Apraxias

Abstract

Anatomically and functionally voluntary movement has its basis on the motor unit and its connections with motor cortex through the pyramidal pathways. There is a direct proportion between fastness and precision of motor contraction and cortical representation of movement; most neurocortlcal density is found where fastest units are utilized In dexterity movements. Voluntary movement Is not a simple efferent system, rather it depends on a proprioceptive sensitive system that Informs brain about muscle activity and its length, tension and position, forming this way cinestesia or movement sensibility.

At the neuropsychological level movement is the result of a leaming process that starts as a reflex and gradually progresses toward a specific aim, mediated by inner language. This learning process goes through the steps of generalization and activation of most of the cortex and then localization In small neuronal groups with the final result of the motor stereotype or automatized  praxic. In this manner motor acts are structured as gestures.

Motor disorders are called apraxlas and are correlated with either left or right parietal lesions depending on patent’s dominancy and of his motor leamlng.