Posterior tibial artery

The posterior tibial artery is a major blood vessel in the lower leg, branching from the popliteal artery. It supplies blood to the posterior compartment of the leg and foot.

Location

The posterior tibial artery originates in the lower leg at the level of the popliteal fossa, just below the knee. It travels down the posterior aspect of the leg, running deep to the soleus muscle. It descends along the medial side of the leg and passes posterior to the medial malleolus (the inner ankle bone). At the ankle, it divides into its terminal branches—the medial and lateral plantar arteries which supply blood to the foot. The artery runs alongside the tibial nerve and veins, accompanied by the posterior tibial vein.

Structure and Anatomy

Origin

The posterior tibial artery originates from the popliteal artery at the lower border of the popliteus muscle, just below the knee joint, in the popliteal fossa. It is one of the two terminal branches of the popliteal artery, the other being the anterior tibial artery. The posterior tibial artery emerges at the level of the proximal leg, within the posterior compartment.

Course

The posterior tibial artery descends through the deep posterior compartment of the leg, running parallel to the tibia. Initially, it is covered by the gastrocnemius and soleus muscles, then travels deeper to lie between the flexor digitorum longus and tibialis posterior muscles. As it moves downward, it remains in the posterior compartment of the leg and courses through the leg toward the medial ankle.

The artery travels downward and runs posterior to the medial malleolus of the tibia, within the tarsal tunnel. At this point, the posterior tibial artery is accompanied by the tibial nerve and posterior tibial veins, all of which are enclosed by the flexor retinaculum, a fibrous sheath that helps protect these structures as they pass behind the ankle.

Branches

The posterior tibial artery gives off several important branches throughout its course:

• Fibular (Peroneal) Artery: This artery is the largest and most significant branch of the posterior tibial artery. It arises in the upper third of the leg and runs along the lateral aspect of the posterior compartment, supplying the lateral and posterior compartments of the leg. Although it stays within the posterior compartment, it provides important perforating branches to the lateral compartment.
• Muscular Branches: These small branches arise along the course of the posterior tibial artery and supply the muscles of the posterior compartment, including the gastrocnemius, soleus, tibialis posterior, flexor digitorum longus, and flexor hallucis longus.
• Medial Malleolar Branch: Near the ankle, the posterior tibial artery gives off small branches that supply the medial side of the ankle, around the medial malleolus.
• Calcaneal Branches: These small branches arise as the artery passes near the heel, providing blood supply to the skin and structures over the heel.

Termination

The posterior tibial artery terminates at the level of the medial malleolus, where it divides into its two terminal branches:

• Medial Plantar Artery: This smaller branch supplies blood to the medial part of the sole of the foot and the big toe.
• Lateral Plantar Artery: The larger branch, which travels across the sole of the foot to form the deep plantar arch, supplies blood to the lateral aspect of the foot and toes.

Anatomical Relationships

The posterior tibial artery runs closely with several important structures in the leg and foot:

• Tibial Nerve: Throughout its course, the posterior tibial artery runs parallel to and is accompanied by the tibial nerve. Both structures travel through the tarsal tunnel, posterior to the medial malleolus, before branching in the foot.
• Posterior Tibial Veins: These veins accompany the posterior tibial artery along its entire length. They run in pairs (venae comitantes) on either side of the artery and drain the deep structures of the leg and foot.
• Tarsal Tunnel: As the artery passes behind the medial malleolus, it runs through the tarsal tunnel, a narrow space formed by the flexor retinaculum. The tarsal tunnel houses the posterior tibial artery, tibial nerve, and several tendons, such as the tibialis posterior, flexor digitorum longus, and flexor hallucis longus.

Size and Appearance

The posterior tibial artery is one of the larger arteries in the lower leg, following the tibia closely along its medial border. It is relatively long and supplies blood to a wide area of the lower leg and foot. The artery’s large size, along with its important branches, ensures that it plays a key role in the vascular supply of the lower extremity.

Surface Anatomy and Palpation

The posterior tibial artery is palpable behind the medial malleolus, where it runs superficially within the tarsal tunnel. Clinically, this is one of the key locations where the arterial pulse can be assessed in the lower limb, as it is easily accessible just beneath the skin.

Function

Primary Blood Supply to the Posterior Compartment of the Leg

The posterior tibial artery is the main source of oxygenated blood to the deep and superficial muscles of the posterior compartment of the leg. These muscles, which include the gastrocnemius, soleus, tibialis posterior, flexor digitorum longus, and flexor hallucis longus, play a crucial role in plantarflexion (pointing the toes downward) and inversion (turning the foot inward). By providing blood to these muscles, the posterior tibial artery supports their function in walking, running, and maintaining balance.

