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Topography of the primary motor cortex, showing which zone controls each body part Many of the brain areas defined by Brodmann have their own complex internal structures. In a number of cases, brain areas are organized into topographic maps , where adjoining bits of the cortex correspond to adjoining parts of the body, or of some more abstract ...
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 ...
The motor cortex is the region of the cerebral cortex involved in the planning, control, and execution of voluntary movements.The motor cortex is an area of the frontal lobe located in the posterior precentral gyrus immediately anterior to the central sulcus.
The primary motor cortex, which sends axons down to motor neurons in the brainstem and spinal cord, occupies the rear portion of the frontal lobe, directly in front of the somatosensory area. The primary sensory areas receive signals from the sensory nerves and tracts by way of relay nuclei in the thalamus .
A 2-D model of cortical sensory homunculus. A cortical homunculus (from Latin homunculus 'little man, miniature human' [1] [2]) is a distorted representation of the human body, based on a neurological "map" of the areas and portions of the human brain dedicated to processing motor functions, and/ or sensory functions, for different parts of the body.
Upper motor neurons (UMNs) is a term introduced by William Gowers in 1886. They are found in the cerebral cortex and brainstem and carry information down to activate interneurons and lower motor neurons, which in turn directly signal muscles to contract or relax. UMNs represent the major origin point for voluntary somatic movement.
Betz cells (also known as pyramidal cells of Betz) are giant pyramidal cells located within the fifth layer of the grey matter in the primary motor cortex. These neurons are the largest in the central nervous system, sometimes reaching 100 μm in diameter. [1] [2]
The corticospinal tract originates in several parts of the brain, including not just the motor areas, but also the primary somatosensory cortex and premotor areas. [1] Most of the neurons originate in either the primary motor cortex (precentral gyrus, Brodmann area 4) or the premotor frontal areas.