Long Head (1a)
Origin: Superior part of the Ischial Tuberosity (4) 
Short Head (1b)
Origin: Lateral Lips of the Linea Aspera of the femur (5)
Insertion: Fibular Head and Lateral Tibial Condyle (6)
Actions: leg Flexion, hip Extension and leg Lateral Rotation with the knee slightly bent
Helping Synergist Muscles:
- together with Gluteus Maximus, Gluteus Medius, Semitendinosus (2), Semimembranosus (3), Adductor Magnus it acts to produce hip Extension
- Semitendinosus, Semimembranosus, Gastrocnemius, Gracilis and Popliteus when it acts to produce the leg Flexion
- together with Tensor Fasciae Latae it acts to produce the Lateral Rotation of the leg
Notes: it is the only one muscle which produce the Lateral Rotation of the knee. Both heads long and short provide rotary stability by preventing forward dislocation of the tibia on the femur during flexion