Lower Limb Anatomy and Functions

Lower Limb Anatomy

• The lower limb consists of the gluteal, thigh, leg, and foot regions.
• The femoral triangle, popliteal fossa, and tarsal tunnel are important transition areas in the lower limb.

Functions of the Lower Limb

• The lower limb supports body weight and facilitates locomotion and balance.

Pelvic Bones

• The pelvic bone is irregular in shape and composed of the ilium, pubis, and ischium.
• The ilium is the largest and upper portion of the pelvic bone.
• The pubis is the anterior part of the pelvic bone.
• The ischium is the posterior and inferior part of the pelvic bone.

Femur

• The femur is the longest and strongest bone in the body.
• It consists of a head, neck, greater trochanter, lesser trochanter, shaft, medial epicondyle, lateral epicondyle, medial condyle, and lateral condyle.

Deep Fascia of the Thigh

• The deep fascia of the thigh is called the fascia lata.
• It is a strong, stocking-like structure that limits the outward extension of contacting muscles, facilitating efficient muscle contraction and venous compression.
• The fascia lata is thickened laterally, forming the iliotibial tract (IT tract).
• The IT tract extends from the tuberculum of iliac crest to just below the knee.
• The tensor fascia lata and gluteus maximus muscles attach to the IT tract and help hold the leg in extension.

Superficial Veins of the Leg

• Great saphenous vein: originates on medial side of the dorsal venous arch, passes anterior to the medial malleolus, ascends along the medial side of the leg, knee, and thigh, and drains into the femoral vein.
• Small saphenous vein: originates on the lateral side of the dorsal venous arch, passes posterior to the lateral malleolus, ascends in the posterior leg, and drains into the popliteal vein.

Varicose Veins

• Varicose veins are dilated, elongated, and tortuous superficial veins with incompetent or absent valves.
• Valves in healthy veins prevent backward blood flow.
• Varicose veins result from blood pooling in superficial veins due to valve incompetence.
• Common locations for varicose veins: superficial veins of the legs due to high pressure when standing (great saphenous vein).
• Symptoms include pain, leg swelling, skin thickening, and ulceration.
• Treatment options include vein obliteration, support stockings, leg elevation, and exercise regimens.

Muscles and Movement

• Muscles passing at least one joint will work on that joint.
• Multiple muscles contribute to any movement.
• Prime movers: muscles primarily responsible for a movement.
• Antagonists: muscles with the opposite action of a muscle.
• Synergists: muscles that assist prime movers.

Anterior Compartment of the Thigh

• Muscles: quadriceps group (extensors of the leg), iliopsoas (flexor of the trunk/hip), sartorius (flexes thigh and leg), and tensor fascia lata.
• Innervation: femoral nerve (except tensor fascia lata).
• Key muscles:
  • Quadriceps femoris group:
    • Rectus femoris: extends the leg at the knee and flexes the thigh at the hip.
    • Vastus lateralis: extends the leg at the knee.
    • Vastus medialis: extends the leg at the knee.
    • Vastus intermedius: extends the leg at the knee.
  • Iliopsoas: flexes the thigh at the hip (most powerful flexor).
  • Sartorius: flexes the thigh at the hip and flexes the leg at the knee, abducts and laterally rotates the thigh.
  • Tensor fascia lata: abducts and medially rotates the thigh.

Medial Compartment of the Thigh

• Muscles: adductors of the thigh (adductor longus, adductor brevis, adductor magnus, gracilis, and pectineus).

• Innervation: obturator nerve (except pectineus and hamstring part of adductor magnus).

• Key muscles:

  • Pectineus: adducts and flexes the thigh.
  • Adductor longus: adducts and medially rotates the thigh.
  • Adductor brevis: adducts and medially rotates the thigh.
  • Adductor magnus: adducts and medially rotates the thigh.
  • Gracilis: adducts the thigh, flexes the leg, and medially rotates the leg.

Femoral Triangle

• Boundaries: inguinal ligament (superior), sartorius (medial), and adductor longus (lateral).
• Contents: femoral nerve, femoral artery, femoral vein, and deep inguinal lymph nodes.
• Main branches of femoral artery:
  • Deep (profunda) artery of the thigh: main artery of the anterior compartment, giving off lateral and medial circumflex femoral branches, and perforating branches (penetrate adductor magnus).
  • Superficial epigastric artery: supplies the superficial abdominal wall.
  • Superficial circumflex iliac artery: supplies the superficial gluteal region.
  • External pudendal arteries: supply the external genitalia.

Obturator Artery

• The main artery of the medial compartment, branching from the internal iliac artery.

Deep Veins

• The deep veins of the lower limb include the tibial veins, popliteal vein, femoral vein, external iliac vein, common iliac vein, and inferior vena cava (IVC).

Deep Venous Thrombosis (DVT)

• DVT occurs when a blood clot (thrombus) forms in a deep vein.
• Causes: inactivity, injury, or other conditions that can slow blood flow.
• Risks: potentially dangerous as clots can break off (emboli) and travel to the lungs.
• Symptoms: swelling, pain, and warmth in the affected leg.
• Treatment: anticoagulant medications, blood thinners, and compression stockings.

Lymphatics

• Superficial inguinal lymph nodes: drain lymph from the lower limb, external genitalia, and abdominal wall.

Clinical Examination

• Testing the Quadriceps Group:
  • Practitioner applies resistance to the leg during extension while observing for compensatory movement.
  • The practitioner should examine for leaning backwards, recruiting hip flexors, or solely using the rectus femoris muscle.
• Femoral Triangle:
  • Clinical landmarks: inguinal ligament, sartorius muscle, and adductor longus muscle.
  • Femoral pulse: palpable in the femoral triangle, just inferior to the inguinal ligament.

Radiological Imaging

• Radiographs: used to visualize the bones of the thigh and pelvis.
• Ultrasound: used to visualize the vessels of the thigh and pelvis.

Explore the anatomy of the lower limb, including key regions like the femoral triangle and pelvic bones. Learn about the structure and functions of the femur, as well as the role of the lower limb in supporting weight and facilitating movement.