The piriformis rotates the thigh laterally. When the hip is flexed greater than 90 degrees it then it rotates the thigh medially.
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One effective joint action for the piriformis muscle is external rotation of the hip joint. This means that when the piriformis contracts, it helps in rotating the thigh bone outward at the hip joint.
Piriformis syndrome is caused by the piriformis muscle compressing the sciatic nerve, leading to pain and discomfort in the buttocks and down one leg. This compression can be a result of muscle tightness, injury, overuse, or anatomical variations in the piriformis muscle. Physical activities that involve repetitive movements or sitting for prolonged periods can also contribute to the development of piriformis syndrome.
The antagonist to the psoas muscle is the gluteus maximus, which performs the opposite action to the psoas by extending the hip joint. This means that when the psoas contracts to flex the hip joint, the gluteus maximus relaxes or lengthens to allow for this movement.
The joint action in leg extensions is knee extension, where the angle between the thigh and lower leg decreases. The main muscles involved in this action are the quadriceps, specifically the vastus medialis, vastus lateralis, vastus intermedius, and rectus femoris. The movement primarily occurs at the knee joint.
No, the rotator cuff is a group of muscles and tendons that support and stabilize the shoulder joint, not the elbow joint. The flexibility at the elbow joint is mainly due to the action of different muscles like the biceps and triceps.
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