Action
The piriformis muscle is part of the lateral rotators of the hip, along with the quadratus femoris, gemellus inferior, gemellus superior, obturator externus, and obturator internus. The piriformis laterally rotates femur with hip extension and abducts femur with hip flexion. Abduction of the flexed thigh is important in the action of walking because it shifts the body weight to the opposite side of the foot being lifted, which keeps us from falling. The action of the lateral rotators can be understood by crossing your legs to rest an ankle on the knee of the other leg. This causes the femur to rotate and point the knee laterally. The lateral rotators also oppose medial rotation by the gluteus medius and gluteus minimus. At a range of more than 90 degrees the actions of the piriformis are reversed to adduct and internally rotate (medial).
Read more about this topic: Piriformis Muscle
Famous quotes containing the word action:
“Let no one say that taking action is hard. Action is aided by courage, by the moment, by impulse, and the hardest thing in the world is making a decision.”
—Franz Grillparzer (1791–1872)
“The bugle-call to arms again sounded in my war-trained ear, the bayonets gleamed, the sabres clashed, and the Prussian helmets and the eagles of France stood face to face on the borders of the Rhine.... I remembered our own armies, my own war-stricken country and its dead, its widows and orphans, and it nerved me to action for which the physical strength had long ceased to exist, and on the borrowed force of love and memory, I strove with might and main.”
—Clara Barton (1821–1912)
“The moment we choose to love we begin to move against domination, against oppression. The moment we choose to love we begin to move towards freedom, to act in ways that liberate ourselves and others. That action is the testimony of love as the practice of freedom.”
—bell hooks (b. c. 1955)