Anterior Tibial Artery and Dorsum of the Foot
Originating from the popliteal artery at the lower border of the m. popliteus, the anterior tibial artery pierces the interosseous membrane and enters the anterior fascial compartment of the leg. It descends along the anterior surface of the membrane, supplying the muscles of the anterior compartment (with virtually no collateral vessels within the compartment). In its lower third, it is crossed anteriorly by the tendon of the extensor hallucis longus, so near the ankle joint, the vessel lies lateral to this tendon. The artery is accompanied by the deep fibular nerve (n. fibularis profundus).
After passing under the extensor retinaculum, the main vessel continues as the dorsalis pedis artery (a. dorsalis pedis). It lies directly on the tarsal bones (talus, navicular, and cuneiforms), allowing its pulse to be easily palpated. It gives off tarsal arteries, the arcuate artery (a. arcuata), and its most important terminal branch—the deep plantar branch (r. plantaris profundus)—which pierces the first intermetatarsal space to reach the sole.
Plantar Arteries
In the foot, the posterior tibial artery divides into two terminal branches that run in corresponding grooves alongside their companion nerves (the nerves are always lateral to the arteries).
- Medial plantar artery (a. plantaris medialis) — the smaller branch. It runs in the medial groove deep to the plantar aponeurosis, supplying the muscles of the abductor hallucis and the skin of the medial border of the foot. It does not participate in the formation of the plantar arch.
- Lateral plantar artery (a. plantaris lateralis) — the main vessel of the sole. It runs in the lateral groove and, at the base of the 5th metatarsal bone, curves sharply medially into the deep layer of the sole. Here, it anastomoses with the deep plantar branch of the dorsalis pedis artery to form the plantar arch (arcus plantaris profundus).
Four plantar metatarsal arteries arise from the plantar arch and subsequently divide into common and proper plantar digital arteries. Injuries in the projection of the lateral groove cause severe bleeding because the vessel is trapped between the bones and aponeurosis and cannot readily collapse.
Arterial Networks and Anastomoses
The vessels of the leg and foot form several critically important networks:
- Genicular articular network (rete articulare genus) — the primary collateral pathway around the popliteal artery, including branches from the femoral, popliteal, and tibial arteries.
- Malleolar networks (retia malleolaria) — medial and lateral. They serve to redirect blood flow between the anterior and posterior compartments of the leg during occlusion of one of the main trunks.
- Tarsal network (rete tarsi) — located on the bones of the foot, connecting the malleolar networks with the metatarsal vessels.
The dorsum and sole of the foot are reliably connected at three levels: via the deep plantar branch and the proximal and distal perforating branches (rr. perforantes). Thanks to this system, the foot can survive if at least one tibial artery remains patent.