Abstract:
The literature reports that the palmaris longus muscle (PL) is only found in
mammals in which the forelimbs are weight-bearing extremities. It is suggested
that the function of this muscle has been taken over by the other flexors
in the forearm. Terms used in the literature to describe the diminishing of
this muscle include retrogressive or phylogenetic degenerative trends. The
aims of this study were to determine the prevalence of PL in a South African
population and whether a phylogenetic degenerative trend for the PL exists. To
determine the prevalence of the PL, five groups, representing different age
intervals (Years 0–20, 21–40, 41–60, 61–80, and 81–99) were used. A sample
of 706 participants of various ages was randomly selected. 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 phylogenetic degenerative trend of PL within the
five groups. The sample yielded a bilateral absence of the PL in 11.9% of the
cases. The muscle was unilaterally absent on the left side in 7.65% and 6.94%
on the right side. The Chi-squared tests revealed a P-value of 0.27 for the left
arm and 0.39 for the right arm. No obvious trend could be established for the
phylogenetic degeneration of the PL in this study. It would appear that the PL
muscle should not be considered as a phylogenetically degenerating muscle in
a South African population.
