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Central canal

The central canal is a slender, CSF-filled channel running longitudinally through the center of the spinal cord, extending from the caudal end of the fourth ventricle down to the conus medullaris. It is lined by ependymal cells and represents a remnant of the embryonic neural tube. Though its functional significance in adults is limited, the central canal plays a crucial role in the circulation of cerebrospinal fluid (CSF) during development and can be involved in various pathological conditions, such as syringomyelia.

Synonyms:

  • Ependymal canal

  • Spinal canal (central)

  • Central spinal canal

  • Canalis centralis (Latin)

Arterial Supply:

  • Primarily supplied by the anterior spinal artery

  • Supplemented by branches from the posterior spinal arteries

  • Segmental medullary arteries (from vertebral, intercostal, lumbar arteries) contribute along the length of the cord

Venous Drainage:

  • Drains via the anterior and posterior spinal veins

  • Venous blood is collected into the internal vertebral venous plexus

  • Ultimately drains into the systemic venous system via segmental veins

Function:

  • Acts as a conduit for cerebrospinal fluid (CSF) within the spinal cord

  • Plays a minor role in adult CSF circulation

  • Significant during embryonic development for neural tube patterning

  • In pathological conditions, can dilate and form cavities (syringomyelia)

MRI Appearance:

  • T2-weighted:

    • Central canal appears as a linear or dot-like hyperintense (bright) signal in the midline of the spinal cord, especially prominent if slightly dilated

    • Normally can be very thin and not always visible

  • T1-weighted:

    • The canal typically appears isointense to CSF (dark or low signal)

    • May not be well visualized unless abnormally dilated

  • FLAIR:

    • CSF within the central canal is suppressed, making the canal appear hypointense or not visible unless pathologically enlarged

    • May delineate abnormal cavities better than standard T1

CT Appearance:

  • The central canal is not routinely visible on CT due to its very small size and lack of contrast with surrounding cord tissue

  • May appear as a tiny hypodense line within the cord if significantly dilated

  • Pathological enlargement (e.g., syrinx) can sometimes be inferred if the cord is expanded with a central low-density area

MRI images

Central canal mri 3t axial image

MRI image

MRI Central canal coronal anatomy image