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Tenia of fornix

The taenia of fornix (also called the taenia fornicis) is a narrow white-matter band located along the medial margin of the fornix. It represents the line of attachment between the fornix and the choroid plexus of the lateral ventricle and is an important anatomical landmark in the ventricular system and limbic circuitry.

Although small, the taenia of fornix has significance in neuroanatomy, ventricular anatomy, and neurosurgical orientation, particularly in procedures involving the lateral ventricle and hippocampal region.

Synonyms

  • Taenia fornicis

  • Fornicial taenia

Location

  • Located along the medial border of the fornix

  • Runs longitudinally within the lateral ventricle

  • Forms the attachment line of the choroid plexus to the fornix

  • Situated between the body of the fornix and the thalamus

  • Extends from the region of the interventricular foramen (foramen of Monro) posteriorly toward the crus of the fornix

  • Forms part of the roof of the third ventricle via the fornix

Anatomical description

  • White-matter ridge:

    • Represents a thickened margin of the fornix

  • Ventricular landmark:

    • Marks the medial attachment of the choroid plexus

  • Developmental feature:

    • Corresponds to the junction between telencephalic and diencephalic structures

Relations

Medially:

  • Body of the fornix

Laterally:

  • Body of the lateral ventricle

Inferiorly:

  • Thalamus

Superiorly:

  • Septum pellucidum (anteriorly)

  • Corpus callosum (indirectly)

Associated structure:

  • Choroid plexus of the lateral ventricle (attached along the taenia)

Structures associated

  • Fornix: Major limbic white-matter tract

  • Choroid plexus: CSF-producing structure attached along the taenia

  • Lateral ventricle: Forms part of its medial boundary

Function

  • Structural attachment: Provides anchoring line for the choroid plexus

  • Anatomical demarcation: Separates ventricular roof structures from thalamic surface

  • Neurosurgical landmark: Aids orientation within the lateral ventricle

  • Limbic system association: Indirectly related to memory circuitry via the fornix

MRI appearance 

T1-weighted images:

  • Taenia of fornix: Intermediate signal intensity consistent with compact white matter

  • Best visualized: On high-resolution coronal and sagittal images

  • Appears as: A thin linear structure along the medial margin of the fornix

T2-weighted images:

  • Normal: Low-to-intermediate signal similar to adjacent white-matter tracts

  • Symmetry: Bilateral and symmetric appearance

FLAIR:

  • Normal: Typically inconspicuous

  • Identified by: Its anatomical position relative to fornix and ventricle

Diffusion-weighted imaging (DWI):

  • Normal: No diffusion restriction

Post-contrast T1-weighted images:

  • Normal: No enhancement

  • Choroid plexus: Enhances normally adjacent to the taenia, helping delineation

CT appearance 

Non-contrast CT:

  • Taenia of fornix: Not individually visualized

Post-contrast CT:

  • Normal: No enhancement of the taenia itself

MRI image

MRI Tenia of fornix anatomy image -img-00000-00000

MRI image

MRI Tenia of fornix anatomy image -img-00000-00000_00001