Morphometric analysis of the palmaris longus muscle: a fetal study

Objectives:The palmaris longus muscle is absent in 10-15% of forearms. Its long, flat tendon broadens as it passes in frontof flexor retinaculum, to which it is partly adherent. In the palm it splits to attach the longitudinally directed fibres of thepalmar aponeurosis. This fetus study is made to evaluate morphometric and topographic differences of adult and fetal palmaris longus muscle. Methods: The present study is carried out on 24 human fetuses aged 17-40 weeks of gestation. All upper limbs were carefully dissected with the aid of a stereomicroscope at 1.6x magnification. Digital calliper was used for all the measurements.Results: The palmaris longus muscles were absent in both forearms in 7 fetuses and in a unilateral forearm in 5 fetuses.Reversed palmaris longus muscle was found in 2 forearms. Most fetuses had a typical palmaris longus muscle and tendonshape. The mean length and width of the tendons were 18.42±9.55 and 0.66±0.37 mm, respectively, in second trimesterand, 25.9±13.90 and 1.71±0.95 mm in third trimester, respectively. The mean length and width of the muscular belly were13.33±7.05 and 2.03±1.04 mm, respectively, in second trimester and, 30.42±16.81 and 3.77±2.07 mm in third trimester,respectively. Conclusion:The results of our study show to more pronounced loss of the muscle on the left side. This detailed fetal studyin relationship to the palmaris longus muscle would be useful for educational anatomy dissections and surgical interventionsfor relevant clinical procedures