1. Commands (Idea for a voluntary action) are generated in the cerebral cortex (for e.g. left hand has to be lifted).
2. These impulses are then sent to the basal ganglia and the lateral cerebellum where further planning and organization of the movements takes place, (i.e First left hand thumb will be lifted followed by 2, 3, 4 and 5 finger).
3. The basal ganglia and the lateral portions of the cerebellum are part of a feedback circuit to the premotor and motor cortex that is concerned with planning and organizing voluntary movement. The basal ganglia and cerebellum both funnel information’s to the premotor and motor cortex by way of the thalamus.
4. These impulses then reach the motor and premotor cortex which actually signals the initiation of movements. This area controls all the skeletal muscles of the body. These signals (nerve impulses) then travel from the motor cortex via neuronal pathways in the brain and the spinal cord, (through CS and CB tracts) to reach the anterior horn cells located adjacent to the spinal cord.
From here the spinal nerves travel through the body tissues to reach the muscles and innervate them. The impulses on reaching the muscles fibres contracts them bringing about the desired voluntary movement
5. Simultaneously these impulses are sent to the intermediate cerebellum so that the movements occur in a smooth and coordinated fashion.
6. The ventral corticospinal tract and the medial descending paths from the brain stem (the tectospinal, reticulospinal, and vestibulospinal tracts) are concerned with adjustments of proximal muscles and posture, whereas the lateral corticospinal tract and the rubrospinal tract are concerned with distal limb muscles and, particularly in the case of the lateral corticospinal tract, with skilled voluntary movements.