A possible phylogenetic degeneration of the palmaris longus muscle

Abstract

Variations in the human muscular system are common and may vary with the side of the body or sex of the subject. The palmaris longus muscle (PL) is subject to variability. PL is frequently found to be missing without any adverse effects. This makes the PL appear to be vestigial and has also been described to be phylogenetically degenerative. The PL is occasionally absent in vertebrates who do not use their forelimbs in ambulation. It is suggested that the function of this muscle have been taken over by the other flexors in the limbs. This has yet to be determined in a South African population The aims of this study are therefore to firstly determine the prevalence of PL in a South African population and, secondly, to determine whether there exists a phylogenetic degenerative trend for the PL. A sample of 600 participants was randomly selected from various age groups. The prevalence of the PL muscle was determined with a 95% confidence interval. Further statistical analysis included comparisons of the prevalence of the muscle between males and females and left and right sides using a student t-test. A Chi-squared test was used to determine a possible trend in phylogenetic degeneration of the PL muscle within the six groups. The ages of the participants ranged from 5 to 99 years. Preliminary results have shown that the PL muscles is unilaterally absent in about 10% of individuals that there is possibly no phylogenetic degenerative trend of the PL muscle in a South African population. In a South African population the prevalence of the PL muscle differs from studies done in the past. But like previously mentioned prevalence of this muscle does not guarantee the usefulness in reconstructive surgery, rather the morphology of this muscle