2.2 Basic Motor Pathway. Examination of Motor Functions. Lesions of Pyramidal Tract at Multiple Levels
All movements are effected by contractions of striated muscles through the control of the NS. Thus motor activity is the result of integral activity of the NS. They distinguish voluntary movement which is realized with the help of the cerebral cortex, and involuntary, which is constructed as simple and complex reflex acts. Voluntary movements are controlled by the pyramidal tract, involuntary – the extrapyramidal system, the reticular formation and the segmental apparatus of the spinal cord. By means of our motor system we move our bodies in space. The motor system controls the timing, direction, amplitude, and force of movement.
The examination of motor functions includes the determination of muscle power, an evaluation of muscle tone and muscle bulk and the observation of abnormalities of movement.
The motor impulses for voluntary movement are mainly generated in the precentral gyrus of the frontal lobe (first motor neuron). They pass in the long fiber pathways (mainly the corticonuclear and corticospinal tracts (pyramidal pathway) through the brainstem and down the spinal cord to the anterior horn, where they make synaptic contact with the second motor neuron—usually by way of one or more intervening interneurons.
