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Raphe of pons

The raphe of the pons is a slender, midline structure located within the ventral (basilar) portion of the pons in the brainstem. It consists of a longitudinal band of nerve fibers and nuclei, most notably the raphe nuclei, which play an essential role in modulating several neurological functions. The raphe of the pons serves as a key landmark in neuroanatomy and neuroimaging, forming part of the brainstem’s central axis and separating the two halves of the pons. Its anatomical and imaging features are important in differentiating pathological lesions from normal anatomical variations on MRI and CT.

Synonyms

  • Median raphe of pons

  • Pontine raphe

  • Midline raphe of pons

  • Pontine median line

Function

  • Contains several raphe nuclei (e.g., nucleus raphe magnus, nucleus raphe pontis)

  • Plays a role in the regulation of serotonergic neurotransmission

  • Modulates pain perception, mood, and arousal

  • Involved in sleep-wake regulation

  • Influences motor and autonomic functions via descending projections

Arterial Supply

  • Supplied primarily by small paramedian branches of the basilar artery

  • Additional supply from perforating arteries arising from:

    • Pontine arteries

    • Anterior inferior cerebellar artery (AICA)

Venous Drainage

  • Venous blood drains mainly into the median anterior pontomesencephalic vein

  • Also drains to the basal vein of Rosenthal and surrounding pontine veins

MRI Appearance

  • T1-weighted images:

    • Appears as a thin, midline hypointense (low signal) line separating the pontine tegmentum

    • Difficult to visualize unless there is pathology or midline shift

  • T2-weighted images:

    • Appears as a fine, linear hyperintense (high signal) line at the midline of the pons

    • May be seen more clearly in the absence of motion or artifact

  • FLAIR:

    • Similar to T2 appearance, but typically less conspicuous

    • Maintains linear midline hyperintensity if visualized

  • Post-contrast T1-weighted images:

    • Normally does not enhance

    • Enhancement may indicate pathology (e.g., infiltrative tumors, demyelination)

CT Appearance

  • Raphe of pons is generally not directly visible on CT due to limited resolution

MRI images

Raphe of pons mri 3t axial image