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Piriformis Muscle
The piriformis muscle () is a flat, pyramidally-shaped muscle in the gluteal region of the lower limbs. It is one of the six muscles in the lateral rotator group. The piriformis muscle has its origin upon the front surface of the sacrum, and inserts onto the greater trochanter of the femur. Depending upon the given position of the leg, it acts either as external (lateral) rotator of the thigh or as abductor of the thigh. It is innervated by the piriformis nerve. Structure The piriformis is a flat muscle, and is pyramidal in shape. Origin The piriformis muscle originates from the anterior (front) surface of the sacrum by three fleshy digitations attached to the second, third, and fourth sacral vertebra. It also arises from the superior margin of the greater sciatic notch, the gluteal surface of the ilium (near the posterior inferior iliac spine), the sacroiliac joint capsule, and (sometimes) the sacrotuberous ligament (more specifically, the superior part of the pelvic sur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lateral Rotator Group
The lateral rotator group is a group of six small muscles of the hip which all externally (laterally) rotate the femur in the hip joint. It consists of the following muscles: piriformis, gemellus superior, obturator internus, gemellus inferior, quadratus femoris and the obturator externus. All muscles in the lateral rotator group originate from the hip bone and insert on to the upper extremity of the femur. The muscles are innervated by the sacral plexus ( L4- S2), except the obturator externus muscle, which is innervated by the lumbar plexus. Individual muscles Other lateral rotators This group does not include all muscles which aid in lateral rotation of the hip joint: rather it is a collection of ones which are known for primarily performing this action. Other muscles that contribute to lateral rotation of the hip include: *Gluteus maximus muscle (lower fibres) *Gluteus medius muscle and gluteus minimus muscle when the hip is flexed (become medial rotators when hip is exte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
