nonprimary motor cortex
{{Short description|Region in the human brain}}
Nonprimary motor cortex is a functionally defined portion of the frontal lobe. It includes two subdivisions, the premotor cortex and the supplementary motor cortex. Largely coincident with the cytoarchitecturally defined area 6 of Brodmann (human), it is located primarily in the rostral portion of the precentral gyrus and caudal portions of the superior frontal gyrus and the middle frontal gyrus,{{cite journal|vauthors=Wise SP|year=1985|title=The primate premotor cortex: past, present, and preparatory|journal=Annu Rev Neurosci|volume=8|pages=1–19|pmid=3920943|doi=10.1146/annurev.ne.08.030185.000245|s2cid=11359075 }}{{cite book |vauthors=Zilles K |year=2004 |chapter=27: Architecture of the human cerebral cortex |title=The Human Nervous System |edition=2nd |veditors=Paxinos G, Mai JK |publisher=Elsevier |location=Amsterdam |oclc=54767534}} It aids in cerebral control of movement. Anatomically speaking, several nonprimary areas exist, and make direct connections with the spinal cord.{{cite journal | title=Multiple Nonprimary Motor Areas in the Human Cortex | author=Fink, Gereon R.| journal=J. Neurophysiol. |date=April 1997 | volume=77 | issue=4 | pages=2164–2174 | pmid=9114263|display-authors=etal| doi=10.1152/jn.1997.77.4.2164 }}
Function
The nonprimary motor cortex exerts its motor control at a higher neural level than the primary motor cortex by commanding the laterality of muscular motor response to the brain. This is carried out by afferent nerves from the nonprimary motor cortex synapsing at the primary motor cortex.{{cite journal | title=Relation of neurons in the nonprimary motor cortex to bilateral hand movement | author=Tanji, Jun | journal=Nature |date=June 1987 | volume=327 | pages=618–620 | doi=10.1038/327618a0 | issue=6123 | pmid=3600757| bibcode=1987Natur.327..618T | s2cid=31274821 }}{{cite journal | title=Organization of Nonprimary Motor Cortical Inputs on Pyramidal and Nonpyramidal Tract Neurons of Primary Motor Cortex: An Electrophysiological Study in the Macaque Monkey |author1=Tokuno, Hironobu |author2=Nambu, Atsushi |name-list-style=amp | journal=Cereb. Cortex | year=2000 | volume=10 | issue=1 | pages=58–68 | doi=10.1093/cercor/10.1.58| pmid=10639396 | doi-access=free }} Both divisions of the nonprimary motor cortex receive inputs from the thalamus and are responsible for sensory guidance and motor preparation.{{cite journal | url=http://www.cell.com/trends/neurosciences/abstract/S0166-2236(84)80150-2 | title=Anatomical and physiological organization of the non-primary motor cortex |author1=Wisea, Steven P. |author2=Strick, Peter L. |name-list-style=amp | journal=Trends in Neurosciences |date=November 1984 | volume=7 | issue=11 | pages=442–446 | doi=10.1016/S0166-2236(84)80150-2| s2cid=53173366 | url-access=subscription }}
Supplementary Motor Cortex
The supplementary portion receives inputs from the thalamus. The thalamic nuclei supplying the supplementary motor cortex are distinct from those enervating the primary motor cortex. (Trends in Neurosciences) It is located above the cingulate sulcus inside the anterior paracentral lobule.
Premotor Cortex
Neural information to the premotor cortex is supplied by the cerebellum. It is located dorsally in and around the precentral sulcus. Laterally, this exists at the dorso-ventral level of the hand in the motor cortex. A ventral region may also exist, but its exact anatomical location is disputed. Like the primary motor cortex, corticospinal tracts begin in the premotor area.
References
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External links
- More information at [http://braininfo.rprc.washington.edu/centraldirectory.aspx?ID=2397 BrainInfo]