How to tell the difference between a pulled muscle and a torn muscle?

Graded 1 through 3..: Sprains & strains are graded based on the # of fibers w/in the structure that are stretched/ torn. This is by no means an exact # of fibers, but a grade 1 = fiber stretch, grade two = partial/ moderate disruption, & grade three = complete disruption. Symptoms of each are very similar but severity varies. Rice is the beginning treatment regardless of grade. Severe inj often need pt, sometime surger.