GROSS ANATOMY

Detailed explanation-1: -The iliopsoas muscle is the strongest hip flexor and assists in external rotation of the femur, playing an important role in maintaining the strength and integrity of the hip joint. It is essential for correct standing or sitting lumbar posture, and during walking and running.

Detailed explanation-2: -The iliopsoas muscle is the strongest flexor of the hip joint. Simultaneous contraction of the psoas major and iliacus muscles produces a powerful flexion of the thigh at the hip joint. However, psoas major can independently act on its attachment on the lumbar spine when its distal end is fixed.

Detailed explanation-3: -Thus, the rectus femoris is used more during 0°–45° hip flexion, to induce anterior tilting and hip flexion of the pelvis, whereas rectus abdominis activation is used for hip flexion at 45° and greater, to induce hip flexion accompanied by posterior tilting of the pelvis.

Detailed explanation-4: -Its functions are to flex the thigh at the hip joint and to extend the leg at the knee joint.