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Anterolateral medullary vein

The anterolateral medullary vein is a small but significant venous structure located on the lateral aspect of the medulla oblongata in the brainstem. It plays a key role in draining blood from the lateral medullary surface into larger collecting veins such as the lateral pontomesencephalic or anterior spinal veins. Recognition of this vein on imaging, especially advanced MRI and CT studies, aids in anatomical orientation and differentiation from pathologic vessels or lesions near the medulla.

Synonyms

  • Lateral medullary vein (less specific)

  • Anterolateral vein of medulla oblongata

  • Lateral medullary venous trunk

Function

  • Drains venous blood from the anterolateral surface of the medulla oblongata

  • Empties into the lateral pontomesencephalic vein or anterior spinal vein

  • Contributes to the superficial venous drainage of the brainstem

  • Plays a role in venous outflow from the inferior olivary nucleus and adjacent medullary structures

MRI Appearance

  • T2-Weighted Imaging

    • Appears as a linear or curvilinear low signal (flow void) along the lateral surface of the medulla

    • May be inconspicuous if the vessel is small or if flow is slow

    • Absence of abnormal surrounding signal helps differentiate from pathologic veins

  • T1-Weighted Imaging

    • Not typically well visualized due to small size and lack of contrast with surrounding tissue

    • Appears as a faint hypointense line paralleling the medullary surface

  • 3D Phase Contrast (PC 3D) MRI

    • Enhanced visualization of venous structures due to sensitivity to flow

    • Anterolateral medullary vein appears as a well-defined tubular structure on the lateral medulla

    • Useful for mapping venous anatomy and detecting venous variants

  • Post-Contrast T1-Weighted Imaging

    • Vein enhances after gadolinium administration, appearing as a thin, enhancing linear structure

    • Differentiated from arteries by location, course, and lack of arterial pulsation artifacts

    • Enhancing vein is usually best seen on high-resolution, thin-section images

CT Appearance

  • Non-Contrast CT

    • Typically not visualized due to small caliber and similar attenuation to adjacent parenchyma

  • CT Angiography (CTA) / CT Venography (CTV)

    • May be seen as a thin, enhancing linear structure along the anterolateral medullary surface

    • Visualization improves with high-resolution, multiplanar reconstructions

    • Most often appreciated in dedicated venous phase imaging

MRI images

Anterolateral medullary vein MRI 3T axial image