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Topic

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Posterior orbital gyrus

The posterior orbital gyrus is one of the orbital gyri located on the inferior (orbital) surface of the frontal lobe, forming part of the prefrontal cortex. It is positioned posteriorly among the orbital gyri, separated from the anterior and lateral orbital gyri by shallow sulci. The posterior orbital gyrus plays a role in higher cognitive and emotional processing, being adjacent to important limbic and prefrontal structures. This gyrus is most easily appreciated on axial and coronal brain images, where its distinctive location along the orbital surface aids in identification.

Synonyms

  • Posterior orbital convolution

  • Gyrus orbitalis posterior

  • Caudal orbital gyrus

Arterial Supply

  • Primarily supplied by branches of the anterior cerebral artery (ACA), specifically the orbitofrontal artery (a branch of the ACA).

  • Contributions may also arise from small branches of the middle cerebral artery (MCA).

Venous Drainage

  • Drains mainly into the superior sagittal sinus via the superior cerebral veins.

  • Additional drainage may occur through the inferior cerebral veins to the cavernous sinus.

Function

  • Involved in executive functions, such as decision-making and behavioral regulation.

  • Participates in emotional and social cognition due to connections with limbic and prefrontal areas.

  • May contribute to olfactory processing due to its location near the olfactory tract and bulb.

MRI Appearance

T1-weighted images:

  • Cortex: intermediate signal intensity

  • White matter beneath gyrus: slightly brighter signal

  • CSF in sulci: dark

T2-weighted images:

  • Cortex: intermediate to slightly brighter signal

  • White matter: relatively darker than cortex

  • CSF in sulci: bright

FLAIR (Fluid Attenuated Inversion Recovery):

  • Cortex: intermediate gray signal

  • White matter: darker signal

  • CSF: dark (suppressed)

  • Pathology (edema, gliosis, tumor): bright hyperintensity

CT Appearance

Non-Contrast CT:

  • Cortex: gray matter density slightly higher than white matter

  • White matter: lower attenuation than cortex

  • CSF: very low attenuation (dark)

  • Pathology: hemorrhage appears hyperdense, infarct hypodense

Post-Contrast CT:

  • Normal cortex: minimal enhancement

  • Pathology:

    • Tumors (glioma, metastasis, meningioma): heterogeneous or focal enhancement

    • Infection: meningeal or cortical enhancement along sulci

    • Vascular lesions: strong contrast enhancement

MRI images

posterior orbital gyrus MRI 3T axial image

MRI images

posterior orbital gyrus MRI 3T sagittal image

CT image

Posterior orbital gyrus CT axial anatomy image -img-00001-00001_00001