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Posterior long insular gyrus

The posterior long insular gyrus is a prominent structure within the insular cortex, located deep within the lateral sulcus of the brain. This gyrus forms the posterior segment of the long gyri of the insula and plays a key role in somatosensory and viscerosensory processing. Understanding its anatomy, vascular supply, function, and imaging characteristics is essential for clinicians and radiologists in the context of neuroimaging and neurological assessment.

Synonyms

  • Long posterior insular gyrus

  • Gyrus longus posterior insulae

  • Gyrus brevis insulae (less commonly, but sometimes confused in literature)

  • Posterior long gyrus of the insula

Arterial Supply

  • Primarily supplied by branches of the middle cerebral artery (MCA), specifically the insular branches of the MCA (M2 segment)

  • Additional minor supply from the anterior cerebral artery (ACA) through communicating insular branches

  • Some variability exists, but the MCA is consistently the main source

Venous Drainage

  • Venous blood from the posterior long insular gyrus drains into the deep middle cerebral vein (vena profunda media cerebri)

  • Connections with the superior sagittal sinus and basal vein of Rosenthal via insular veins

  • Drainage pattern may be variable but typically follows the deep venous system of the brain

Function

  • Involved in somatosensory integration, especially visceral sensory input (pain, temperature, and internal organ sensations)

  • Plays a role in autonomic control (such as heart rate, gastrointestinal sensations)

  • Participates in gustatory processing (taste perception)

  • Contributes to higher-level functions such as emotional processing and interoceptive awareness (perception of internal body states)

MRI Appearance

T1-weighted images:

  • Cortex appears as thin band of intermediate-to-low signal

  • Underlying white matter shows brighter signal

  • Gray-white differentiation preserved

T2-weighted images:

  • Cortex shows intermediate-to-high signal relative to white matter

  • White matter beneath gyrus is darker than cortex

  • Pathology (infarct, tumor, gliosis): appears bright

FLAIR (Fluid Attenuated Inversion Recovery):

  • Cortex: intermediate signal

  • White matter: dark relative to cortex

  • Pathology: infarct, demyelination, tumor → bright hyperintensity in cortex or subcortex

CT Appearance

Non-Contrast CT:

  • Cortex appears as thin gray density band with underlying hypodense white matter

  • Ischemia: loss of gray-white differentiation, hypodensity

  • Hemorrhage: hyperdensity within cortex or adjacent subcortex

Post-Contrast CT:

  • Normal cortex: no significant enhancement

  • Tumors: heterogeneous or ring-like enhancement

  • Infections/abscess: rim enhancement

  • Meningeal or cortical vessel involvement: enhancement along sulci

posterior long insular gyrus mri 3t axial image

posterior long insular gyrus mri 3t sagittal image

CT image

Posterior long insular gyrus CT axial anatomy image -img-00001-00001