A long, thick thigh muscle, just medial to the iliacus. Its origins are on the transverse processes of the twelfth thoracic vertebra and lumbar vertebrae, and lumbar intervertebral discs. It shares a tendon of insertion with the iliacus with which it works in combination. Its primary action is flexion of the femur. It also flexes the spine and is an important postural muscle.
Subjects: Sports and Exercise Medicine.