364 



ANATOMY IN A NUTSHELL. 



or pes and has motor fibres in it. The posterior portion is the tegmental por- 

 tion and has sensory fibres in it. 



The Restiform body or inferior peduncles of the cerebellum receives its 

 fibres from four main sources (1) from the nucleus gracilis et cuneatus of the 

 same side. (2) from nucleus gracilis et cuneatus of opposite side, (3) from the 

 lateral column of the cord through the direct cerebellar tract, (4) from the 

 nucleus of the olivary body of the opposite side. 



PLATE CLXXXIV. 





A Sagittal Section ok the Brain. 



The area where the cranial nerves leave the brain substance is called the 

 Si perficial ORIGIN. The group of cells from which the fibers spring or in which 

 they end is the deep origin. (Plate CLXXXVII). 



Rule. — The deep origin of all the cranial nerves, except the first and sec- 

 ond ;ind a part of the eleventh, is in the floor of the aqueduct of Sylvius or 

 in the floor of the fourth ventriclk. The third and fourth have their deep 

 origin in the aqueduct of Sylvius. The fifth, sixth, seventh, eighth, ninth, 

 tenth, pari of the eleveth, and twelfth have their deep origin in the floor of the 

 fourth ventricle. • 



Definition for centre. — (1) Any ganglion or plexus giving off nerves 

 which control function. (2) Any GROUP of ganglion tells which has a stim- 

 ulating or inhibitory office. (3) It is a group of GANGLION CELLS closely con- 

 nected with one another and acting together in the performance of some func- 

 tion, as the cerebral centers, psychical centers; respiratory or vaso-rnotor cen- 

 ter-. 



The first and second cranial nerves are processes of the brain and therefore 

 have neither superficial nor deep origin. We say there are twelve pairs of 

 cranial nerves; it would be better to say twelve sets for in the first or olfactory 

 nerves there are twenty or thirty nerves. The first nerve is one of special sense, 

 thai of smell. The primary center for smell is in the olfactory lobe. (Plate 



