Gross Anatomy of the Leg

Gross Anatomy of the Leg

• Learning Objectives: Students should be able to describe the leg's osteology, the muscles of its compartments (anterior, posterior, and lateral), blood and nerve supply, and the popliteal fossa.
• Introduction: The leg is the region of the lower limb between the knee and ankle joints.
• Bones: The leg consists of the tibia and fibula.
  • Tibia: The primary weight-bearing bone.
  • Fibula: Provides attachment for muscles and supports ankle stability.
  • Tibia articulates with femur superiorly and talus inferiorly for weight transmission.
  • Fibula connects to tibia by interosseous membrane.

Tibia

• Key Features:
  • Medial condyle: Supports femur's medial condyle, and provides insertion for semimembranosus muscle.
  • Lateral condyle: Supports femur's lateral condyle,
  • Tibial tuberosity: Insertion point for the patellar ligament.
  • Border of interosseous membrane: Medial attachment point of the interosseous membrane.
  • Nutrient foramen: Small hole for blood vessels on the tibia's posterior surface.
  • Soleal line: Rough ridge on posterior surface for soleus muscle origin.

Fibula

• Key Features:
  • Head: Articulates with the tibia's lateral condyle and provides insertion point for fibular collateral ligament and biceps femoris.
  • Neck: Where the common fibular nerve passes.
  • Lateral malleolus: Stabilizes ankle joint and origin for lateral ligament of the ankle.
  • No function in weight bearing: Primarily an attachment site for muscles.

Leg Compartments

• Anterior Compartment: Includes tibialis anterior and extensor digitorum longus muscles.
• Posterior Compartment: Includes gastrocnemius, soleus, and plantaris muscles.
• Lateral Compartment: Contains fibularis longus and brevis muscles.

Retinacula

• Thickening of deep fascia around the ankle for retinacula.
• Includes superior and inferior extensor retinacula and superior and inferior peroneal retinacula.

Blood Supply

• Posterior tibial artery supplies the posterior compartment of the leg.
• Fibular artery also contributes to leg blood supply.

Nerve Supply

• Tibial nerve supplies posterior compartment.

Clinical Relevance

• Tibial Fracture: Often occurs at the mid-distal portion and has a slow healing time due to poor blood supply.
• Fibular Fracture: Occurs near the lateral malleolus, frequently with ankle dislocations or fractures.
• Bone Grafts: The fibula is often used for bone grafting.

Additional Components

• Popliteal Fossa: Diamond-shaped depression behind the knee joint.
• Flexor Retinaculum: Prevents tendons from bowstringing during movements.
• Peroneal Retinacula: Thickening of deep fascia at the distal fibula.
• Popliteal Aneurysm: Dilation of the popliteal artery exceeding 50% of normal size. This may compress a nerve and cause foot problems.

Common Conditions

• Tennis Leg: Caused by overstretching of gastrocnemius muscle, resulting in calf pain.
• Achilles Tendonitis: Repetitive strain injury of the Achilles tendon.
• Paralysis of Extensor Hallucis Longus: Results in persistent big toe flexion due to unopposed flexor muscle action.

This quiz focuses on the gross anatomy of the leg, covering the osteology, the muscles of its compartments, and their blood and nerve supply. It includes information about the tibia and fibula, their features, and functions within the lower limb. Test your knowledge on the anatomical structures and relationships in this crucial area of the body.