Arteries Of The Lower Limb Anatomy

The arterial supply of the lower limb is a complex and vital network, responsible for delivering oxygenated blood to the muscles, bones, and tissues that enable movement, sensation, and overall function. Understanding the anatomy of these arteries is crucial for diagnosing and treating vascular diseases, planning surgical procedures, and interpreting imaging studies.

The Major Arteries

The arterial supply to the lower limb originates from the external iliac artery, which becomes the femoral artery as it passes under the inguinal ligament. From there, it branches into a complex network that extends down to the foot. These main arteries include:

• External Iliac Artery: The direct continuation of the common iliac artery, supplying the lower limb.
• Femoral Artery: The main artery of the thigh, branching from the external iliac artery.
• Popliteal Artery: A continuation of the femoral artery behind the knee.
• Anterior Tibial Artery: Arises from the popliteal artery and supplies the anterior compartment of the leg and the dorsum of the foot.
• Posterior Tibial Artery: Also a branch of the popliteal artery, supplying the posterior compartment of the leg and the plantar aspect of the foot.
• Fibular (Peroneal) Artery: Arises from the posterior tibial artery and supplies the lateral compartment of the leg.
• Dorsalis Pedis Artery: A continuation of the anterior tibial artery on the dorsum of the foot.
• Plantar Arteries (Medial and Lateral): Branches of the posterior tibial artery in the foot, supplying the plantar aspect.

Let's delve into each of these arteries, tracing their paths and exploring their key branches.

External Iliac Artery: The Origin

The external iliac artery is the lifeline of the lower limb, originating as a direct continuation of the common iliac artery. It begins at the bifurcation of the common iliac artery, around the level of the L5 vertebra, and travels inferiorly and laterally along the pelvic brim. Its primary role is to supply blood to the lower limb.

Key Anatomical Landmark: As the external iliac artery passes under the inguinal ligament, it transitions into the femoral artery. This point marks the boundary between the abdominal and lower limb arterial systems.

Branches: The external iliac artery gives off two notable branches within the pelvis:

1. Inferior Epigastric Artery: Ascends along the anterior abdominal wall, supplying the rectus abdominis muscle and contributing to the collateral circulation.
2. Deep Circumflex Iliac Artery: Runs along the iliac crest, supplying the abdominal muscles and iliac bone.

These branches are important for collateral circulation, providing alternative pathways for blood flow in case of obstruction in the main arteries.

Femoral Artery: The Main Artery of the Thigh

Once the external iliac artery passes under the inguinal ligament, it becomes the femoral artery. This is the principal artery of the thigh, running down the anterior compartment. It's a relatively superficial artery, making it accessible for palpation and catheterization.

Course: The femoral artery descends through the femoral triangle, a region defined by the inguinal ligament, sartorius muscle, and adductor longus muscle. It then enters the adductor canal (subsartorial canal or Hunter's canal), a passageway within the thigh muscles. After exiting the adductor canal through the adductor hiatus, it becomes the popliteal artery behind the knee.

Branches: The femoral artery gives off several important branches:

1. Superficial Epigastric Artery: Supplies the superficial tissues of the lower abdomen.
2. Superficial Circumflex Iliac Artery: Supplies the superficial tissues around the iliac crest.
3. Superficial External Pudendal Artery: Supplies the skin of the scrotum or labia majora.
4. Deep External Pudendal Artery: Supplies the scrotum or labia majora and the medial thigh.
5. Profunda Femoris (Deep Femoral) Artery: The largest branch of the femoral artery, providing the primary blood supply to the thigh muscles.
6. Descending Genicular Artery: Arises near the end of the adductor canal and contributes to the genicular anastomosis around the knee.

The Profunda Femoris Artery

The profunda femoris artery (deep femoral artery) is a major branch of the femoral artery and is crucial for supplying the thigh muscles. It arises from the lateral side of the femoral artery, a few centimeters below the inguinal ligament.

Branches: The profunda femoris artery gives off several branches:

1. Lateral Circumflex Femoral Artery: Wraps around the femur laterally, supplying the hip joint, the greater trochanter, and the lateral thigh muscles. It has ascending, transverse, and descending branches.
2. Medial Circumflex Femoral Artery: Wraps around the femur medially, supplying the hip joint and the medial thigh muscles. It is particularly important for the blood supply to the femoral head.
3. Perforating Arteries (usually 3-4): Pierce the adductor magnus muscle and supply the posterior thigh muscles (hamstrings). They also contribute to the collateral circulation of the lower limb.

The profunda femoris artery and its branches are essential for the function and health of the thigh muscles and hip joint.

