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Cauda equina anatomy. I: Intrathecal nerve root organization.
E J Wall1, M S Cohen, J B Massie
1Division of Orthopaedics and Rehabilitation, University of California, San Diego.
Spine
|December 1, 1990
Summary
This study reveals the previously undescribed 3D anatomy of the human cauda equina. New fixation techniques clarified the consistent arrangement of nerve roots within the thecal sac.
Area of Science:
- Anatomy
- Neuroscience
- Medical Imaging
Background:
- The detailed 3D organization of the human cauda equina remains largely undescribed.
- Dissecting individual, unfixed nerve roots presents significant anatomical challenges.
Purpose of the Study:
- To define the cross-sectional anatomy of the human cauda equina.
- To elucidate the three-dimensional arrangement of nerve roots within the thecal sac.
Main Methods:
- A novel in situ fixation and embedding technique was developed and applied.
- 15 fresh human cadavers were utilized for anatomical definition.
- Cross-sectional anatomy was analyzed from the L2-L3 to L5-S1 levels.
Main Results:
- A highly consistent cross-sectional pattern of the cauda equina was observed across all specimens.
- Lower sacral (S2-S5) and coccygeal roots were located dorsally within the thecal sac.
- Lumbar and first sacral roots showed an ascending oblique, layered pattern with motor bundles anteromedial to sensory bundles.
Conclusions:
- The study describes a previously unknown 3D anatomy of the cauda equina.
- This detailed anatomical understanding may improve diagnosis and treatment of cauda equina pathologies.
- Arachnoid invaginations play a role in fixing nerve root relationships within the thecal sac.