Fibula
The fibula is the narrower of the two lower leg bones. It runs approximately parallel to the tibia and is located on the lateral side of the lower leg.
Anatomy
The fibula is a relatively elastic tubular bone of the lower leg. It lies laterally next to the shinbone and is clearly narrower than it. It can be divided into three sections: the fibula shaft, the fibula head and the lateral malleolus.
Fibula shaft
The fibula shaft has a triangular cross section and therefore has three sides. However, there are up to four edges on the Corpus fibulae. The outer surface (Facies lateralis) is separated from the inner surface (Facies medialis) by the strongly pronounced anterior Margo, which points forward. The Margo interosseus represents the border between the inner surface and the posterior surface (Facies posterior). On the other hand, the posterior margin separates the back surface from the outer surface. In the lower part of the back surface there is usually a fourth edge, this is called the crista medialis.
Fibula head
The proximal end of the fibula is characterized by a sphere-like bone structure, this is the head of the fibula (Caput fibulae). On its inner side there is a joint surface, the Facies articularis capitis fibulae. Via this the fibula makes the connection to the tibia. On the cranial side of the head of the fibula there is a small bony protrusion. This is called the apex capitis fibulae.
Malleolus lateralis
The distal end of the fibula is the Malleolus lateralis. This is the external ankle and is indicated by a prolonged bony protrusion. This extends a little further distally than the inner ankle on the other side. The malleolus fork is formed by the two ankles. On the rear side of the Malleolus alteralis there is a dent, the Sulcus malleolaris lateralis. The inside of the distal fibula is marked by the articular surface Facies articularis malleoli lateralis.
Function
In contrast to the shinbone, the fibula does not have a major supporting function. It is mainly used as a point of attachment and origin for muscles and tendons. However, the fibula is involved in the ankle joint and transmits forces to the foot via the outer ankle. The fibula also serves as a further anchor point for the shinbone and stabilises it.
Evolution
The ossification of the fibula shaft begins in the second embryonic month. Complete ossification of the ends of the fibula does not occur until the second year of life. The closure of the epiphyseal fugues takes place between the ages of 16 and 20.
