EXAMINATION OF THE NERVOUS SYSTEM. 199 



for extending and turning the anterior limbs ; 4 controls the move- 

 ment of the posterior limbs; 5 the facial muscles ; and 6 the 

 lateral movement of the tail; 7 for retraction and adduction of 

 the anterior limbs; 8 for elevating the shoulders and stretching 

 the front legs (walking); 9 for dilating and contracting the orbic- 

 ularis palpebrarum and zygomaticus muscles. In the front of 9 we 

 also find the centre for the movements of the tongue. Between 

 the anterior and middle portion of 9 is for closing the jaw. Ou 

 irritating 9 we have a retraction and elevation of the corners of 

 the mouth. By irritating 6 the mouth is opened and the tongue 

 is moved, e, c, causes a retraction of the corners of the mouth; 

 c' lifts the corners of the mouth and half of the facial muscles as 

 far as the closing point of the eyelids. The middle e (on irritation) 

 opens the ey« and dilates the pupil. 



Any disease which becomes located in any portion of this cortico- 

 muscular brain centre and inflames or stops the power of these cen- 

 tres must lead to paralysis of the centre which it controls. We 

 therefore can locate any disturbance in the motor centres of the 

 brain by the paralysis which occurs in certain parts of the body. 

 A diseased condition of the covering of the brain, if not very 

 extensive, generally causes the paralysis of one part of the body, 

 as the single motor centres are separated and very distinct from 

 one another. Diseases of the brain, when they occur in the inner 

 surface between the capsules and the pyramids, where all the motor 

 fibres are close together, cause a more or less complete paralysis 

 of one side of the body. That is to say, a hemiplegia (affecting 

 one side of the brain) causes the paralysis of the muscles of the 

 other side of the body. For instance, if the disease is located 

 on the left side of the brain, the muscles of the right side become 

 paralyzed. In diseases of the spinal cord the muscles affected are 

 on the same side, except in the case of diseases of the cervical - 

 portion of the spine, when, as a rule, paralysis is seen in all the 

 extremities, and in disease of the lumbar region paralysis of t'le 

 posterior extremities is seen. We therefore summarize in a general 

 way that hemiplegia is usually a form of cerebral paralysis (of the 

 controlling centres); paraplegia indicates a diseased condition of 

 the spine; and monoplegia is due to a paralysis of the brain as 

 well as the spine. This description gives only the fundamental 

 theories on this subject. Concerning more precise details we 



