Hamstrings

The hamstrings are the tendons that attach the large muscles at the back of the thigh to bone. The hamstring muscles are the large muscles that pull on these tendons. It has become common in layman's terminology (and by some medical personnel) to refer to the long muscles at the back of the thigh as the "hamstrings" or "hamstring muscles." Academic anatomists refer to them as the posterior thigh muscles, and more specifically as the semimembranosis, the semitendinosis, and the biceps femoris muscles. These muscles span the thigh, crossing both the hip and the knee. They originate or begin at just below the buttocks, arising from the bone on which we sit (the ischium). They connect by means of their tendons onto the upper parts of the lower leg bones (the tibia and the fibula). - medicinenet. 

Sprains and strains are common injuries that share similar signs and symptoms, but involve different parts of your body.  A sprain is a stretching or tearing of ligaments — the tough bands of fibrous tissue that connect one bone to another in your joints. The most common location for a sprain is in your ankle. A strain is a stretching or tearing of muscle or tendon, 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. Initial treatment for both sprains and strains includes rest, ice, compression and elevation. Mild sprains and strains can be successfully treated at home. Severe sprains and strains sometimes require surgery to repair torn ligaments, muscles or tendons. - mayoclinic. 

A physical therapist or athletic trainer may oversee your rehabilitation program. For minor muscle pulls, you may need two to four weeks to safely get back to your activities. For more severe muscle tears, you may need rehabilitation for two to three months, with complete healing occurring by four to six months. At first, your therapist may use the RICE method. After three days, treatments may include contrast applications where heat and ice are alternated over 20 to 30 minutes. Ultrasound treatments may also be applied to improve blood flow and healing in the injured tissues. As your hamstrings begin to heal, it is critical that you follow an exercise program to regain your strength and mobility. Specially designed exercises encourage your body to rebuild muscle instead of scar tissue. The exercises also help prevent reinjury. Rehabilitation can be slow, so you will need to be patient and not push yourself too hard or too fast. - eorthopod.