Neural innervation patterns in the sacral vertebral body

Area of Science:

• Neuroanatomy
• Spinal Anatomy
• Histology

Background:

• The innervation pattern of the sacrum, particularly the S1 vertebral body, is not fully understood.
• Understanding nerve distribution is crucial for pain management and surgical approaches in the lumbosacral region.

Purpose of the Study:

• To map the nerve distribution within the S1 vertebral body.
• To specifically investigate nerve penetration and density at the superior endplate of S1, interfacing with the L5/S1 disc.

Main Methods:

• Dissection of sacral musculature and connective tissue.
• Histological analysis of S1 vertebral body coronal sections using a neural marker (PGP 9.5).
• 3D reconstruction of nerve distribution from high-resolution images.

Main Results:

• Nerves were predominantly found associated with blood vessels within the marrow space.
• Highest nerve density was observed at the S1 centrum, with secondary peaks at the lateral borders.
• Nerve fibers were seen penetrating the S1 lateral border, originating from anterior sacral nerves.

Conclusions:

• The S1 vertebral body and endplate exhibit dense innervation.
• Nerves penetrate the S1 vertebra laterally, unlike lumbar vertebrae which have posterior nutrient foramina.
• The identified nerves are likely a mix of nociceptive and autonomic fibers.