Anatomical Variations of Palmaris Longus Muscle and Its Clinical Implications: a Cadaveric Study

Palmaris longus (PL) is the most superficial flexor muscle of the anterior compartment of the forearm in humans, which exhibits frequent anatomical variance. It has been observed that the complete absence of PL is the most commonly reported variance, followed by reversed, duplicated and hypertrophied muscle variants. The incidence of the complete agenesis of PL varies from 0.6% to 26.6%. So, it may be considered as an inconstant muscle. It is known to be more commonly absent unilaterally than bilaterally. The prevalence of unilateral absence of the PL is more commonly found on the left side. Unilateral agenesis of the PL is relatively more widely encountered in males compared to females.

During the routine cadaveric dissections at the Department of Anatomy, AIIMS, Jodhpur, we observed palmaris longus muscle variations in 64 upper limbs of 32 cadavers (22 males and 10 females).

We observed agenesis of the palmaris longus muscle in six (9.4%) upper limbs out of 64 cadaveric upper limbs. The bilateral absence of palmaris longus was observed in two cadavers (6.25%), while unilateral absence was also observed in two cadavers (6.25%). We also observed agenesis of the PL was more prevalent in males (11.33%) in comparison to females (5%).

Palmaris longus is significant surgically as it is employed for various tendon graft procedures, lip augmentation, ptosis correction and management of facial palsy.