The lower leg is a major anatomical part of the skeletal system. Together with the upper leg, it forms the lower extremity. It lies between the knee and the ankle, while the upper leg lies between the hip and the knee.

The lower leg contains two major long bones, the tibia and the fibula, which are both very strong skeletal structures. The tibia (also called the shinbone) is located near the midline of the leg and is the thicker and stronger of the two bones. The fibula, also called the calf bone, is significantly smaller and is situated on the lateral (farther from the midline) side of the tibia.

The main muscle in this area of the leg is the gastrocnemius, which gives the calf a bulging muscular appearance. Some nerves of the sacral plexus innervate this area, namely the superficial fibular nerve, the deep fibular nerve and the tibial nerve.

The anterior tibial, posterior tibial, and the fibular arteries supply blood to the lower leg. These blood vessels supply oxygen and nutrients to the surrounding structures—bones, muscles and nerves.

The lower leg constitutes a major portion of a person's overall mass. It also functions primarily for standing, walking, running, jumping, and other similar weight-bearing activities; as a result, most fractures occur in this area.