shinbone

The tibia, commonly known as the shinbone, is the larger, medial bone of the lower leg. It bears most of the body's weight in standing and locomotion and, with the fibula, forms the skeleton of the lower leg.

The proximal end features two tibial condyles that articulate with the femoral condyles to form the knee joint; between them lies the intercondylar eminence. Anteriorly, the tibial tuberosity serves as the attachment for the patellar ligament. The shaft has the anterior crest, a subcutaneous ridge that can be felt along the shin.

The distal end expands to form the medial malleolus, the bony bump on the inner ankle, which articulates with the talus at the ankle joint and, with the fibula, contributes to the ankle mortise. The tibia articulates with the fibula at the proximal and distal tibiofibular joints. The interosseous membrane links the tibia and fibula along their lengths.

Function and relations: The tibia transmits weight from the femur to the foot and provides attachment sites for many muscles, including the quadriceps via the patellar tendon, and the calf muscles on its posterior surface. The cortex provides weight-bearing strength, while the inner medullary cavity contains bone marrow.

Clinical notes: The tibia is relatively prone to fractures, particularly from direct trauma or high-energy injuries; shin splints refer to tibial stress injuries. Healing can be slow due to variable blood supply, especially at the ends; treatment ranges from immobilization to surgical fixation with rods or plates. Complications can include malunion, nonunion, and compartment syndrome.