This document summarizes the spinal control of movement. It discusses how motor neurons innervate skeletal muscles and are wired into reflex loops in the spinal cord. The spinal cord also contains central pattern generators that provide rhythmic patterns for activities like walking. Skeletal muscle contraction is enabled by the sliding filament model where actin and myosin interact through a cross-bridge cycle powered by ATP hydrolysis. Motor neurons and calcium signaling control muscle contraction and relaxation.