Supply to the Fibular (Lateral) Compartment

The posterior tibial artery indirectly supplies the lateral compartment of the leg through its major branch, the fibular (peroneal) artery. The fibular artery descends parallel to the fibula and provides perforating branches that supply the muscles in the lateral compartment, such as the fibularis longus and fibularis brevis. These muscles contribute to eversion (turning the foot outward) and plantarflexion of the foot, essential for lateral stability during movement.

Vascularization of the Medial Ankle and Foot

As the posterior tibial artery travels behind the medial malleolus, it provides several small branches to the medial malleolus and the calcaneal region. These branches ensure adequate blood supply to the skin, bones, and soft tissues around the ankle, including the heel. The calcaneal branches are responsible for nourishing the calcaneus (heel bone) and the surrounding structures, which endure significant pressure during standing, walking, and running.

Supply to the Sole of the Foot

One of the most important functions of the posterior tibial artery is its role in vascularizing the plantar surface of the foot. After passing through the tarsal tunnel, the artery divides into the medial plantar artery and the lateral plantar artery, which supply the skin, muscles, and bones of the sole. These arteries are essential for maintaining foot health and supporting the complex muscular actions required for standing, walking, and running.

• Medial Plantar Artery: This smaller branch of the posterior tibial artery supplies the medial portion of the sole, including the big toe, and provides blood to the abductor hallucis and flexor hallucis brevis muscles.
• Lateral Plantar Artery: The larger branch supplies the lateral aspect of the foot, including the abductor digiti minimi and flexor digitorum brevis muscles. It also forms part of the deep plantar arch, which is essential for blood supply to the metatarsals and toes.

Formation of the Deep Plantar Arch

The posterior tibial artery contributes to the formation of the deep plantar arch through its terminal branch, the lateral plantar artery. The deep plantar arch is a crucial vascular network in the foot that supplies blood to the metatarsals and the digital arteries, which in turn provide blood to the toes. This arch is formed by the anastomosis (connection) between the lateral plantar artery and the deep branch of the dorsalis pedis artery from the dorsal side of the foot. The deep plantar arch ensures that the foot and toes receive an adequate blood supply, particularly during movement and weight-bearing activities.

Role in Collateral Circulation

The posterior tibial artery plays a significant role in collateral circulation in the lower leg and foot. Collateral circulation refers to the network of smaller arteries that provide alternate routes for blood flow in case of blockage or damage to a major artery. The posterior tibial artery, through its branches and anastomoses with other arteries (such as the fibular artery and anterior tibial artery), helps maintain continuous blood supply to the leg and foot, even when the primary arterial pathways are compromised.

Oxygenation and Nutrient Supply to the Leg and Foot

By delivering oxygenated blood, the posterior tibial artery ensures that all the tissues in the posterior leg and foot—skin, muscles, tendons, bones, and nerves—receive the necessary oxygen and nutrients for cellular function and repair. Proper oxygenation supports muscle contraction, wound healing, and the health of weight-bearing structures, such as the bones of the ankle and foot. This is especially important for maintaining endurance and preventing fatigue or tissue damage during prolonged physical activities.

Maintenance of Tissue Viability

The posterior tibial artery’s extensive vascularization of the posterior leg and foot prevents ischemia, a condition where tissues become deprived of oxygen due to inadequate blood flow. This artery is critical in maintaining tissue viability, especially in the foot, where continuous blood supply is essential to avoid complications like tissue necrosis, particularly in conditions like diabetes or peripheral artery disease (PAD).

Pulse Assessment and Clinical Indicator of Circulation

The posterior tibial artery’s location behind the medial malleolus makes it an important site for pulse assessment. Clinically, the posterior tibial pulse is commonly used to evaluate blood flow to the lower extremity. The presence of a strong, palpable pulse indicates good circulation, while a weak or absent pulse may suggest arterial disease or other circulatory issues affecting the leg and foot.

Clinical Significance

The posterior tibial artery plays a vital role in maintaining blood supply to the posterior compartment of the leg and the plantar surface of the foot. Its clinical significance is most apparent in cases of peripheral artery disease (PAD), where reduced blood flow through the artery can lead to ischemia, particularly in the foot. A weak or absent posterior tibial pulse is a key diagnostic sign of arterial insufficiency and poor circulation in the lower limb, often assessed during physical exams.

In conditions like diabetic foot ulcers and chronic limb ischemia, the posterior tibial artery’s blood supply is critical for wound healing and preventing tissue necrosis. Surgeons often use the posterior tibial artery as a reference during reconstructive surgeries or vascular grafting procedures to restore circulation. Additionally, trauma to the lower leg or foot can result in damage to the artery, leading to complications such as compartment syndrome or delayed healing of fractures.