A sprain is a stretching or tearing of ligaments – the tough bands of fibrous tissue that connects two bones together in your joints. The most common location for a sprain is in your ankle. It can be caused by overextending or tearing a ligament while severely stressing a joint.
A strain is a stretching or tearing of muscle or tendon. A tendon is a fibrous cord of tissue that connects muscles to bones. Strains often occur in the lower back and in the hamstring muscle in the back of your thigh. There are two types of strains – acute and chronic. An acute strain is caused when a muscle stretches unusually far or abruptly. A chronic strain is caused by prolonged, repetitive movement of a muscle.