Palmaris longus, phylogenetically a retrogressive muscle, exhibits significant anatomical variations compared to other muscles of the upper extremity.

The palmaris longus is seen as a small tendon between the flexor carpi radialis and the flexor carpi ulnaris, although it is not always present. The muscle is absent in about 14 percent of the population, however this number varies greatly in African, Asian, and Native American populations.

Absence of this muscle does not have an effect on grip strength.

The palmaris longus muscle can be palpated by touching the pads of the fifth finger and thumb whilst flexing the wrist. The tendon, if present, will be visible in the midline of the anterior wrist.

It is of great surgical importance because, it is the first option tendon for graft procedures in various cosmetic, plastic and reconstructive surgeries. It has also been widely used in various tendon transfer procedures in treating facial paralysis, ptosis correction, lip augmentation and digital pulley reconstruction.

Iqbal et al. report a rare variant pattern of Palmaris longus with duplicated tendons and with multiple insertions to thenar and hypothenar muscles, fasciae and the flexor retinaculum along with its normal continuation as palmar aponeurosis. Variations in its insertions not only contribute, but also augment the various pathological processes such as Dupuytren's contracture, Carpal tunnel and Guyon's syndromes. So it is of utmost importance for surgeons, physicians and radiologists, to be aware of these variations, well in advance ¹⁾.