Precentral gyrus

Recommended video: Introduction to the brain [15:09]

Basic anatomy and function of the brain.

The precentral gyrus is the elevated ridge of brain tissue located on the dorsolateral and lateral surfaces of the frontal lobe of each cerebral hemisphere, with its upper aspect also extending onto the medial surface. The precentral gyrus is bordered anteriorly by the precentral sulcus, posteriorly by the central sulcus, and inferiorly by the lateral sulcus.

The primary motor (somatic) cortex (Brodmann's area 4, M1) is contained within the precentral gyrus of each hemisphere. It contains large neurons called pyramidal cells that project their axons down to the spinal cord to form the pyramidal (corticospinal and corticonuclear) tracts which allow us voluntary movement of the body's skeletal muscles. Each primary motor cortex controls the muscles on the contralateral (opposite) side of the body. The topographic representation of motor processing of different body parts within the precentral gyrus is known as the motor homunculus, which shows that there is a disproportionate representation of how much of the cortex is devoted to different body parts in relation to their physical size.