The prevalence of absence of the palmaris longus muscle in the Bahraini population.

Absence of the palmaris longus muscle has been well documented in several populations at a prevalence rate ranging between 2.2 and 63.9% which varies according to race, sex, and side of the body. There is little documentation of the prevalence of absence of this muscle from populations in the Arabian Gulf region. We examined 1,043 subjects, 3-85 years old, from the Kingdom of Bahrain for the presence or absence of the palmaris longus muscle using the conventional test for the presence of this muscle. Statistical analyses investigated the association of muscle absence with sex, hand dominance, and laterality. The palmaris longus muscle was absent in 36.8% of subjects. Bilateral absence (19%) was more common than unilateral absence (17.9%) with preponderance in female subjects. The muscle was absent more often on the left side than the right (P = 0.003). In the right upper limbs the muscle was absent in female subjects more than male subjects (P = 0.031). This study reaffirms that there is population variation in the frequency of absence of the palmaris longus muscle. The tendon of the palmaris longus bifurcated at the wrist in 7.1% of subjects, with male subjects showing this feature more frequently than female subjects in the right hand (P = 0.037) and the left hand (P = 0.030). This has not been reported before. The clinical significance of our findings is discussed.