Sprain
Sprain is an injury to a ligament or a joint capsule. There are some ligaments in the spine that can be injured, but these are rarely a significant cause of pain. The sacroiliac joint is full of ligaments and can be injured but this is also uncommon. Portions of the disc are made out of the same material as ligaments but a disc tear is very different than a sprain. You could use the “sprain” term loosely for a disc tear but it is poorly descriptive. A sprain is not a good term to use for the back.
