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Topic

design image
Septum pellucidum

The septum pellucidum is a thin, vertically oriented, double-layered membrane located in the midline of the brain. It separates the anterior horns of the left and right lateral ventricles and extends from the corpus callosum above to the fornix below. Although it does not contain neural tissue, the septum pellucidum serves as an important anatomic landmark within the ventricular system and plays a minor role in separating the lateral ventricles.

Synonyms

  • Septum lucidum

  • Transparent septum

Function

  • Primarily a thin membrane dividing the anterior horns of the lateral ventricles

  • Lacks significant functional neural tissue

  • Acts as a landmark in neuroimaging and neurosurgery

  • Sometimes associated with neurodevelopmental disorders when absent or malformed

Arterial Supply

  • Anterior cerebral artery (ACA), via its medial striate branches

  • Anterior communicating artery, through small perforating branches

  • Occasionally small branches from the pericallosal artery

Venous Drainage

  • Small veins of the septum pellucidum drain primarily into the internal cerebral veins

  • Some minor drainage into the anterior septal veins

MRI Appearance

T2-weighted Imaging

  • Thin hypointense (dark) linear structure between the lateral ventricles

  • The space of the septum pellucidum may be seen as a thin, CSF-like, hyperintense line if present

T1-weighted Imaging

  • Appears as a thin, isointense line

  • The cavum septum pellucidum (if present) will appear hypointense (dark), similar to CSF

FLAIR Imaging

  • The septum itself is typically not well-visualized due to its thinness

  • Cavum (if present) will be suppressed, appearing dark like CSF

Post-Contrast T1-weighted Imaging

  • No significant enhancement under normal conditions

  • Pathologic processes involving adjacent structures may result in enhancement nearby, but the septum pellucidum itself does not enhance

CT Appearance

  • Not directly visualized due to its thin and membranous nature

  • Appears as a linear low-density structure separating the frontal horns of the lateral ventricles

  • Cavum septum pellucidum may be seen as a CSF density space if prominent

MRI images

Septum pellucidum mri 3t coronal image