THE EXAMINATION OF A SICK HORSE. 23 



THE EXAMINATION OF THE NERVOUS SYSTEM. 



The great brain, or cerebrum, is the seat of intelligence, and it con- 

 tains the centers that control motidii in many parts of the body. 

 The front portion of the brain is believed to be the region that is most 

 important in governing the intelligence. The central and posterior 

 portions of the cerebrum contain the centers for the voluntary motions 

 of the face and of the front and hind legs. The growth of a tumor or 

 an inflammatory change in the region of a center governing the 

 , motion of a certain part of the body has the effect of disturbing 

 motion in that part by causing excessive contraction known as cramps, 

 or inability of the muscles to contract,- constituting the condition 

 known as paralysis. The nerve paths from the cerebrum, and hence 

 from these centers to the spinal cord and thence to the muscles, pass 

 beneath the small brain, or the cerebellum, and through the medulla 

 oblongata to the spinal cord. Interference with these paths has the 

 effect of disturbing motion of the parts reached by them. If all of 

 the paths on one side are interfered with, the result is paralysis of one 

 side of the body. 



The small brain, or cerebellum, governs the regularity, or coordi- 

 nation, of movements. Disturbances of the cerebellum cause a totter- 

 ing, uncertain gait. In the medulla oblongata, which lies between the 

 spinal cord and the cerebellum, are the centers governing the circula- 

 tion and breathing. 



The spinal cord carries sensory messages to the brain and motor 

 impressions from the brain. The anterior portions of the cord con- 

 tain the motor paths, and the posterior portions of the cord contain 

 the sensory paths. 



Paralysis of a single member or a single group of muscles is known 

 as monoplegia and results from injury to the motor center or to a 

 nerve trunk leading to the part that is involved. Paralysis of one- 

 half of the body is known as hemiplegia and results from destruction 

 or severe disturbances of the cerebral hemisphere of the opposite side 

 of the body or from interference with nerve paths between the cere- 

 bellum, or small brain, and the spinal cord. Paralysis of the poste- 

 rior half of the body is known as paraplegia and results from de- 

 rangement of the spinal cord. If the cord is pressed upon, cut, or 

 injured, messages can not be transmitted beyond that point, and so 

 the posterior part becomes paralyzed. This is seen when the back is 

 fractured. 



Abnormal mental excitement may be due to congestion of the brain 

 or to inflammation. The animal so afflicted becomes vicious, pays no 

 attention to commands, cries, runs about in a circle, stamps with the 

 feet, strikes, kicks, etc. This condition is usually followed by a dull, 

 stupid state, in which the animal stands with his head down, dull and 



