The palmaris longus muscle is one of the most variable muscles in the body and is sometimes (10% of the time) absent. It may be mostly tendon near the point of attachment and muscular at the far end, or it may be muscular in the center with tendons above and below. It may have two bundles of muscle with a central tendon, or it may be made up of a tendinous band, or the muscle make-up may be doubled.mycontentbreak Its function is to flex the hand at the wrist.