sacrolumbar

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Of, relating to, or affecting the sacral and the lumbar region.

from The Century Dictionary.

• Pertaining to sacral and lumbar vertebræ; lumbosacral: as, the sacrolumbar muscle; sacrolumbar ligaments.
• Combining or representing the characters of sacral and lumbar parts: as, sacrolumbar vertebræ; sacrolumbar ribs.
• Also sacrilumbar.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective anatomy Of or pertaining to the sacrum and lumbar vertebrae; the loins.