Pelvis & lower limb · Leg
Fibula
The fibula is the slender bone on the lateral side of the leg. Its head articulates with the lateral condyle of the tibia below the knee, and its lower end forms the lateral malleolus, the outer wall of the ankle joint.
- Latin (TA)
- Fibula
- Type
- Long bone: a slender shaft with two ends
- Side
- Paired — right and left
- Model size
- 36.2 cm longest
Showing a right bone. Rotate it to inspect every surface; switch sides to practise siding.
3D model: Z-Anatomy (CC BY-SA 4.0), derived from BodyParts3D © DBCLS (CC BY-SA 2.1 JP). Adapted by PharmaWallah. Credits & licence
Landmarks
15 of 15 marked on the modelTap a landmark to find it on the bone and read what it is.
The expanded upper end of the fibula.
Where: At the top, just below and behind the lateral condyle of the tibia; palpable on the outer side of the knee.
Why it matters: Gives attachment to biceps femoris and the fibular collateral ligament; it is the upper end, used for orientation.
Related: Biceps femoris, fibular collateral ligament, fibularis longus, soleus.
Marked on the model at the point Z-Anatomy places this label.
A small round articular facet on the upper medial part of the head.
Where: On the head, facing upwards and medially.
Why it matters: Articulates with the fibular facet of the lateral tibial condyle at the superior tibiofibular joint.
Marked on the model at the point Z-Anatomy places this label.
The narrow part just below the head.
Where: Immediately below the head, on the lateral side of the upper leg.
Why it matters: The common fibular nerve winds round the lateral side of the neck, where it lies on bone just under the skin and is easily injured.
Viva: Which nerve is related to the neck of the fibula, and what happens if it is injured?
Marked on the model at the point Z-Anatomy places this label.
The long, slender middle part of the fibula, often twisted.
Where: Between the neck and the lateral malleolus.
Why it matters: Mainly a site for muscle attachment; little body weight passes through it.
Marked on the model at the point Z-Anatomy places this label.
A ridge on the medial side of the shaft facing the tibia.
Where: Along the medial side of the shaft, just behind the anterior border.
Why it matters: Attachment of the interosseous membrane.
Related: Interosseous membrane.
Marked on the model at the point Z-Anatomy places this label.
The surface between the anterior and posterior borders.
Where: On the outer side of the shaft; it twists to face backwards in its lower part.
Why it matters: Origin of fibularis longus (upper part) and fibularis brevis (lower part), the muscles of the lateral compartment.
Related: Fibularis longus, fibularis brevis.
Marked on the model at the point Z-Anatomy places this label.
A narrow surface between the anterior and interosseous borders.
Where: On the front-medial side of the shaft.
Why it matters: Origin of the extensor muscles of the anterior compartment: extensor digitorum longus, extensor hallucis longus and fibularis tertius.
Related: Extensor digitorum longus, extensor hallucis longus, fibularis tertius.
Marked on the model at the point Z-Anatomy places this label.
The broadest surface, between the interosseous and posterior borders.
Where: On the back of the shaft.
Why it matters: Origin of soleus (upper part), flexor hallucis longus (lower part) and tibialis posterior.
Related: Soleus, flexor hallucis longus, tibialis posterior.
Marked on the model at the point Z-Anatomy places this label.
The expanded lower end of the fibula.
Where: At the lower end, forming the bony bump on the outer side of the ankle; it reaches lower and lies further back than the medial malleolus.
Why it matters: Forms the lateral wall of the ankle socket and anchors the lateral ligaments of the ankle.
Related: Ankle joint; anterior and posterior talofibular and calcaneofibular ligaments.
Viva: Which ligaments are attached to the lateral malleolus?
Marked on the model at the point Z-Anatomy places this label.
A smooth triangular facet on the medial side of the lateral malleolus.
Where: On the inner surface of the malleolus, apex pointing down.
Why it matters: Articulates with the lateral side of the talus at the ankle joint; it faces medially, which is used to side the bone.
Marked on the model at the point Z-Anatomy places this label.
A deep pit behind the articular facet of the lateral malleolus.
Where: On the medial side of the malleolus, behind and below the articular facet.
Why it matters: Attachment of the posterior talofibular ligament; it lies posteriorly, which is used to side the bone.
Related: Posterior talofibular ligament.
Marked on the model at the point Z-Anatomy places this label.
Classification & region
Long bone: a slender shaft with two ends. It is the thin lateral bone of the leg and bears little of the body weight.
- Proximal end (head)
- A knob-like head with a pointed apex and a round facet for the tibia, joined to the shaft by a short neck.
- Shaft (body)
- Long and slender, with anterior, interosseous and posterior borders and lateral, medial and posterior surfaces; it is mostly buried in muscle.
- Distal end (lateral malleolus)
- Flattened and projecting down as the lateral malleolus, with a triangular articular facet on its medial side and the malleolar fossa behind that facet.
Hold it in the anatomical position
- Put the rounded head at the top and the flattened lateral malleolus at the bottom.
- Turn the triangular articular facet of the malleolus to face medially (towards the tibia).
- The malleolar fossa, behind the facet, then faces backwards.
Right or left? Side determination
- Tell the ends apart: the lower end is flattened from side to side and carries a triangular articular facet; the upper end (head) is rounded with a small round facet.
- Put the lateral malleolus at the bottom.
- Turn the malleolar fossa (the deep pit just behind the articular facet) backwards, towards you, as if the bone were in your own leg.
