Variations in the insertion of peroneus longus muscle

Abstract

Introduction: Peroneus longus (PL) in man assumes special significance as it helps in maintaining the foot in plantigrade position and simultaneously maintains the arched character of foot. During evolution, insertion of PL has migrated from the lateral border of foot to reach its medial border, through the deep part of sole, getting purchase on the contiguous parts of lateral surface of the medial cuneiform and base of 1st metatarsal in its lower part. Hence, it was expected that some interesting variations in the insertion of PL may be found. Methods: Thirty-eight (38) feet from 19 adult embalmed cadavers, without any deformity of foot, were utilized for this study. Soles were dissected to expose the distal part of tendon of PL from the lateral margin of foot up to its insertion. Results: PL tendon at its insertion showed interesting variations in about 61% cases. In 23% feet, the tendon flared out into a triangular expansion, and in half of them, it received a slip from the tendon of tibialis posterior (TP) along its proximal border. The main tendon of TP was superior to the triangular expansion. In 8% specimens, a tendinous slip from the tendon of PL, near its insertion, continued with first dorsal interosseous muscle. Conclusion: Variations of PL muscle are more common than they are supposed. Findings of this work will be of interest to the morphologist and of great help to the orthopedicians in correcting the foot deformities.