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Primary motor cortex is defined anatomically as the region of cortex that contains large neurons known as Betz cells, which, along with other cortical neurons, 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 ...
Depending on whether the damage is to the motor nerves, which regulate movement, or the sensory nerves, which affect the senses, the symptoms of a somatic nervous system problem can differ. [15] Damage to the motor nerves shows as: Loss of movement control; Spasms or cramps in muscles; Tremors or twitching; Wasting of muscles (muscle atrophy)
The corticospinal tract is a white matter motor pathway starting at the cerebral cortex that terminates on lower motor neurons and interneurons in the spinal cord, controlling movements of the limbs and trunk. [1] There are more than one million neurons in the corticospinal tract, and they become myelinated usually in the first two years of life.
Function corticospinal tract: from the motor cortex to lower motor neurons in the ventral horn of the spinal cord: The major function of this pathway is fine voluntary motor control of the limbs. The pathway also controls voluntary body posture adjustments. corticobulbar tract: from the motor cortex to several nuclei in the pons and medulla ...
The pyramidal tracts include both the corticobulbar tract and the corticospinal tract.These are aggregations of efferent nerve fibers from the upper motor neurons that travel from the cerebral cortex and terminate either in the brainstem (corticobulbar) or spinal cord (corticospinal) and are involved in the control of motor functions of the body.
The primary motor cortex receives terminating thalamocortical fibers from the VL nucleus of the thalamus. This is the primary pathway involved in the transference of cerebellar input to the primary motor cortex. The VA projects widely across the inferior parietal and premotor cortex.
The pyramidal tracts (corticospinal tract and corticobulbar tracts) may directly innervate motor neurons of the spinal cord or brainstem (anterior (ventral) horn cells or certain cranial nerve nuclei), whereas the extrapyramidal system centers on the modulation and regulation (indirect control) of anterior (ventral) horn cells.
There is a precise somatotopic representation of the different body parts in the primary motor cortex, with the leg area located medially (close to the midline), and the head and face area located laterally on the convex side of the cerebral hemisphere (cortical homunculus). The arm and hand motor area is the largest and occupies the part of ...