During the 14 mm stage of embryonic development, one of the branches of the deep popliteal artery descends through the posterior crural region, resembling the adult posterior tibial artery (Senior 1919). The other branch arises more distally and is the posterior superficial fibular artery. The former passes backward along the medial side of the tibialis nerve to reach the posterior aspect of the leg and then descends along the posterior aspect of the nerve until it enters the sole of the foot, becoming the medial plantar artery in the adult (Senior 1919). The latter passes from the medial to lateral aspect of the tibial nerve, traveling anterior and lateral to the nerve until it forms branches that end blindly (Senior 1919). At the 17.8 mm stage, the portion of the posterior superficial tibial artery between the popliteal artery and the origin of the lateral plantar artery becomes the adult posterior tibial artery. During the 18 mm stage, behind the medial malleolus, the posterior superficial tibial artery finds its relationship between the tibial artery and the flexor hallucis longus (Senior 1919). At the 24.5 mm stage, the proximal portion of this artery blends with the corresponding section of the posterior superficial fibular artery as far as the termination of the popliteal artery, forming the adult posterior tibial artery (Senior 1919).