276 



THE CAT. 



[CHAP. ix. 



16. Here it may be well to present a preliminary SUMMARY of 

 the nerves of the encephalon with respect to their functions, although 

 the functions of the nervous system and of its main divisions will he 

 described more fully later. 



The twelve nerves just enumerated may be divided into three 

 categories : (A.) Those which minister to special sense ; (B.) those 

 which arc motor, and (C.) those which minister both to common 

 sensation and to motion. 



The nerves which minister to speeial sensation are the first, 

 second, eighth, the gustatory branch of the fifth, and the tongue 

 branches of the glosso-pharyngeal. 



The third, fourth, sixth, seventh, and twelfth, are motor nerves. 

 The fifth, glosso-pharyngeal, pneumogastric, and spinal accessory 

 nerves are all both motor and sensory, though the glosso-pharyngeal 

 is mainly sensory. 



17. The SPINAL NERVES arise systematically, in pairs, from 

 opposite sides of the spinal marrow. They are related in number to 

 the divisions of the axial skeleton, or vertebrae, and (as has been 

 said in describing that skeleton) they pass out of the neural canal 

 in the intervals between the neural arches. They are severally 

 reckoned as cervical, dorsal, lumbar, sacral, or caudal, according to 

 their proximity to similarly named vertebra?, each nerve taking the 

 name of that vertebra which forms the anterior boundary of its place 

 of exit. Thus, inasmuch as one spinal nerve comes out above (in 

 front of) the atlas, there are eight cervical nerves, thirteen dorsal, 

 seven lumbar, and three sacral, while the rest are caudal. 



The spinal nerves each arise by two roots, and each, after leaving 

 the neural vertebral canal, divides into two conspicuous branches 

 (one dorsal and the other ventral), besides sending a twig to the 

 sympathetic. 



Of these two series of conspicuous branches it is the ventral series 

 which constitutes the nerves of the limbs, while, in the interval 

 between the limbs, the ventral branches pass round in the body wall 

 the thoracic ones in the intercostal spaces, and the abdominal ones 

 between the internal oblique and trans versalis muscles, as will be 

 shortly described. 



The ROOTS by which each spinal nerve arises are (as has been 

 said) two in number: one anterior (ventral), and the other posterior 

 (dorsal), and each is made up of a number of small bundles (funi- 

 citli) of nerve-fibres. 



The funiculi of the posterior (dorsal) root come forth from the 

 posterior lateral furrow. They are larger and more numerous than 

 are the funiculi of the anterior root. Within the substance of the cord 

 the fibres of the posterior or dorsal root of each nerve may be traced 

 diverging in three directions, namely, postaxially, or away from the 

 brain, preaxially, or towards the brain, and transversely across. The 

 first pass along the grey matter to the anterior cornu and anterior 

 white columns. The second advance through the grey matter to the 

 posterior columns. The third (transverse fibres) enter the posterior 



