The neurons supplying skeletal muscles have their cell bodies located in the ventral horn of the spinal cord. The neurons which are of the Aα type (hence called the α-motoneuron) receive and integrate inputs from various parts of the brain as well from sensory receptors. Hence, they serve as the final common pathway to the muscle.
In general, the final common pathway receives two types of inputs:
(1) Inputs through sensory nerves. These come from receptors in the muscle (the muscle spindle), the tendon (Golgi tendon organ) and skin (nociceptors). As these sensory neurons relay on the a-motoneuron, they constitute a reflex arc and subserve important spinal reflexes like the stretch reflex, negative stretch reflex and the withdrawal reflex.
(2) Descending motor pathways from supraspinal centers. These descend from various parts of the brain like the cerebral cortex, basal ganglia, cerebellum and descending reticular formation.