The plantaris muscle and tendon may be regarded as the vestigial remains of a primitive flexor muscle of the toes, which, originally continuous with the plantar aponeurosis, later was rendered discontinuous through intermediate attachment to the calcaneum.
The plantaris muscle and its tendon are subject to considerable variation in both the points of origin and of insertion. In an examination of 150 lower extremities, the authors have encountered four types of insertion of the tendon.
In 750 consecutive lower extremities examined by the present authors, the plantaris muscle was absent in fifty (6.67 per cent.). In one-third of the specimens in which the muscle was missing, the absence was bilateral.
The surgical utilization of the plantaris tendon is particularly indicated as a desirable substitute for the fascia lata in hernial repair, tendon transplants, and repair of ligaments.