



Fig. 56. Section of the Brain, Cerebellum, Pons, and Medulla 

 Oblongata.* 



* Vertical section of the cerebrum, cerebellum, pons Varolii, and medulla 

 oblongata ; a, anterior lobe of the brain ; b, middle lobe ; c, posterior lobe ; 

 d, cerebellum; e, medulla spinalis;/, section of the corpus callosum. The 

 lateral ventricles of the brain are situated on either side of the corpus callo- 

 sum, which assists in forming their upper wall, g, optic lobes : 1, olfactory 

 nerves ; 2, the eyeball, from which may De traced the optic nerve as far as the 

 optic thalami or lobes. Close to this is the nerve of the third pair. 4, the 

 fourth pair, distributed, like the third, to the muscles of the eyes ; 5, superior 

 maxillary branch of the fifth pair; 5', ophthalmic branch of the same pair of 

 .">", inferior maxillary branch of the same pair of nerves ; 6, sixth pair, 

 proceeding to the abducentes muscle ; 7, facial nerve : under the origin of 

 this nerve may be seen a portion of the acoustic : 9, nerve called glosso- 

 pharyngeal; 10, pneumogastric nerve; close to it is, 12, the spinal acces- 

 sory ; these three nerves, the glosso-pharyngeal, pneumogastric, and spinal 

 accessory, are by some reckoned as one pair ; 11, the ninth pair of some, 

 and the eleventh of others, called also hypoglossal ; 14 and 15, cervical nerves . 





