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Long gyri of insula

The long gyri of the insula are prominent ridges located in the posterior part of the insular cortex, deep within the lateral sulcus of the brain. They are separated from the short gyri of the insula by the central insular sulcus and play a significant role in various sensory and cognitive functions. Their unique location and connections make them crucial for integrating somatosensory, emotional, and autonomic information. Understanding their vascular supply and imaging appearance is essential for radiological and clinical assessment.

Synonyms

  • Long insular gyri

  • Posterior insular gyri

  • Gyri longi insulae (Latin)

  • Posterior gyri of the insula

Arterial Supply

  • Mainly supplied by branches of the middle cerebral artery (MCA), especially the insular branches of the MCA (M2 segment).

  • Additional minor contributions may come from small cortical branches of the anterior cerebral artery (ACA).

Venous Drainage

  • Drained predominantly by insular veins.

  • These veins drain into the deep middle cerebral vein and subsequently into the basal vein of Rosenthal and superior sagittal sinus.

Function

  • Integration of somatosensory information (pain, temperature, and touch perception).

  • Involved in visceral sensory processing (e.g., taste, visceral pain).

  • Plays a role in emotion, empathy, self-awareness, and some aspects of language.

  • Associated with autonomic control and homeostatic regulation.

MRI Appearance

  • T2-weighted MRI:

    • The long gyri of the insula appear as mildly hyperintense ridges relative to the surrounding white matter, with normal gray-white matter differentiation.

  • T1-weighted MRI:

    • Appear as hypointense (darker) compared to white matter, consistent with typical cortical gray matter appearance.

  • FLAIR MRI:

    • The long gyri maintain intermediate signal intensity (gray matter signal), without abnormal hyperintensity unless pathology (e.g., infarction, encephalitis) is present.

CT Appearance

  • On non-contrast CT, the long gyri of the insula are not distinctly visualized as individual gyri but appear as part of the insular cortex, which has the same density as other cortical gray matter.

  • Loss of insular ribbon (insular cortex blurring) is an early sign of MCA territory infarction on CT.

MRI images

Long gyri of insula mri 3t axial image

MRI images

Long gyri of insula mri 3t sagittal image

CT image

Long gyri of insula CT sag anatomy image -img-00001-00001