The leg is composed of five distinct sections: The hamstring muscles in the back of the thigh, the quadriceps muscles in the front, and the adductor muscles on . A number of issues can cause pain in the legs and ankles, which can leave you down and out for days. A strain is a torn or stretched muscle or tendon. Since the hamstring and quadriceps muscles cross at the hip and knee, they are at a high risk of being strained. Quadriceps Muscle Strain from aidmymuscle.com They allow you to move and provide support for your upper body. The hamstring muscles in the back of the thigh, the quadriceps muscles in the front, and the adductor muscles on . The hamstrings are three muscles at the back of the thigh that affect. Your upper leg muscle anatomy includes: A strain is a torn or stretched muscle or tendon. Ligaments connect bones to other bones.