AND PHYSIOLOGY. 



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ceed from the cerebro-spinal axis are given off in pairs on 

 opposite sides of the median line of the body. They are di- 

 vided into two sets ; those which are given off from the great 

 brain, little brain, and medulla oblongata, being called cranial 

 nerves, and those from the spinal cord, spinal nerves. 



581. Cranial Nerves —Many of the cranial nerves, and 

 all of the spinal nerves, arise by two roots, and soon form a 

 small protuberance, which is called a Ganglion or knot, in 

 which the fibers are confusedly mixed together, after which 

 they proceed in the same sheath to their destination. 



582. Of the cranial nerves there are twelve pairs, named 

 as follows : 



First pair. , 

 Second " . , 

 Third " .. 

 Fourth " . 

 Fifth " .. 

 Sixth " .. 



. . Olfactory. 

 . .Optic. 



, .Motores Oculorum. 

 . . Trochleares. 

 , .Trifacial. 

 , .Abducentes. 



Seventh pair.. Facial. 

 Eighth " ..Auditory. 

 Ninth " . .Glosso- Pharyngeal. 

 Tenth " . .Par Yagi. 

 Eleventh " . .Spinal Accessory. 

 Twelfth " \ .Lingual. 



583. Olfactory, — The olfactory nerves arise from the an- 

 Fig. 310. 



A View of the First Pair, or Olfactory, with the Nasal Branches of the Fifth. 1, From 

 tal Sinus. 2, Sphenoidal Sinus. 3, Hard Palate. 4, Bulb of the Olfactory Nerve. 5, 

 Branches of the Olfactory on the Superior and Middle Turbinated Bones. 6, Spheno- 

 palatine Nerves from the Second of the Fifth. 7, Internal Nasal Nerve from the First 

 of the Fifth. 8, Branches of Seven, to Schneiderian Membrane. 9, Ganglion of Cloquet 

 in the foramen incixivium, 10, Anastomosis on the Inferior Turbinated Bone of the 

 Branches of the Fifth Pair. 



"What are the two principal groups of nerves ? 581. How many roots do most of the 

 nerves have ? 582. How many pairs of cranial nerves, and what are their names ? 