- The triangular articular facet now faces medially, towards the midline; the bone belongs to the other side.
- Held this way, a facet facing your left means a right fibula.
A fibula is easier to side by its lower end than its upper end; the shaft is variable and twisted.
Check yourself: switch the 3D model to “Left bone” and apply the same steps.
Articulations
- With the tibia (lateral condyle) at the Superior (proximal) tibiofibular joint — Articular facet of the head.
- With the tibia (fibular notch) at the Inferior (distal) tibiofibular joint (syndesmosis) — Rough medial surface of the lower end, above the malleolar facet.
- With the talus at the Ankle (talocrural) joint — Articular facet of the lateral malleolus.
Muscle and ligament attachments
| Structure | Type | Where on the bone |
|---|---|---|
| Biceps femoris | insertion | Head of the fibula |
| Fibular (lateral) collateral ligament of the knee | ligament | Head of the fibula |
| Fibularis longus | origin | Head and upper part of the lateral surface |
| Fibularis brevis | origin | Lower part of the lateral surface |
| Extensor digitorum longus | origin | Upper part of the medial surface (and the lateral tibial condyle) |
| Extensor hallucis longus | origin | Middle part of the medial surface |
| Fibularis tertius | origin | Lower part of the medial surface |
| Soleus | origin | Back of the head and upper part of the posterior surface |
| Flexor hallucis longus | origin | Lower part of the posterior surface |
| Tibialis posterior | origin | Posterior surface, next to the interosseous border |
| Interosseous membrane | ligament | Interosseous border |
| Anterior talofibular ligament | ligament | Front of the lateral malleolus |
| Posterior talofibular ligament | ligament | Malleolar fossa |
| Calcaneofibular ligament | ligament | Tip of the lateral malleolus |
Functions
- Forms the lateral wall of the ankle socket, which keeps the talus stable.
- Gives attachment to many leg muscles and to the interosseous membrane.
- Bears little of the body weight; its main role is muscle attachment and ankle stability.
Clinical & practical relevance
- The common fibular nerve winds round the neck of the fibula; a fracture there, or pressure from a tight plaster cast, can injure it and cause foot drop.
- Fractures of the lateral malleolus are among the most common ankle fractures, usually from twisting injuries.
- The anterior talofibular ligament is the ligament most often injured in an inversion ('rolled ankle') sprain.
- Because the fibula carries little weight, a segment of its shaft can be removed and used as a bone graft.
Identification tips
- The fibula does not reach the knee joint: its head sits below the lateral tibial condyle.
- The lateral malleolus is lower and further back than the medial malleolus.
- Malleolar fossa behind, facet medial: think 'pit at the back, face to the talus'.
Common student mistakes
- Saying the fibula articulates with the femur: it takes no part in the knee joint.
- Holding the fibula upside down: the lower end is flattened with a triangular facet, the head is rounded.
- Confusing the malleolar fossa (posterior talofibular ligament) with the malleolar groove (fibularis tendons).
- Calling the fibula a major weight-bearing bone: the tibia carries the weight.
Common exam questions
How do you determine the side of a fibula?Show answer
Lateral malleolus down, malleolar fossa backwards; the triangular articular facet faces medially, towards the midline.
Which nerve is related to the neck of the fibula and what is the effect of injury?Show answer
The common fibular nerve; injury causes foot drop, with loss of dorsiflexion and eversion.
Name the muscles arising from the lateral surface of the fibula.Show answer
Fibularis longus (upper part) and fibularis brevis (lower part).
Name the ligaments attached to the lateral malleolus.Show answer
Anterior talofibular, posterior talofibular (in the malleolar fossa) and calcaneofibular.
Name the joints formed by the fibula.Show answer
Superior tibiofibular (synovial), inferior tibiofibular (syndesmosis) and the ankle joint with the talus.
Why can the fibula be used as a bone graft?Show answer
Because it carries little body weight, so a segment of its shaft can be removed.
What structure is attached to the head of the fibula?Show answer
The tendon of biceps femoris and the fibular collateral ligament of the knee.
Revision summary
- Slender lateral long bone of the leg; little weight-bearing.
- Head with apex and round facet above; neck below it; lateral malleolus at the lower end.
- Common fibular nerve winds round the neck: injury gives foot drop.
- Lateral malleolus: facet medial, fossa posterior, groove for fibularis tendons behind.
- Lateral ankle ligaments: anterior and posterior talofibular and calcaneofibular.
- Joints: superior and inferior tibiofibular, and the ankle.
Test yourself on the fibula
Spotting questions on bones, sides and landmarks — untimed, with explanations.
Joints of the fibula
References
- Drake RL, Vogl AW, Mitchell AWM. Gray's Anatomy for Students. 5th ed. Philadelphia: Elsevier; 2023.
- Moore KL, Dalley AF, Agur AMR. Moore's Clinically Oriented Anatomy. 9th ed. Philadelphia: Wolters Kluwer; 2023.
- Federative International Programme for Anatomical Terminology (FIPAT). Terminologia Anatomica. 2nd ed. FIPAT.library.dal.ca; 2019. fipat.library.dal.ca/TA2
- Kervyn G, Zielinski M, Vinent L, et al. Z-Anatomy: the libre 3D atlas of anatomy. Models derived from BodyParts3D, The Database Center for Life Science (CC BY-SA 2.1 JP). CC BY-SA 4.0. www.z-anatomy.com/
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