Strained Biceps Femoris Muscle Anatomy
To better understand a hamstring strain, it helps to understand the anatomy of the thigh.
The entire leg contains four bones:
The hamstring muscles are a group of three muscles in the back of the thigh:
- Biceps femoris
One end of each muscle attaches to the bottom of the pelvis, and the other end attaches to the end of the femur, at the knee. The hamstring muscles extend the hip (move the hip to the rear) and flex the knee.
The hamstrings are the powerful flexors of the knee joint. They are essential to stabilizing the knee and performing activities such as running.
- Brockett CL, Morgan DL, Proske U. Predicting hamstring strain injury in elite athletes. Med Sci Sports Exerc. 2004 Mar;36(3):379-87. 
- Koulouris G, Connell D. Evaluation of the hamstring muscle complex following acute injury. Skeletal Radiol. 2003 Oct;32(10):582-9. 
- Verrall GM, Slavotinek JP, Barnes PG, Fon GT. Diagnostic and prognostic value of clinical findings in 83 athletes with posterior thigh injury: comparison of clinical findings with magnetic resonance imaging documentation of hamstring muscle strain. Am J Sports Med. 2003 Nov-Dec;31(6):969-73.