The human shinbone, also called the tibia, resides in the lower leg. Humans have two tibias as well as two fibulas, which are the second of two long bones that connect the knee to the ankle. The tibia is larger than the fibula and is found on the interior part of the lower leg, while the fibula is located on the outside.
The tibia is one of the longest bones in the body and is relatively strong. Like the fibula, the tibia contains several layers of bone, including a soft core and hard outer-layer. Although the tibia and fibula have similar roles in supporting human movements such as walking and running, the tibia bears the primary responsibility for supporting weight. The tibia and fibula bones are connected to each other through a series of membranes and muscles. A special joint, called the syndemosis, connects the tibia and fibula bones. This joint contains fluid to prevent the bones from rubbing each other and it restricts movement. The tibia is one of the strongest weight-bearing bones in the body, and it is the second largest bone, ranking just behind the femur in size. As with other long bones, tibia bones contain two distinct sections: the diaphysis and epiphyses. The diaphysis forms the midsection, or shaft, of the tibia, while the epiphyses forms the ends.