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Insular cortex

The insular cortex, also known as the insula or island of Reil, is a deep-seated region of the cerebral cortex located within the lateral sulcus, hidden beneath the frontal, temporal, and parietal opercula. The insula plays a critical role in diverse functions including perception, emotion, autonomic control, and homeostasis. Its unique anatomical position and involvement in multiple brain networks make it essential in both clinical and research neuroanatomy.

Synonyms:

  • Insula

  • Island of Reil

  • Insular lobe

Arterial Supply:

  • Middle Cerebral Artery (MCA): Primary supply via insular branches (especially M2 segment).

  • Lateral lenticulostriate arteries: May contribute to deep insular areas.

  • Anterior cerebral artery (rare): Minimal supply in some variants.

Venous Drainage:

  • Superficial middle cerebral vein: Drains lateral and superior surfaces.

  • Deep middle cerebral vein: May drain deeper portions.

  • Basal vein of Rosenthal: Receives deep venous return in some cases.

Functions:

  • Sensory processing: Integrates somatosensory, visceral, and pain stimuli.

  • Autonomic regulation: Controls cardiovascular, respiratory, and gastrointestinal responses.

  • Emotional experience: Involved in empathy, disgust, and risk prediction.

  • Homeostatic integration: Coordinates body awareness and interoception.

  • Taste perception: Gustatory cortex located in the anterior insula.

MRI Appearance:

  • T1-weighted images: Insular cortex is isointense to other cortical white matter; sulci may appear as low-signal spaces.

  • T2-weighted images: Cortex appears hyperintense relative to white matter; well-defined gray-white differentiation.

  • FLAIR: Similar to T2, but with suppressed CSF signal; insular cortex highlights well against adjacent opercula and white matter.

CT Appearance:

  • The insular cortex appears as a thin rim of gray matter deep within the Sylvian fissure.

  • Early ischemic change: Loss of gray-white differentiation in the insular ribbon ("insular ribbon sign") is a key early finding in MCA territory infarct.

  • Normal: Insular cortex is otherwise indistinct from surrounding cortex on non-contrast CT.

MRI images

insular cortex mri 3t sagital image

CT image

Insular cortex CT sagittal anatomy image -img-00001-00001