646 PHYSIOLOGY OF THE CEREBRUM 



The disturbance in function which makes its appearance after a lesion 

 in the motor region is as a rule greater at first than later, owing no doubt 

 to some interference with the circulation and to shock. After this remote 

 effect of the lesion has passed away, as it does within a few days, the primary 

 loss of function conies more prominently to the front. Movements of parts 

 connected with the cortical area destroyed can no longer be executed as be- 

 fore, and in adults they are either finally lost or are always thereafter executed 

 with abnormal weakness. It is to be observed, however, that even such move- 

 ments can continue to be performed in association with others. When, for 

 example, the cortical field for the extension of the right thumb is entirely 

 destroyed, the ability to make sure, strong and precise extensor and abductor 

 movements with that thumb is lost; but in connection with the fingers it can 

 still be used very skillfully in various kinds of complicated movements (v. 

 Monakow). 



The influence of the cerebral cortex in man on the movements of his body 

 appears very clearly from the following observation. A patient was born with 

 hemiplegia on the left side. When he was taken to the hospital at the age of 

 twenty-nine, his left limbs were very much stunted. He could walk with the 

 help of crutches, but could not lift his left leg from the floor. On opening the 

 skull it was found that the whole right hemisphere of the cerebrum had disap- 

 peared and was replaced by fluid (L'Allemand). 



In considering the recovery of the muscular functions., we must bear in 

 mind that the extremities are represented not only on the convex surface of 

 the cerebrum, but also on the medial side ; also that according to observations 

 on monkeys, it is only the coarser movements that are dependent on the latter 

 region. When therefore the lesion ojccurs only on the outer convex portion 

 of the cortex, it is still possible for the medial portion to direct the coarser 

 movements of the extremities. 



With lesions acquired very early in life, a very considerable degree of resti- 

 tution is possible. In one case of defect of the two right central convolutions 

 observed by v. Monakow, the patient at ten was able to use his left arm 

 (atrophied though it was) in the proper way, in all possible sorts of manipula- 

 tions e. g., in playing ball ; some considerable clumsiness was apparent how- 

 ever in the use of the left hand and fingers. 



After a cortical lesion contractures i. e., abnormal, persistent contrac- 

 tions gradually make their appearance in the muscles of the paralyzed limbs. 

 Different hypotheses have been put forward concerning the cause of these, 

 but their discussion here would lead us too far afield. It must suffice to 

 observe only that, according to H. Munk, contractures in the monkey can 

 be prevented, if, as soon as the limbs affected begin to offer some resistance 

 to passive movements, they be stretched as far as possible for a few minutes 

 every day. The contractures are brought on by the loss of motility. Hence 

 they do not occur in the case of animals which move about spontaneously 

 after the operation, for the paralyzed extremity can be used in connection 

 with the other extremities in walking even though isolated movements can- 

 not be executed. 



