Fibula is a slender long bone, a bone with a shaft and expanded ends, on the outer side of the leg between the knee and ankle. It lies beside the larger tibia, or shin bone, and forms the outer ankle prominence. Its main roles are muscle attachment and ankle stability rather than carrying most body weight.
Where is the fibula located?
The fibula lies lateral to the tibia: lateral means farther from the body's midline. In anatomical terminology, the leg is the region between the knee and ankle, rather than the entire lower limb. The fibula extends from just below the knee to the outer side of the ankle.
The left fibula and right fibula occupy corresponding positions on either side of the body. Their upper ends sit slightly behind the outer part of the tibia, while their lower ends extend farther down than the tibia's inner ankle prominence.
A strong sheet of connective tissue called the interosseous membrane spans the space between the shafts of the tibia and fibula. It helps bind the bones together, provides muscle attachment, and separates muscle groups at the front and back of the leg.
What are the main parts of the fibula?
The proximal end, meaning the end nearer the trunk, consists of the head and neck. The head is the expanded upper end and has an articular surface, a smooth surface that meets another bone at a joint. A pointed projection rises from the head, and the narrower neck lies immediately below it.
The shaft is the elongated middle portion. Its anterior, posterior and interosseous borders separate lateral, medial and posterior surfaces; anterior means towards the front, posterior towards the back, and medial towards the body's midline. The interosseous border faces the tibia and anchors the interosseous membrane.
The distal end, meaning the end farther from the trunk, expands into the lateral malleolus, the bony prominence on the outer ankle. Its inner surface meets the talus, the ankle bone beneath the tibia. Behind this joint surface lies the malleolar fossa, a depression that receives a ligament attachment.
| Part or landmark | Location | Main anatomical relationship |
|---|---|---|
| Head | Upper end | Joins the tibia and receives tendon and ligament attachments |
| Neck | Immediately below the head | Closely related to the common fibular nerve |
| Shaft | Between the expanded ends | Provides broad muscle attachment surfaces |
| Interosseous border | Border facing the tibia | Anchors the interosseous membrane |
| Lateral malleolus | Lower end | Meets the talus and forms the outer ankle prominence |
Which joints does the fibula form?
The proximal tibiofibular joint connects the fibular head to the outer part of the upper tibia. It is a synovial joint, meaning its opposing surfaces are covered with cartilage and enclosed within a capsule containing joint fluid. Small gliding movements occur here.
At the lower end, the distal tibiofibular joint joins the fibula to the tibia through strong ligaments. This is a syndesmosis, a joint in which bones are bound together by fibrous connective tissue. It maintains the relationship between the bones while allowing slight movement during ankle motion.
The lateral malleolus also contributes to the ankle joint by meeting the talus. Together, the lower tibia and fibula form a socket around the talus. The fibula does not meet the femur, or thigh bone, and is not an articulating surface of the knee joint.
Which muscles and ligaments attach to the fibula?
The fibula provides attachment sites for muscles of the muscular system that move the foot and toes. A muscle's origin is its attachment that usually remains relatively fixed during an action; its insertion is the attachment that usually moves. A tendon is the connective tissue that joins a muscle to its attachment site.
Important attachments include:
- The biceps femoris tendon inserts onto the fibular head.
- The soleus originates partly from the head and upper posterior fibula.
- The fibularis longus and fibularis brevis originate from the lateral surface.
- The extensor digitorum longus and extensor hallucis longus have origins on the fibula.
- The flexor hallucis longus originates from the posterior surface.
Ligaments are strong bands of connective tissue that connect bones. The fibular collateral ligament of the knee attaches to the head. At the lateral malleolus, ligaments connect the fibula to the talus and calcaneus, or heel bone, helping support the outer ankle.
What does the fibula do?
Within the skeletal system, the fibula provides a firm framework for muscle attachment and helps stabilise the ankle. The tibia carries most of the weight transmitted through the leg, although the fibula participates in load transmission.
The lateral malleolus forms the outer wall of the ankle socket and helps restrain sideways displacement of the talus. The fibula's connections with the tibia also maintain the arrangement of the leg bones during movement.
What lies close to the fibular head and neck?
The common fibular nerve passes behind the fibular head and winds around the neck. It then divides into superficial and deep fibular nerves, which supply muscles and skin in parts of the leg and foot. Its close relationship to the neck is an important anatomical landmark.
The head lies near the biceps femoris tendon and the fibular collateral ligament. These relationships help distinguish the upper fibula from the broader upper tibia beside it.
How can you find the fibula in the 3D model?
In the 3D model next to this article, select the fibula and isolate it. Rotate the view and zoom in or out, then adjust the view again from a different angle. You can also hide or fade selected parts and switch layers to change the view.
For other ways to explore the model, cut a section along the sagittal, coronal or transverse plane, or pull parts apart. Combine these controls with rotation, zooming and selection to try different views without assuming that every anatomical detail is modelled.