What is the bone below knee?

Below the knee are two long bones, the shin bone (tibia) and the fibula.

The tibia runs down the inside of the leg from the knee to the ankle. It bears most of the weight of the body when standing or walking.

The fibula is a thinner, less weight-bearing bone that lies beside the tibia. It helps to stabilize the leg and provides attachment points for muscles that move the leg and foot.