First sacral vertebra; fused component of sacrum
Expansion
Sacral vertebra 1
Purpose
Reference for lumbosacral spine anatomy; L5 to S1 most common disc herniation level
Clinical Context
Sacral vertebra 1 fused in sacrum (S1 to S5). L5 to S1 intervertebral disc most common herniation site. S1 radiculopathy causes sciatic pain, foot drop.
Related Terms
- L5
- Lumbosacral disc
Key Points
- L5 to S1 most common level for disc herniation; S1 nerve root compression causes sciatica, foot drop, loss of ankle reflex