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Topic

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Isthmus of cingulate gyrus

The isthmus of the cingulate gyrus is a narrow cortical region forming part of the limbic system, situated at the posterior end of the cingulate gyrus. It acts as a bridge connecting the cingulate gyrus to the parahippocampal gyrus, and plays a role in integrating cognitive, emotional, and memory-related processes. The isthmus is a key anatomical landmark on neuroimaging and may be evaluated on MRI and CT for various neurological and neuropsychiatric conditions.

Synonyms

  • Cingulate isthmus

  • Isthmus gyri cinguli

  • Isthmus of cingulum

  • Isthmus of the limbic lobe

Function

  • Connects the posterior cingulate gyrus to the parahippocampal gyrus.

  • Involved in memory processing and emotional regulation via the limbic system.

  • Facilitates communication between cingulate and parahippocampal cortices.

  • May play a role in spatial navigation and contextual memory.

  • Associated with the default mode network in functional neuroimaging studies.

MRI Appearance

  • T1-weighted:

    • Appears as gray matter (intermediate to low signal) bordered by higher signal white matter.

    • Anatomical boundaries may be best appreciated on sagittal images.

  • T2-weighted:

    • Shows as hyperintense (higher signal) gray matter, distinguishing it from the hypointense (low signal) white matter.

    • The isthmus blends with adjacent limbic structures but retains cortical gray matter signal.

  • FLAIR:

    • Gray matter signal similar to other cortical areas.

    • FLAIR sequences are helpful for detecting subtle cortical lesions, demyelination, or infarction involving the isthmus.

CT Appearance

  • Not well distinguished from adjacent cortex due to limited soft tissue contrast.

  • Appears as part of the cortical ribbon, isodense with other gray matter.

MRI images

Isthmus of cingulate gyrus mri 3t axial image