The palmaris longus (PL) muscle is a superficial flexor muscle that exhibits a notable anatomical variability and is frequently used in reconstructive surgery. Its absence or morphological differences may influence surgical planning. This study aims to determine the prevalence and morphological variation of PL in the Jordanian population, and assess its relationship with sex, hand dominance and parental origin. A cross-sectional study of 403 University of Jordan students was conducted. PL presence was assessed bilaterally using multiple tests (Schaeffer’s, Thompson’s, Mishra’s test I and II, and Pushpakumar’s tests). Photographs of the forearm were taken and independently reviewed to classify the PL morphology into normal, bifurcated, radial deviation, ulnar deviation, reversed, or absent.
PL was present bilaterally in 228 participants (56.5%), absent bilaterally in 92 (22.8%), and unilaterally absent in 83 (20.6%). Unilateral absence was more frequent in the left (12.9%) than the right (7.7%). Sex was significantly associated with PL presence, while parental origin (mother’s origin), (father’s origin) and hand dominance were not. Most Jordanians in this study had bilaterally present PL, with notable morphological diversity. Females were more likely to have an absent PL than males, whereas hand dominance and parental origin did not influence its presence. The novel classification of PL variations proposed here may assist surgeons in preoperative evaluation for tendon grafting.
