The authors attempt to redefine the anatomic origin of the tibialis posterior muscle, and correlate it with the location of medial tibial stress syndrome that occurs in the lower third of the tibia. Contrary to what is commonly described, the authors show on all ten dissected specimens, that the origin of the tibialis posterior does include a portion of the lower third of the tibia. The mean distance from tibialis posterior's origin to the medial malleolus was only 7.77 cm. In addition, to further explain lower leg pain, the authors investigated the crossing point of tibialis posterior and flexor digitorum longus; a mean distance for this to occur in the same ten specimens was 8.16 cm. proximal to the medial malleolus. These findings provide insight to anatomic reasons behind biomechanical factors responsible for medial tibial stress syndrome. This is also important to consider when performing surgery for a deep compartment syndrome.