Mootorikorpuses

Mootorikorpuses, or the motor cortex, is a region of the cerebral cortex involved in planning, control, and execution of voluntary movements. In humans it lies in the frontal lobe along the precentral gyrus and includes the primary motor cortex as well as premotor and supplementary motor areas.

Anatomy and organization: The primary motor cortex, Brodmann area 4, occupies the precentral gyrus. Adjacent premotor cortex (area 6) and the supplementary motor area contribute to planning and sequencing of movements. The motor cortex contains a somatotopic map, often described as the motor homunculus, with representations for different body parts arranged along the gyrus. Lateral portions primarily govern the face and hands, while medial portions relate to the trunk and legs.

Connections and pathways: The motor cortex integrates input from the somatosensory cortex, thalamus, cerebellum, and basal ganglia via cortico-thalamic and cortico-basal circuits. Output is primarily through the corticospinal tract to spinal motor neurons and the corticobulbar tract to brainstem nuclei, coordinating voluntary movement. The organization shows contralateral control: activity in one hemisphere largely influences the opposite side of the body.

Functions and plasticity: It is involved in the execution of movement, precision of timing and force, and motor learning and adaptation. The motor cortex exhibits plasticity, with maps shifting in response to training, injury, or rehabilitation efforts.

Clinical relevance and research: Lesions in the motor cortex can cause contralateral weakness or paralysis, while seizures may originate there. Modern imaging and stimulation techniques, such as functional MRI and transcranial magnetic stimulation, are used to map its function and guide rehabilitation.