Popliteal Artery: Behind the Knee

The popliteal artery is the continuation of the femoral artery as it passes through the adductor hiatus and enters the popliteal fossa (the area behind the knee). This artery is deeply situated and vulnerable to injury in knee dislocations.

Course: The popliteal artery runs vertically through the popliteal fossa, passing between the hamstring tendons superiorly and the gastrocnemius muscle inferiorly. It lies on the posterior surface of the knee joint capsule.

Branches: The popliteal artery gives off several genicular branches that form an anastomosis (a network of interconnected vessels) around the knee joint. This anastomosis is important for maintaining blood flow to the leg in case of obstruction of the main arteries.

1. Superior Medial Genicular Artery: Supplies the medial aspect of the knee joint.
2. Superior Lateral Genicular Artery: Supplies the lateral aspect of the knee joint.
3. Middle Genicular Artery: Pierces the posterior knee joint capsule and supplies the ligaments and synovial membrane within the joint.
4. Inferior Medial Genicular Artery: Supplies the medial aspect of the knee joint.
5. Inferior Lateral Genicular Artery: Supplies the lateral aspect of the knee joint.
6. Sural Arteries (Gastrocnemius Arteries): Supply the gastrocnemius and soleus muscles in the calf.

At the lower border of the popliteus muscle, the popliteal artery divides into the anterior tibial artery and the posterior tibial artery.

Anterior Tibial Artery: Supplying the Anterior Leg and Foot

The anterior tibial artery is one of the two terminal branches of the popliteal artery. It supplies the anterior compartment of the leg, which contains the tibialis anterior, extensor hallucis longus, extensor digitorum longus, and fibularis (peroneus) tertius muscles.

Course: The anterior tibial artery passes forward through a gap in the interosseous membrane (the fibrous sheet connecting the tibia and fibula) and descends along the anterior aspect of the leg, between the tibialis anterior and extensor hallucis longus muscles.

Branches:

1. Posterior Tibial Recurrent Artery: Ascends to participate in the genicular anastomosis around the knee.
2. Anterior Tibial Recurrent Artery: Ascends to participate in the genicular anastomosis around the knee.
3. Anterior Malleolar Arteries (Medial and Lateral): Supply the ankle joint and surrounding structures.

As the anterior tibial artery crosses the ankle joint, it becomes the dorsalis pedis artery on the dorsum (top) of the foot.

Posterior Tibial Artery: Supplying the Posterior Leg and Foot

The posterior tibial artery is the larger of the two terminal branches of the popliteal artery. It supplies the posterior compartment of the leg, which contains the gastrocnemius, soleus, tibialis posterior, flexor hallucis longus, and flexor digitorum longus muscles.

Course: The posterior tibial artery descends along the posterior aspect of the leg, deep to the gastrocnemius and soleus muscles. It passes posterior to the medial malleolus (the bony prominence on the inside of the ankle) and enters the foot.

Branches:

1. Fibular (Peroneal) Artery: A major branch that supplies the lateral compartment of the leg.
2. Nutrient Artery to the Tibia: Enters the tibia to supply its bone marrow.
3. Communicating Branch to the Fibular Artery: Connects the posterior tibial and fibular arteries.
4. Medial Malleolar Arteries: Supply the ankle joint and surrounding structures.
5. Calcaneal Branches: Supply the heel.

Behind the medial malleolus, the posterior tibial artery divides into the medial plantar artery and the lateral plantar artery, which supply the plantar aspect (sole) of the foot.

The Fibular (Peroneal) Artery

The fibular (peroneal) artery is a significant branch of the posterior tibial artery that supplies the lateral compartment of the leg, containing the fibularis longus and fibularis brevis muscles.

Course: The fibular artery descends along the medial side of the fibula, within the lateral compartment of the leg.

Branches:

1. Nutrient Artery to the Fibula: Enters the fibula to supply its bone marrow.
2. Communicating Branch to the Posterior Tibial Artery: Connects the fibular and posterior tibial arteries.
3. Perforating Branches: Pierce the interosseous membrane to communicate with the anterior tibial artery.
4. Lateral Calcaneal Branches: Supply the heel.

The fibular artery plays a crucial role in supplying the lateral leg and contributes to the collateral circulation around the ankle.

Dorsalis Pedis Artery: The Artery on the Top of the Foot

The dorsalis pedis artery is the continuation of the anterior tibial artery as it crosses the ankle joint and enters the dorsum of the foot. It's a relatively superficial artery, making it easily palpable. Assessing the dorsalis pedis pulse is a common clinical practice to evaluate the arterial supply to the foot.

