Phylogenetic variation in flexor digitorum brevis: a Nepalese cadaveric study

Understanding muscle architecture of the foot may assist in the design of surgical procedures such as tendon transfer, biomechanical modeling of the foot, prosthesis design, and analysis of foot function. Flexor digitorum brevis (FDB) is the most superficial intrinsic muscle of the sole of the foot. When compared to the little finger, the little toe has less function and opposition is absent in humans. Hence, the muscles acting on the little toe are undergoing evolutionary changes. The objective of this study was to review the phylogenetic variation occurring in FDB in the Nepalese cadavers. Sixty soles in 20 male and 10 female adult embalmed cadavers were dissected and attachments of FDB observed. It was noted that the tendon for the fifth toe was missing in all sixty soles. The action of FDB can be compensated by other long flexors of the foot. This could have resulted due to gradual reduction in the usage of the little toe as the bipedal posture evolved. Variations of FDB are clinically important because FDB musculocutanous flap is used in the reconstruction of the heel pad.