Hamstrings

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Other Names Thigh (Rear) Heads Biceps Femoris, Long Head Biceps Femoris, Short Head Semitendinosus Semimembranosus Movement Knee Flexion [1, 2, 3, 4 ] External Rotation [1, 2 ] Internal Rotation [3, 4 ] Hip Extension [1, 3, 4 ] Attachments Origin Ishium Ishial Tuberosity [1, 3, 4 ] Femur (posterior) [2 ] Linea Aspera Lateral Condyloid Ridge Insertion Tibia Lateral Condyle [1, 2 ]? Medial Condyle [3, 4 ] Fibula Head [1, 2 ] Related Muscles Gluteus Maximus Gastrocnemius Sartorius Gracilis Comments The biarticulate hamstring muscles [1, 3, 4 ] enter passive insufficiency through the completion of knee extension when the hips are more flexed or through the completion of hip flexion when the knees are more extended. The biarticulate hamstring muscles [1, 3, 4 ] enter active insufficiency through the completion of knee flexion when the hips are more extended (short head of biceps femoris [2 ] becomes more active) or through the completion of hip extension when the knees are more flexed (gluteus maximus becomes more active). Hamstring inflexibility is common in modern society. This may be explained by the principles of detraining (aka "use it or lose it"). Except in some cultures, we rarely keep the hamstring limber by sitting on the ground, bending over regularly, etc. as our ancestors had. It is only relatively recently, as far as evolutionary time is concerned, we stopped performing manual labor and began regularly sitting in chairs for prolonged periods of time. Also see hamstrings weakness.