Course: The dorsalis pedis artery runs along the dorsum of the foot, between the extensor hallucis longus tendon and the extensor digitorum longus tendons.

Branches:

1. Lateral Tarsal Artery: Supplies the lateral aspect of the tarsus (the bones of the midfoot).
2. Medial Tarsal Arteries: Supply the medial aspect of the tarsus.
3. Arcuate Artery: Runs laterally across the bases of the metatarsal bones, giving off dorsal metatarsal arteries to the toes.
4. Deep Plantar Artery: Pierces the sole of the foot between the first and second metatarsal bones to join the plantar arch.

The dorsalis pedis artery is vital for supplying blood to the dorsum of the foot and contributes to the overall blood supply to the toes.

Plantar Arteries: Supplying the Sole of the Foot

The medial and lateral plantar arteries are the terminal branches of the posterior tibial artery, supplying the plantar aspect (sole) of the foot.

Course: After passing behind the medial malleolus, the posterior tibial artery divides into the medial and lateral plantar arteries.

1. Medial Plantar Artery: Runs along the medial side of the sole, supplying the skin and muscles of the medial aspect of the foot.
2. Lateral Plantar Artery: The larger of the two, runs laterally across the sole and forms the plantar arch.

The Plantar Arch

The plantar arch is formed primarily by the lateral plantar artery, which is joined by the deep plantar artery (a branch of the dorsalis pedis artery). This arch provides a major source of blood supply to the toes.

Branches:

1. Plantar Metatarsal Arteries: Arise from the plantar arch and run along the metatarsal bones.
2. Plantar Digital Arteries: Arise from the plantar metatarsal arteries and supply the toes.

The plantar arch and its branches ensure a rich blood supply to the sole of the foot, essential for its function and sensation.

Anastomoses: Ensuring Collateral Circulation

Anastomoses are connections between different arteries, providing alternative pathways for blood flow in case of obstruction. The lower limb has several important anastomoses that help maintain blood supply to the tissues. Key areas of anastomosis include:

• Around the Hip Joint: Involving the lateral and medial circumflex femoral arteries and branches from the internal iliac artery.
• Around the Knee Joint (Genicular Anastomosis): Formed by the genicular branches of the femoral and popliteal arteries.
• Around the Ankle Joint: Involving branches of the anterior and posterior tibial arteries, as well as the fibular artery.
• In the Foot: Between the dorsalis pedis artery and the plantar arteries, forming the plantar arch.

These anastomoses are crucial for maintaining blood flow to the lower limb, especially in individuals with peripheral artery disease (PAD).

Clinical Significance

Understanding the anatomy of the arteries of the lower limb is essential for diagnosing and treating various vascular conditions, including:

• Peripheral Artery Disease (PAD): A common condition in which the arteries of the lower limb become narrowed or blocked, typically due to atherosclerosis. This can lead to leg pain (claudication), foot ulcers, and, in severe cases, amputation.
• Acute Limb Ischemia: A sudden blockage of an artery in the lower limb, which can lead to tissue damage and limb loss if not treated promptly.
• Aneurysms: Abnormal bulges in the wall of an artery, which can rupture and cause life-threatening bleeding. Popliteal artery aneurysms are relatively common.
• Vascular Trauma: Injuries to the arteries of the lower limb due to trauma, such as fractures or dislocations.

Knowledge of the arterial anatomy is also crucial for planning surgical procedures, such as arterial bypass grafting or angioplasty, to restore blood flow to the lower limb.

Imaging Techniques

Several imaging techniques are used to visualize the arteries of the lower limb:

• Duplex Ultrasound: A non-invasive technique that uses sound waves to assess blood flow in the arteries.
• Computed Tomography Angiography (CTA): A CT scan with intravenous contrast dye to visualize the arteries.
• Magnetic Resonance Angiography (MRA): An MRI scan with intravenous contrast dye to visualize the arteries.
• Conventional Angiography: An invasive procedure in which a catheter is inserted into an artery and contrast dye is injected to visualize the arteries on X-ray.

These imaging techniques help clinicians diagnose vascular diseases, plan treatments, and monitor the results of interventions.

Conclusion

The arterial supply of the lower limb is a complex and interconnected network that is essential for its function and health. Understanding the anatomy of these arteries, including their origins, courses, branches, and anastomoses, is crucial for diagnosing and treating vascular diseases and planning surgical procedures. From the external iliac artery to the plantar arteries, each vessel plays a vital role in delivering oxygenated blood to the muscles, bones, and tissues of the lower limb, enabling movement, sensation, and overall well-being.