Nonprimary motor cortex

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. Both divisions of the nonprimary motor cortex receive inputs from the thalamus and are responsible for sensory guidance and motor preparation.

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

References

1. (1985). "The primate premotor cortex: past, present, and preparatory". Annu Rev Neurosci.
2. (2004). "The Human Nervous System". Elsevier.
3. Fink, Gereon R.. (April 1997). "Multiple Nonprimary Motor Areas in the Human Cortex". J. Neurophysiol..
4. Tanji, Jun. (June 1987). "Relation of neurons in the nonprimary motor cortex to bilateral hand movement". Nature.
5. (2000). "Organization of Nonprimary Motor Cortical Inputs on Pyramidal and Nonpyramidal Tract Neurons of Primary Motor Cortex: An Electrophysiological Study in the Macaque Monkey". Cereb. Cortex.
6. (November 1984). "Anatomical and physiological organization of the non-primary motor cortex". Trends in Neurosciences.