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Lunogracle fissure

The Lunogracile Fissure is a subtle longitudinal groove found on the posterior aspect of the spinal cord, particularly in the cervical and upper thoracic regions. It lies between the posterior median sulcus and the posterolateral sulcus, marking the division between the fasciculus gracilis (medially) and the fasciculus cuneatus (laterally). This fissure is more easily appreciated in the cervical spinal cord, where both fasciculi are present and well developed. The lunogracile fissure serves as an anatomical landmark for neuroanatomists and clinicians, aiding in the identification of sensory pathways within the dorsal columns.

Synonyms

  • Sulcus lunogracilis

  • Lunogracile sulcus

  • Intermediate dorsal sulcus

  • Posterior intermediate sulcus

Arterial Supply

  • Supplied primarily by the posterior spinal arteries (right and left), which run longitudinally along the dorsal aspect of the spinal cord.

  • Radicular branches from the segmental arteries (vertebral, intercostal, lumbar) may supplement the blood supply in specific spinal cord levels.

Venous Supply

  • Drained by the posterior spinal veins, which parallel the arterial supply.

  • These veins join the internal vertebral venous plexus, eventually draining into segmental veins.

Function

  • The fissure itself has no direct function but is an important anatomical landmark.

  • It demarcates the boundary between the fasciculus gracilis and fasciculus cuneatus within the dorsal columns, which are essential for transmitting fine touch, vibration, and proprioceptive sensations from the body to the brain.

  • Helps in neuroanatomical orientation during surgical procedures and imaging interpretation.

MRI Appearance

  • The fissure itself is not directly visualized due to its small size, but the posterior intermediate sulcus may appear as a faint linear hypointensity on T2-weighted axial images, especially in high-resolution sequences.

  • The fasciculus gracilis and cuneatus can be differentiated in the cervical region as paired columns separated by this sulcus.

  • Indirectly seen as the space between the two dorsal columns on axial images.

CT Appearance

  • The Lunogracile fissure is not typically visible on CT due to limited soft tissue contrast.

  • Occasionally, in high-resolution or post-mortem studies, the subtle groove between the dorsal columns may be appreciated.

  • CT myelography may outline the dorsal columns but does not delineate this fissure specifically.

MRI images

Lunogracle fissure MRI 3T coronal image

MRI images

Lunogracle fissure MRI 3T sagittal image

CT image

Lunogracle fissure CT sag anatomy image -img-00001-00001