Arterial Supply of the Lower Limb

Vasculature of the Lower Limb

Objectives

• Understand the arterial supply to the lower limb.
• Identify the major arteries and their course.
• Appreciate the interconnected nature of the arterial network.
• Lay a foundation for understanding venous return and nervous innervation.

Systemic Circulation

• Systemic Circulation: A network of vessels delivering oxygen and nutrients to tissues and returning blood to the heart.
• Arterial Supply: Delivers oxygen and protein-rich blood.
• Venous Network: Returns blood deprived of oxygen and nutrients to the heart.
• Oxygen Importance: Essential for muscle and cell function, DNA transcription, and protein filament sliding.
• Protein Importance: Needed for cell and tissue preparation and function, including muscle contraction (actin and myosin).
• Neurotransmitters: Produced via proteins, essential for muscle function, growth, development, and repair.

Arterial Continuity and Naming Conventions

• Arteries and veins are continuous throughout their course.
• Names change based on location, landmarks, and branches.
• Example: Femoral artery (femoral region) vs. Anterior tibial artery (anterior tibial region).

Aorta and Bifurcation

• The aorta branches to supply the upper limb and head.
• It continues posteriorly through the thoracic cavity and penetrates the diaphragm to enter the abdominal cavity.
• Bifurcation: At the base of the false pelvis (iliac crest), the aorta splits into left and right branches.

Pelvic Vessels

• Blood is collected back into the pelvis through the venous network.
• Left and right pelvic veins join to form the inferior vena cava.
• The inferior vena cava enters the right atrium for pulmonary circulation and reoxygenation.

Pelvis Anatomy

• Landmark: The iliac crest marks the false pelvis.
• Abdominal Aorta: Enters the false pelvis and bifurcates at the iliac crest.
• Common Iliac Artery: Formed after the bifurcation of the abdominal aorta; splits into the external and internal iliac arteries.

Common Iliac Artery

• Definition: The vessel formed after the bifurcation of the abdominal aorta at the iliac crest.
• Right and Left: There are right and left common iliac arteries.
• Common Terminology: "Common" indicates that the vessel will branch further.

External and Internal Iliac Arteries

• External Iliac Artery: Continues externally down the leg.
• Internal Iliac Artery: Remains in the true pelvis, supplying muscles and tissues.
• Summary: Abdominal aorta bifurcates at the iliac crest into the common iliac artery, which then splits into the external and internal iliac arteries.

Internal Iliac Artery

• Location: Remains in the true pelvis.
• Branches:
  • Superior and Inferior Gluteal Arteries: Supply the gluteal muscles (gluteus maximus, minimus, medius) and tensor fascia lata.
    • Inferior gluteal artery supplies deep gluteal muscles (piriformis, tremella, obturator muscles).
  • Obturator Artery: Passes through the obturator canal/foramen and supplies muscles in the medial thigh compartment (adductor longus, brevis, magnus).
• Visceral Branches: Supply pelvic organs (uterus, bladder).

External Iliac Artery

• Path: Exits the pelvis and passes underneath the inguinal ligament in an anterior direction.
• Name Change: After passing under the inguinal ligament, it becomes the femoral artery.

Femoral Artery

Location: Enters the femoral region of the leg after passing under the inguinal ligament.

Femoral Triangle

• Definition: A depression on the anteromedial aspect of the groin.
• Borders:
  • Base: Inguinal ligament.
  • Medial Border: Adductor longus muscle.
  • Lateral Border: Sartorius muscle.
• Contents (medial to lateral):
  • Femoral Vein
  • Femoral Artery
  • Femoral Nerve
• Mnemonic: Vein, Artery, Nerve (from medial to lateral).
• Clinical Significance: Superficial access point for surgical procedures, angioscopes, and injections.

Femoral Artery Course

• Anterior Thigh: Supplies anterior thigh muscles (quadriceps: rectus femoris, vastus intermedius, medialis, and lateralis).
• Deep Femoral Artery (Profunda Femoris): Branch that runs deep to the posterior aspect of the leg; supplies posterior muscles (hamstrings: semitendinosus, semimembranosus, biceps femoris).
• Circumflex Artery: Circles around the head and neck of the femur to supply bone, knee, musculature, and lateral leg muscles.

Adductor Canal and Adductor Hiatus

• Adductor Canal: A nook between anterior (quadriceps) and adductor muscles for vessels to travel.
• Adductor Hiatus: A space in the adductor magnus tendon where the femoral artery passes through to the posterior aspect of the leg.

Popliteal Artery

• Formation: The femoral artery becomes the popliteal artery after passing through the adductor hiatus in the posterior aspect of the knee (popliteal region).
• Location: Posterior aspect of the knee.
• Branches: Genicular branches that wrap around the knee and supply the tissues in that region.

Tibial Arteries

• Bifurcation: At the distal aspect of the popliteal fossa, the popliteal artery branches into anterior and posterior tibial arteries.
• Anterior Tibial Artery:
  • Passes between the tibia and fibula through the interosseous membrane to the anterior aspect of the leg.
  • Supplies the anterior muscle compartment (tibialis anterior, extensor hallucis longus).
  • Continues down to form the dorsal pedis artery on the dorsal aspect of the foot.
• Posterior Tibial Artery:
  • Runs down the posterior aspect of the leg.
  • Supplies the posterior compartment muscles (gastrocnemius, soleus, flexor muscles).

Fibular Artery

• Branch: The posterior tibial artery branches into the fibular artery on the fibular (lateral) side of the leg.
• Supply: Supplies the lateral compartment muscles (fibularis longus and brevis).

Foot Arteries

• Dorsal Pedis Artery: Continuation of the anterior tibial artery on the dorsal aspect of the foot; terminates as the dorsal arch.
• Plantar Arteries: The posterior tibial artery goes down to the plantar aspect of the foot to form the plantar arch and plantar arteries.
• Arches: Lateral and medial arches connect to supply the digits of the posterior plantar aspect of the foot and toes.

Tarsal Tunnel

• Location: Where the posterior tibial artery enters the plantar aspect of the foot.
• Contents:
  • Tibialis posterior tendon
  • Flexor digitorum longus tendon
  • Posterior tibial artery
  • Posterior tibial vein
  • Tibial nerve
  • Flexor hallucis longus tendon
• Retinaculum: Flexor retinaculum protects and keeps the structures in place. Highly compacted contents in this region means compression is possible.
• Tarsal Tunnel Syndrome: Pain and altered sensations down the foot due to tibial nerve compression.