The primary motor cortex (Brodmann area 4) is a brain region that in humans is located in the dorsal portion of the frontal lobe. It is the primary region of the motor system and works in association with other motor areas including premotor cortex, the supplementary motor area, posterior parietal cortex, and several subcortical brain regions, to plan and execute voluntary movements. 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 muscles.
At the primary motor cortex, motor representation is orderly arranged (in an inverted fashion) from the toe (at the top of the cerebral hemisphere) to mouth (at the bottom) along a fold in the cortex called the central sulcus. However, some body parts may be controlled by partially overlapping regions of cortex. Each cerebral hemisphere of the primary motor cortex only contains a motor representation of the opposite (contralateral) side of the body. The amount of primary motor cortex devoted to a body part is not proportional to the absolute size of the body surface, but, instead, to the relative density of cutaneous motor receptors on said body part.
The density of cutaneous motor receptors on the body part is generally indicative of the necessary degree of precision of movement required at that body part. For this reason, the human hands and face have a much larger representation than the legs.
For the discovery of the primary motor cortex and its relationship to other motor cortical areas, see the main article on the motor cortex.
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The primarymotorcortex (Brodmann area 4) is a brain region that in humans is located in the dorsal portion of the frontal lobe. It is the primary region...
immediately anterior to the central sulcus. The motorcortex can be divided into three areas: 1. The primarymotorcortex is the main contributor to generating...
The premotor cortex is an area of the motorcortex lying within the frontal lobe of the brain just anterior to the primarymotorcortex. It occupies part...
movement in the motorcortex, and sight in the visual cortex. The motorcortex is primarily located in the precentral gyrus, and the visual cortex is located...
covered by the frontal cortex. The frontal cortex includes the premotor cortex and the primarymotorcortex – parts of the motorcortex. The front part of...
midline surface of the hemisphere just in front of (anterior to) the primarymotorcortex leg representation. In monkeys the SMA contains a rough map of the...
The sensory cortex can refer informally to the primary somatosensory cortex, or it can be used as a term for the primary and secondary cortices of the...
areas 1, 2 and 3 are the primary somatosensory cortex; area 4 is the primarymotorcortex; area 17 is the primary visual cortex; and areas 41 and 42 correspond...
A motor neuron (or motoneuron or efferent neuron) is a neuron whose cell body is located in the motorcortex, brainstem or the spinal cord, and whose axon...
processing for different anatomical divisions of the body. The primary sensory cortex is located in the postcentral gyrus, and handles signals coming...
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...
primarymotorcortex, which is the last site in the cortex for processing motor commands. Though some areas of the human brain that receive primary sensory...
brain structures including the hippocampus, amygdala, primarymotorcortex, primary visual cortex and the fusiform gyrus. Tabi et al. (2022) used a variant...
supplemental motor area, and the premotor cortex. The primarymotorcortex is located in the precentral gyrus and is often visualized as the motor homunculus...
the parietal lobe from the frontal lobe and the primarymotorcortex from the primary somatosensory cortex. The evolution of the central sulcus is theorized...
of the posterior frontal lobe of the brain. It is the site of the primarymotorcortex that in humans is cytoarchitecturally defined as Brodmann area 4...
large part of the internal capsule, carrying motor information from the primarymotorcortex to the lower motor neurons in the spinal cord. Above the basal...
primarymotorcortex. These neurons are the largest in the central nervous system, sometimes reaching 100 μm in diameter. Betz cells are upper motor neurons...
paragraph in which primarymotorcortex in the intact hemisphere activates in concert with frontal premotor cortex and posterior parietal cortex presumably involved...
the motor areas, but also the primary somatosensory cortex and premotor areas. Most of the neurons originate in either the primarymotorcortex (precentral...
the parietal lobe from the frontal lobe and the primarymotorcortex from the primary somatosensory cortex. Macroscopically the hemispheres are roughly mirror...
nerves from the nonprimary motorcortex synapsing at the primarymotorcortex. Both divisions of the nonprimary motorcortex receive inputs from the thalamus...
discharge an action potential. If used in the primarymotorcortex, it produces muscle activity referred to as a motor evoked potential (MEP) which can be recorded...
actions. Upper motor neurons in the primarymotorcortex send their axons to the brainstem and spinal cord to synapse on the lower motor neurons, which...
aggregations of efferent nerve fibers from the upper motor neurons that travel from the cerebral cortex and terminate either in the brainstem (corticobulbar)...
Brodmann area 4 refers to the primarymotorcortex of the human brain. It is located in the posterior portion of the frontal lobe. Brodmann area 4 is part...
processes. An alpha-like variant called a mu wave can be found over the primarymotorcortex.[citation needed] Some researchers posit that there are at least...
sources of late BP were determined to be Area 4 (also known as the PrimaryMotorCortex) and Area 6. The current consensus is that the early BP starts first...
voluntary movement of skeletal muscle. From their origin in the primarymotorcortex, these nerves pass via the corona radiata to gather in the internal...