Tibia
The shin bone (lat. Tibia) represents one of the two lower leg bones. In contrast to the fibula, it has a connection to the thigh bone and is considerably stronger.
Anatomy
The shin bone is one of the two tubular bones of the lower leg bones. It is located on the medial side of the leg. The fibula is laterally adjacent. It is the second longest bone after the femur and can be divided into three parts: the corpus tibiae (tibia shaft), the extremity proximalis (tibia head) and the extremity malleolaris.
Tibia shaft
The tibia shaft represents the longest part of the bone. It has a triangular cross-section and thus has three edges and also three surfaces. The most pronounced anterior edge is called Margo anterior. It begins at the proximal end of the head of the tibia and flattens significantly in the direction of the extremity malleolaris. This edge separates the outer surface (facies lateralis) from the inner surface (facies medialis). Between the back (Facies posterior) and the outer surface is the margo interosseus. The last edge is the inner edge (margo medialis). This represents the transition from the inner surface to the back. At the top of the back surface a slightly rough line can be seen, the Linea musculi solei.
Tibia head
The head of the tibia (proximal extremities or caput tibiae) is the proximal epiphysis. It is widened, thus creating the clearly visible tibial head with its massive bone structure. It is made up of two large bone parts, the medial condyle and the lateral condyle. Together these two parts form the tibial plateau. There the tibia articulates with the femur via the articular surface (Facies articularis superior). The articular surface has a bony hill (Eminentia intercondylaris) in the middle, which divides the articular surface into two parts. The distal transition from the head of the tibia to the tibia shaft is characterized by a rough elevation, the tibial tuberosity.
Extremitas malleolaris
The extremity malleolaris is the distal end of the tibia. On its medial side there is a bony extension. This represents the inner ankle (malleolus medialis). The distal end of the tibia is generally narrower than the head of the tibia. It articulates with the talus via a concave joint surface, the facies articularis malleoli medialis. The sulcus malleolaris represents an elongated depression at the back of the malleolus madialis. The incisura fibularis provides the connection to the fibula.
Function
The main function of the shinbone is to connect the thigh or knee to the foot. Furthermore, the shin bone has a major function as a supporting pillar of the leg. It carries most of the human weight and thus contributes to the human stance and gait.
Development
The tibia shaft begins to ossify in the seventh week of embryonic development. The ossifications of the proximal and distal ends do not occur until much later, between the 10th fetal month and the first year of life. Complete closure of the epiphyses does not occur until between the seventeenth and twentieth year of life.
