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MAMMALIA— PHYSIOLOGY 



Table of Cerebral Nerves and Their Components in Mammals — Continued 



In the I, II, III, IV, VI, and VIII nerves the organs of special sense are supplied, 

 while the V, VII, IX, X, and XI cerebral nerves have visceral functions predominating. 



Consult Johnston's Comparative Neurology and article by C. J. Herrick in Refer- 

 ence Handbook of Medical Sciences, entitled the Cranial Nerves. 



The bodies of Purkinje cells are surrounded by the basket ter- 

 minals of the stellate cells of the molecular layers, while their proto- 

 plasmic processes are in contact with the efferent fibers that arise 

 from more distant portions of the nervous system. 



Medulla Oblongata. — The medulla oblongata controlling heart 

 beat and respiration, the enlarged anterior portion of the spinal cord, 

 sends off the cerebral nerves from the fifth to the twelfth inclusive. 

 It receives columns of fibers originating in the spinal cord and may 

 be considered a great switch station for impulses passing up and 

 down the cord. 



Spinal Cord. — In all vertebrates having well-developed limbs 

 the two regions of the spinal cord with which the nerves of the limbs 

 are connected are somewhat thicker than the rest of the cord and are 

 known as the thoracic and lumbar enlargements. Each of the 

 spinal nerves has a ventral anterior root and a dorsal posterior root 

 with spinal ganglia, containing nerve cells and fibers which are 

 usually afferent., conveying impulses from the parts and organs of 

 the body to the central nervous system. The vetttral root is not 

 ganglionated and its fibers are efferent, conveying impulses from the 

 neuron outward. The cranial nerves are twelve in number on each 

 side in reptiles, birds and mammals. Only the trigeminal or fifth 

 present a double-rooted arrangement similar to a spinal nerve. 

 Several however have ganglia comparable to those of the dorsal 

 roots of the spinal nerves. Besides the fifth or trigeminal these 



