386 OLFACTORY NERVE. 



pathology, which shows that a single lamella may be injured or 

 atrophied, and at the same time be surrounded by others perfectly 

 sound. 



CRANIAL NERVES. 



There are nine pairs of cranial nerves. Taken in their order 

 from before, backwards, they are 



1st. Olfactory. 



2d. Optic. 



3d. Motores oculorum. 



4th. Pathetici (trochleares). 



5th. Trifacial (trigemini). 



6th. Abducentes. 



7 , ( Facial (portio dura), 



{ Auditory (portio mollis), 



( Glosso-pharyngeal, 

 8th. } Pneumogastric (vagus, par vagum). 



( Spinal accessory. 

 9th. Hypoglossal (lingual). 



Functionally or physiologically they are divided into four groups, 

 and in this order we shall examine them. 



Nerves of 



( 1st. Olfactory, 

 , \ 2d. Optic, 

 ( 7th. Auditory. 



C 3d. Motores oculorum, 



2. Motion . . . < 6th. Abducentes, 



( 9th. Hypoglossal. 



(4th. Patheticus, 



3. Respiration (Bell) . < 7th. Facial, 



( 8th. Glosso-pharyngeal. 

 Pneumogastric, 

 Spinal accessory. 



4. Spinal . .' - . 5th. Trifacial. 



NERVES OP SPECIAL SENSE. 



1st pair, OLFACTORY. This nerve rests against the under surface 

 of the anterior lobe of the brain, being lodged in the narrow interval 

 between two convolutions, and retained in its place by the arachnoid 

 membrane. 



It arises by three roots, 1. Internal, from the substantia perforata. 

 2. Middle, from a papilla of gray matter embedded in the anterior 



