Posterior tibial artery

Course

The posterior tibial artery arises as a terminal branch of the popliteal artery between the tibia and fibula at the level of the lower margin of the popliteus muscle. It takes an inferomedial course, descending through the posterior (flexor) compartment of the leg. The artery enters the foot by passing inferiorly to the medial malleolus. Midway between the malleolus and the tubercle of calcaneus, it ends by splitting into the lateral and medial plantar arteries.

Relations

The proximal part of the posterior tibial artery lies deep to the gastrocnemius and soleus muscles. As it descends through the leg, the artery courses over the posterior surfaces of the tibialis posterior, flexor digitorum longus, tibia and the ankle joint. The distal part of the artery is more superficial, coursing underneath the skin. At the ankle level, the artery runs parallel and anterior to the calcaneal tendon. It then traverses the tarsal tunnel, deep to the flexor retinaculum, entering the plantar compartment of the foot. The terminal bifurcation of the posterior tibial artery is located deep to the adductor hallucis muscle.

The two posterior tibial veins accompany the artery. The artery is also in relation to the tibial nerve. The nerve crosses the posterior side of the artery’s origin and is located medial to the artery along its course. At the level of the flexor retinaculum, the tibial artery is found posterior to the veins and anterior to the posterior tibial nerve (branch of the tibial nerve). A handy mnemonic to remember their relations going anteroposteriorly is VAN (Veins-Artery-Nerve).

Branches and supply

The posterior tibial artery has ten branches in total; circumflex fibular, nutrient, muscular, perforating, communicating, medial malleolar, calcaneal, fibular, lateral plantar and medial plantar arteries.

• The circumflex fibular artery arises immediately after the origin of the posterior tibial artery. It surrounds the neck of fibula and anastomoses with the inferior medial and lateral genicular and anterior tibial recurrent arteries. It supplies the proximal end of fibula.
• The fibular artery arises approximately 2.5cm after the posterior tibial artery arises, distal to the popliteal muscle, where it descends along the medial aspect of the fibula. Read more about this artery here. The proximal part of the posterior tibial artery as far as where the fibular artery branches off is often referred to as the tibiofibular trunk (or tibioperoneal trunk).
• The nutrient artery of tibia arises distally to the circumflex fibular artery. It enters the tibia below the soleal line, being the main vessel that supplies this bone.
• The muscular branches stem serially from the trunk of the artery and serve for vascularization of the soleus muscle and the deep flexors of the leg; popliteus, flexor hallucis longus, flexor digitorum longus and tibialis posterior.
• The perforating branches arise between the soleus and flexor digitorum longus muscle. There are usually five of them, each dividing into anterior and posterior divisions that together supply the skin and fascia of the posterior leg.
• The communicating branch emerges above the distal end of tibia deep to flexor hallucis longus muscle. It anastomoses with the communicating branch of the fibular artery. 
• The medial malleolar branches surround the medial malleolus and contribute to the medial malleolar vascular network, via which they supply the skin of this area.
• The calcaneal branches arise just proximally to the terminal bifurcation of the posterior tibial artery. They perforate the flexor retinaculum and supply the skin over the calcaneal tendon and calcaneus, and the muscles of the medial part of the sole of the foot. They anastomose with medial malleolar arteries and calcaneal branches of the fibular artery.

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