The sacral promontory has which joint attached to it?

The sacral promontory has which joint attached to it?

• A. L5-S1 disc
• B. L4-L5 disc
• C. L3-L4 disc
• D. L2-L3 disc

Answer: (A)

The sacral promontory is the anterior edge of the first sacral vertebra, marking the lumbosacral boundary. The joint that attaches there is the intervertebral disc between the last lumbar vertebra and the first sacral vertebra—between L5 and S1. This L5–S1 disc sits against the sacrum, with its superior endplate contacting L5 and its inferior endplate contacting S1, effectively anchoring to the promontory. Discs higher up (between L4–L5, L3–L4, or L2–L3) lie above the promontory and do not attach to it.

The sacral promontory is the anterior edge of the first sacral vertebra, marking the lumbosacral boundary. The joint that attaches there is the intervertebral disc between the last lumbar vertebra and the first sacral vertebra—between L5 and S1. This L5–S1 disc sits against the sacrum, with its superior endplate contacting L5 and its inferior endplate contacting S1, effectively anchoring to the promontory. Discs higher up (between L4–L5, L3–L4, or L2–L3) lie above the promontory and do not attach to it.