CHAPTER XIX 

 SPINAL NERVES MOTOR CRANIAL NERVES 



Spinal nerves Cranial nerves Motor oculi communis (third nerve) Physiological anat- 

 omy Properties and uses of the motor oculi communis Patheticus, or trochlearis 

 (fourth nerve) Physiological anatomy Properties and uses of the patheticus Motor 

 oculi externus, or abducens (sixth nerve) Physiological anatomy Properties and uses 

 of the motor oculi communis Nerve of mastication (the small, or motor root of the fifth 

 nerve) Physiological anatomy Properties and uses of the nerve of mastication 

 Facial, or nerve of expression (seventh nerve) Physiological anatomy General properties 

 of the facial Uses of branches of the facial given off within the aqueduct of Fallopius 

 Uses of the chorda tympani Influence of certain branches of the facial on the movements 

 of the palate and uvula Uses of the External branches of the facial Spinal accessory 

 (eleventh nerve) Physiological anatomy Properties and uses of the spinal accessory 

 Uses of the internal branch from the spinal accessory to the pneumogastric Influence of 

 the internal branch of the spinal accessory on deglutition Influence of the spinal acces- 

 sory on the heart Uses of the external, or muscular branches of the spinal accessory 

 Sublingual (twelfth nerve) Physiological anatomy Properties and uses of the sub- 

 lingual. 



WITH a knowledge of the general properties of the nerves belonging 

 to the cerebro-spinal system, it is easy to understand the uses of most 

 of the special nerves, simply from their anatomical relations. This is 

 especially true of the spinal nerves. These, in general terms, are dis- 

 tributed to the muscles of the trunk and extremities, to the sphincters 

 and the integument covering these parts, the posterior segment of the 

 head, and to certain mucous membranes. It is evident, therefore, that 

 an account of the exact office of each nervous branch would necessitate 

 a full description, not only of the nerves, but of the muscles of the body, 

 which is manifestly within the scope only of treatises on descriptive 

 anatomy. 



SPINAL NERVES 



There are thirty-one pairs of spinal nerves ; eight cervical, twelve 

 dorsal, five lumbar, five sacral and one coccygeal. Each nerve arises 

 from the spinal cord by an anterior (motor) and a posterior (sensory) 

 root, the posterior root being the larger and having a ganglion. Imme- 

 diately beyond the ganglion, the two roots unite into a single mixed 

 nerve, which passes out of the spinal canal by an intervertebral fora- 

 men. The nerve thus constituted is possessed of motor and sensory 

 properties. It divides outside of the spinal canal into two branches, 



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