492 



THE ANATOMY OF THE HORSE 



controlling the organs of special sense, situated at tlie hase of the 

 brain. 4tli. The cereljelluni, -svliic-li seems speci- 

 ally intended to coniLine and balance tlie several 

 muscular actions of the body. 5th. The cerebrum, 

 Avhich is the scat of intelligence and will. Gth, 

 The sympathetic system of ganglia, which speci- 

 ally controls the vital organs of circulation, diges- 

 tion, and depuration. The first five divisions are 

 generally included under the head of the nervous 

 sj'stem of animal life, the last being considered 

 to be peculiar to organic life. The diagram on 

 the preceding page will show at one view the 

 chief component parts of the two systems. 



THE SPINAL CORD 



<^ 



The spinal cord ma}' be considered to be the 

 primaiy division of the nervous S3'stem, because 

 it represents the lowest development of this organ 

 in the animal kingdom. But instead of consist- 

 ing of a series of locomotive ganglia, as in the 

 articulata, it is here found in the shape of two 

 long masses of grey matter, covered with white 

 fibres, which serve to communicate between the 

 several parts of which it is comjposed. 



Opposite each joint, between the vertebrae, a 

 nerve is given oflF, which passes out in the foramen 

 specially contrived for its exit, and thence goes 

 on to its destination. Each of these nerves has 

 two distinct origins ; one from the uj^per part of 

 the grey central matter (the sensitive root), the 

 other from its inferior surface, which is the motor 

 portion. The superior has an accession of grey 

 matter around it, soon after the union of its 

 nervelets, called its ganglion, beyond which the 

 two divisions unite to form a large nerve, which 

 soon begins to subdivide again for supplying the 

 several parts of the bod}'. The terminating 

 branches reunite in loops, so that these nerves 

 may he considered to form a complete circle, 

 those of sensation receiving impressions from the 

 parts on which they are distributed, and conveying 

 them to the central ganglion, while the motor 

 nerves cause the muscles which they supply to 



j-ic. 82.— SriNAL Cor.D uemovf.d from its Canal. 



o. n. a. Rofits of the siiinalnpn'PS. 



b. h. The (ilaineits go'iig to unite to form each of tliesft nervea, 



c. c. Clear sj.accs bttwi'i'n tlu' roots of the nerves. 



