Ion Channel Proteins
Primary Motor Cortex
The primary motor cortex (M1, or somatomotor area) occupies a large portion of the precentral gyrus (Brodmann area 4) and typically executes movements that are selected and planned by other areas of the brain.
- Each hemisphere has a primary motor cortex and both are organized by body region or somatotopically.
- The medial and superior portions control the actions of the feet, legs, trunk, and hands.
- The lateral portions control the actions of the head, mouth, and throat.
- The primary motor cortex on one side of the brain controls the muscles on the opposite side of the body.
- Nerve cell impulses (or action potentials) exit the motor cortex via upper level neurons, which cross over at the medulla pyramids.
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- The axons then enter the spinal cord as a part of the corticospinal tracts. Lower level neurons carry impulses from the ventral horns of the spinal cord to the skeletal muscles.