Leg Anatomy

Learning Outcomes for Leg Anatomy

• Detailed description of the anatomy of the tibia and fibula, including their specific articulations.

• Integration of lower leg anatomy with the understanding of the ankle joint.

• Introduction to the anatomy and function of the knee joint.

Anatomy of the Fibula

• Position and General Characteristics:

  • The fibula is classified as a long bone located in the lateral aspect of the leg.

  • Its primary functional role is to stabilize the ankle joint.

  • The fibula plays no part in the articulation of the knee joint.

  • It is a non-weight-bearing bone.

• Structural Components of the Head:

  • The head of the fibula is the expanded proximal end of the bone.

  • It is thicker than the distal end.

  • Features an apex (a pointed projection).

  • Articulates specifically with the lateral condyle of the tibia.

  • The head is followed by a constricted region known as the neck.

• The Fibular Shaft:

  • Characterized as long and slender.

  • Physically possesses $4$ borders and $4$ surfaces.

  • Includes an interosseous border, which serves as the attachment point for the interosseous membrane.

• Distal Features of the Fibula:

  • The distal end features the lateral malleolus, which is triangular in shape.

  • The medial surface of the lateral malleolus articulates with the lateral aspect of the talus.

  • The malleolar fossa is a specific depression located on the posterior medial aspect of the distal fibula.

• Summary of Fibula Articulations:

  • Proximal: The head of the fibula articulates with the articular facet on the lateral tibia.

  • Middle/Distal: Use of the fibular notch for articulation with the tibia.

  • Distal: The lateral malleolus articulates with the talus bone of the foot.

Anatomy of the Tibia

• Position and General Characteristics:

  • The tibia is the large, weight-bearing bone located on the medial side of the leg.

• Primary Articulations of the Tibia:

  • Superior/Proximal: Articulates with the condyles of the femur.

  • Lateral Proximal: Articulates with the head of the fibula at the lateral tibial condyle.

  • Inferior/Distal: Articulates with the body (dome) of the talus.

  • Lateral Distal: Articulates with the fibula at the fibular notch.

• Proximal Main Features:

  • Medial and Lateral Tibial Condyles: Also referred to as the tibial plateaus.

  • Intercondylar Eminence: An elevation located between the medial and lateral condyles.

  • Articular Facet: Located on the lateral condyle for articulation with the head of the fibula.

• The Tibial Shaft:

  • The shaft is triangular in cross-section.

  • Anterior Border (Anterior Crest): A prominent ridge that is easily palpable and forms the shin.

  • Tibial Tuberosity: An anterior projection located proximally; it serves as the site for the attachment of the patellar tendon.

  • Interosseous Border: Serves as the attachment site for the interosseous membrane connecting to the fibula.

  • Soleal Line: A bony ridge located on the upper posterior aspect of the shaft; it acts as the attachment point for the soleus muscle.

• Distal Main Features:

  • Medial Malleolus: A large, prominent, and palpable bony projection on the medial side of the ankle.

  • Inferior Articular Surface (Plafond): A saddle-shaped surface on the inferior border for articulation with the dome of the talus.

  • Fibular Notch: A depression located on the lateral aspect of the distal tibia for articulation with the fibula.

Anatomy and Features of the Patella

• Position and Classification:

  • The patella is the largest sesamoid bone in the human body.

  • It is located within the tendon of the quadriceps femoris muscle, situated anterior to the femur.

  • The bone is triangular in shape.

• Main Structural Features:

  • Base: The superior part of the bone, associated with the quadriceps femoris.

  • Apex: The inferior part of the bone; it is the attachment point for the ligamentum patellae.

  • Posterior Surface: This surface articulates with the femur. It is divided into two articular facets:

    • Medial Surface: The smaller of the two facets.

    • Lateral Surface: The larger of the two facets.

• Articulation:

  • The medial and lateral facets of the posterior patella articulate with the patellar surface located on the anterior aspect of the femur.

Leg Bone Landmarks and Connectivity

• Interosseous Membrane: A connective tissue sheet that spans the gap between the interosseous borders of the tibia and fibula, linking the two bones along their shafts.

• Proximal Tibiofibular Joint: The articulation point between the head of the fibula and the lateral condyle of the tibia.

• Distal Tibiofibular Joint: The articulation point between the fibular notch of the tibia and the distal fibula.

• Anterior vs. Posterior Views of the Tibia:

  • Anterior View: Shows the tibial tuberosity, anterior crest, medial malleolus, and intercondylar eminence.

  • Posterior View: Highlights the soleal line, the posterior aspect of the condyles, and the fibular notch.