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Paracentral gyrus

The paracentral gyrus is a cortical region located on the medial surface of the cerebral hemisphere, forming the medial continuation of the precentral and postcentral gyri. It contains critical motor and sensory representations of the contralateral lower limb and plays an essential role in voluntary movement, somatosensory perception, and sphincter control.

Because of its functional importance, the paracentral gyrus is frequently evaluated in stroke, tumors, epilepsy, demyelinating disease, and functional neuroimaging.

Synonyms

  • Paracentral lobule (functional term)

Location

  • Situated on the medial surface of the cerebral hemisphere

  • Surrounds the medial end of the central sulcus

  • Bounded anteriorly by the paracentral sulcus

  • Bounded posteriorly by the marginal branch of the cingulate sulcus

  • Superior continuation of the precentral and postcentral gyri

  • Forms part of the medial frontal and parietal lobes

  • Adjacent inferiorly to the cingulate gyrus

Anatomical components

  • Anterior portion:

    • Medial continuation of the precentral gyrus

    • Corresponds to the primary motor cortex (Brodmann area 4)

  • Posterior portion:

    • Medial continuation of the postcentral gyrus

    • Corresponds to the primary somatosensory cortex (Brodmann areas 3, 1, 2)

Relations

Anteriorly:

  • Medial frontal gyrus

  • Supplementary motor area (SMA)

Posteriorly:

  • Precuneus

Inferiorly:

  • Cingulate sulcus

  • Cingulate gyrus

Superiorly:

  • Superomedial margin of the cerebral hemisphere

Laterally:

  • Continuous with lateral precentral and postcentral gyri

Vascular supply

  • Anterior cerebral artery (ACA)

  • Primarily supplied by the pericallosal and callosomarginal branches

Function

  • Motor control: Voluntary movement of the contralateral lower limb

  • Somatosensory perception: Sensation from the contralateral lower limb

  • Autonomic and sphincter control: Involved in voluntary bladder and bowel function

  • Motor planning integration: Functional interaction with supplementary motor area

MRI appearance

T1-weighted images:

  • Normal cortex: Intermediate gray-matter signal with clear gray–white differentiation

T2-weighted images:

  • Normal cortex: Intermediate-to-slightly hyperintense signal relative to white matter

FLAIR:

  • Normal: Uniform cortical signal with suppressed CSF in adjacent sulci

  • Pathology: Hyperintense cortical or juxtacortical lesions in infarction, MS, or tumor

Diffusion-weighted imaging (DWI):

  • Normal: No diffusion restriction

  • Acute infarction: Bright restricted diffusion with low ADC values in ACA territory

Post-contrast T1-weighted images:

  • Normal: No enhancement

CT appearance

Non-contrast CT:

  • Normal: Cortical anatomy often subtle on medial surface

Post-contrast CT:

  • Normal: Minimal cortical enhancement

MRI images

MRI Paracentral gyrus axial anatomy image -img-00000-00000

MRI images

MRI Paracentral gyrus sagittal anatomy image -img-00000-00000_00001