Muscle tissue is elastic and can absorb a tremendous amount of shock. A strain is a stretching and tearing of muscle tissue. The more severe strain may be called a rupture or complete tear. Strains are often caused by lifting something heavy, overuse or overtraining. Strains usually involve the muscles in the neck, back, thigh, or the back of the lower leg.
Some strains can reoccur, especially in the neck or back.
A sprain is an injury to a ligament. Ligament tissue connects bone to bone. Ligaments are found around joints and are nonelastic. Unlike muscle tissue, ligament tissue does not contract when stretched. When this occurs, ligaments allow for greater joint motion.