The prevalence and morphology of the palmaris longus muscle employed as flaps in reconstructive surgery

Abstract

The desire to replace missing tissue in the human body has existed since the beginning of medicine. A donor flap is usually selected for transfer because it is thought to be nonessential in its original location, meaning that the donor site can survive without the presence of this tendon and the functionality is not compromised. This is the case with the palmaris longus (PL) muscle which is found to be frequently missing without any adverse effects and it has also been described as a phylogenetically degenerative structure. The PL muscle remains a key choice for tendon harvest. The literature describes it as a vestigial muscle, characterized by a short belly and long tendon. The muscle is absent in 4-30% of the population and it has been suggested that if the muscle is absent on one side, that there is a 30% chance that it will be present on the contra-lateral side of the body. The prevalence of this muscle has never been determined in a South African population. To test for the presence of the PL muscle, the wrist should be flexed against resistance and the thumb and little finger should be opposed, which in turn will tense the muscle and, if present, will be visible on the forearm. The aims of this study were to determine the prevalence of the PL muscle in South African population and to describe the macroscopic structure of this muscle. The presence or absence of the PL muscle was determined in a sample of 300 individuals. The macroscopic structure of the PL muscle, if present, was determined by carefully exposing the muscle in a sample of 50 adult cadavers. The mean length and breadth of the muscle belly and tendon was measured and all results were analysed and discussed.