The palmaris longus (or palmaris longus muscle, latin: musculus palmaris longus) is a long, flat, superficial muscle of the forearm that belongs to the anterior muscle group and lies in the first layer.
The palmaris longus originates from the medial epicondyle of the humerus.
The palmaris longus descends obliquely and ends in a flattened tendon that passes over the flexor retinaculum and inserts into the palmar aponeurosis.
The main function of the palmaris longus is flexion of the hand.
The palmaris longus is innervated by the median nerve.