Precentral gyrus

The precentral gyrus, also known as the primary motor cortex, is a very important structure involved in executing voluntary motor movements.  

Gross anatomy

The precentral gyrus is a vertically oriented cerebral convolution situated in the posterior portion of the frontal lobe. It is located immediately anterior to the central sulcus (fissure of Rolando), running parallel to it 1-2

In the precentral gyrus, large neurons known as Betz cells send efferent axons that terminate on the contralateral motor cranial and spinal nuclei. The functional organisation of the precentral gyrus is such that clusters of Betz cells are somatotopically represented by an inverted homunculus. Therefore, head and face regions are innervated by the inferior portion of the precentral gyrus. Conversely, the lower limbs are innervated by the superior portion 4.

Relations

Anterior to the precentral gyrus, separated by the precentral sulcus, lie a set of areas composing the lateral premotor cortex and the supplemental motor area. Posteriorly, separated by the central sulcus, lies the primary somatosensory cortex.

Medially and inferiorly, it is bound by the cingulate gyrus. Laterally and inferiorly, it is bound the Sylvian fissure 3

Neuroanatomy
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Article Information

rID: 45277
Section: Anatomy
Synonyms or Alternate Spellings:
  • Primary motor cortex
  • Motor strip
  • M1

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Cases and Figures

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    Figure 1: precentral gyrus
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    Figure 2: frontal lobe sulci
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