Lower Leg 1

Anatomy of the Tibia and Fibula

  • Tibia: The larger, medial weight-bearing "shin bone." It articulates proximally with the femur and fibula, and distally with the fibula and talus. Key landmarks include the tibial tuberosity, anterior crest, and medial malleolus.

  • Fibula: A smaller, lateral bone that is non-weight-bearing. It functions primarily to stabilize the ankle. Key landmarks include the head, lateral malleolus, and styloid process.

  • Interosseous membrane: A connective tissue membrane that joins the tibia and fibula along their shafts.

Structure of the Foot

  • Tarsal Bones (77): The ankle and proximal foot consist of the Talus, Calcaneus (heel bone), Navicular, Cuboid, and three Cuneiforms (medial, intermediate, and lateral).

  • Metatarsals (55): Mid-portion bones numbered 11 to 55. The first metatarsal is thicker to support increased weight-bearing.

  • Phalanges (1414): Toes 22 through 55 contain proximal, intermediate, and distal phalanges; the big toe contains only proximal and distal phalanges.

  • Sesamoid Bones: Bones developed within tendons, found on the posterior surface of the foot.

Primary Knee Ligaments

  • Anterior Cruciate Ligament (ACL): Prevents hyperextension and anterior sliding of the tibia relative to the femur.

  • Posterior Cruciate Ligament (PCL): Prevents posterior sliding of the tibia; essential for walking down inclines or stairs.

  • Medial Collateral Ligament (MCL): Also known as the tibial collateral ligament; stabilized by the tendons of the sartorius, gracilis, and semitendinosus muscles.

  • Lateral Collateral Ligament (LCL): Also known as the fibula collateral ligament; runs from the lateral femoral condyle to the fibular head and is covered by the biceps femoris tendon.

  • Patellar Ligament: A continuation of the quadriceps tendon that anchors the patella to the tibial tuberosity.

Stabilizing Ankle Ligaments

  • Deltoid Ligament: A group of 44 ligaments on the medial side that stabilizes the joint during eversion.

  • Anterior and Posterior Talofibular Ligaments: Located on the lateral side to resist inversion.

  • Calcaneofibular Ligament: Connects the calcaneus to the fibula; stabilizes the talofibular joint during dorsiflexion.