The primary motor cortex is a region of the frontal lobe that is involved with voluntary movement. It generates signals to direct the movement of the body and sends most electrical impulses coming out of the motor cortex. The primary motor cortex is located in the precentral gyrus, which is just anterior to the central sulcus. It contains large neurons known as Betz cells, which send long axons down the spinal cord to synapse onto the interneuron circuitry of the spinal cord and also directly onto the alpha motor neurons in the spinal cord which connect to the muscles. The primary motor cortex encodes the direction and force of movement, but it does not generally control individual muscles directly. Instead, it controls individual movements or sequences of movements that require the activity of multiple muscle groups. The primary motor cortex works in association with other motor areas, including the premotor cortex, the supplementary motor area, posterior parietal cortex, and several subcortical brain regions, to plan and execute voluntary movements.