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Column of fornix

The column of fornix is a prominent white matter bundle within the limbic system of the brain. It represents the anterior descending part of the fornix, extending from the body of the fornix and coursing downward and forward toward the mammillary bodies. The columns of the fornix play a critical role in the circuit of Papez, acting as a major output tract for hippocampal efferents. They are important landmarks in neuroanatomy and radiology due to their involvement in memory circuits and proximity to other deep brain structures.

Anatomy & Description

  • The column of fornix (also known as crus or pillar) descends from the body of the fornix at the level of the interventricular foramen (of Monro).

  • Courses inferiorly, passing in front of the thalamus, to reach and terminate at the mammillary bodies.

  • Each fornix has two columns, one for each hemisphere, running parallel on either side of the midline.

Function

  • Major output tract of the hippocampus, carrying signals toward the mammillary bodies and hypothalamus.

  • Essential in the formation and consolidation of memory (limbic system).

  • Part of the Papez circuit, critical for emotional processing.

Arterial Supply

  • Supplied predominantly by small perforating branches from the anterior cerebral artery (ACA), especially the subcallosal and medial striate arteries.

  • Additional supply from branches of the anterior communicating artery and sometimes the posterior cerebral artery (PCA).

Venous Drainage

  • Drained primarily by small veins accompanying the fornix, emptying into the internal cerebral veins.

  • These in turn drain into the great cerebral vein (of Galen).

MRI Appearance:

T1-Weighted Images:

  • The column of fornix appears as a slightly hyperintense (bright) structure compared to surrounding gray matter.

  • Can be differentiated from the adjacent septal area and hypothalamus.

  • Well-defined and linear, following its anatomical course.

T2-Weighted Images:

  • Appears as a hypointense (dark) to isointense band compared to adjacent brain tissue.

  • Surrounded by the CSF of the lateral ventricles, which is bright on T2, providing good contrast.

  • Best seen on coronal and sagittal planes.

FLAIR Images:

  • The column of fornix is typically hypointense to isointense relative to gray matter.

  • Remains distinguishable from the hyperintense CSF, but contrast is reduced compared to T2.

  • Useful in detecting pathology such as demyelination or edema.

CT Appearance:

  • Appears as a subtle, thin, isodense band compared to surrounding brain parenchyma.

  • Difficult to delineate from adjacent white matter and gray matter on non-contrast CT.

  • Indirectly identified by its location relative to the lateral ventricles and thalamus.

MRI images

Column of fornix mri 3t sagittal image

MRI images

Column of fornix mri 3t coronal image