The palmaris longus is considered a phylogenetic degenerate metacarpophalangeal joint flexor muscle in humans, a small vestigial forearm muscle; it is the most variable muscle in humans, showing variation in position, duplication, slips and could be reverted. The palmaris longus (PL) is one of the most variable muscle reported up to 90% of humans. The characteristic of this muscle is shown by its short belly and long tendon. The belly soon gives way to a long slender tendon of variable length that inserts adherent across the front of the flexor retinaculum to the palmar aponeurosis Palmaris longus muscle is one of the superficial muscles of flexor compartment of forearm. Its main function is to anchor the skin and fascia of the hand. It is a weak flexor of the hand at wrist and tenses the palmar aponeurosis. It is one of the most variable muscles and is phylogenetically classified as a retrogressive muscle. The agenesis of Palmaris longus ranges from 0% to 63% with an overall 16% unilateral and 9% bilateral. It is very useful in orthopedics, cosmetic, plastic and reconstructive surgery