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Recommended video: Fibula [06:26]
Anatomy and function of the fibula.

In this article, we'll discuss the anatomy of the fibula. The fibula is a slender, cylindrical leg bone that is located on the posterior portion of the limb. It is found next to another long bone known as the tibia. A long bone is defined as one whose body is longer than it is wide.

Like other long bones, the fibula has a proximal end (with a head and neck), a shaft, and a distal end. The fibula and tibia run parallel to each other in the leg and are similar in length but the fibula is much thinner than the tibia. This is indicative of the weight-bearing contributions of each bone. In other words, the thicker tibia has a much greater function in weight-bearing than the fibula.

Key facts about the fibula
Proximal end Apex – styloid process
Head of the fibula – with facet to articulate with the lateral tibial condyle
Short neck – with common fibular nerve behind it
Body Three borders – anterior, interosseous, posterior
Three surfaces – medial, lateral, posterior
Distal end Lateral malleolus
Point of ligamentous attachment
Joints Superior tibiofibular joint – plane synovial joint
Middle tibiofibular joint – attached by the interosseous membrane
Inferior tibiofibular joint – syndesmosis 
Also participates in the ankle mortise joint
Blood supply Fibular artery
Innervation Proximal end – genicular branch of the common fibular nerve
Distal end - deep fibular nerve
Periosteum - superficial and deep fibular nerves
Clinical points Fractures are most commonly traumatic
Isolated fibular fractures are less common than combined tibial and fibular fractures
Proximal fibular fractures are associated with common fibular nerve injury
Distal fibular fractures may be described using the Weber (Danis-Weber) system
Mnemonic FibuLA is LAteral

There are several key facts about the fibula that most anatomy students should be familiar with. These and other important points about the anatomy, blood supply, innervation, and muscular and ligamentous attachments are addressed in this article. The article will also discuss important fractures of the fibula. 

  1. Development
  2. Proximal end
  3. Body
  4. Distal end
  5. Joints 
  6. Muscle attachments 
  7. Blood supply and innervation
  8. Clinical points
  9. Sources
+ Show all


Endochondral ossification (histological slide)

The fibula is a part of the appendicular skeleton and develops via endochondral ossification. There are three points at which ossification begins in the fibula:

  • the body around the 8th gestational week 
  • the distal end by the end of the first year of life
  • the proximal end at around four-years-old in males and three-years-old in females

The ossification centers of the body and distal end of the bone eventually fuse during the mid-adolescent years (at 15 years old for females and 17 years old for males). The bony centers of the proximal part and shaft of the fibula are the last to unite during the late adolescent years (around 17 years for females and 19 years for males).

Proximal end

The proximal end of the fibula is characterized by an irregularly shaped head and a short neck. It has three segments which project in different directions: anteriorly, posteriorly, and laterally. An important question that pops up on a lot of anatomy tests is with what bony structure does the head of the fibula articulate? There is a round, flattened area on the medial part of the fibular head known as a facet. It articulates with a complementary facet on the inferolateral part of the lateral tibial condyle (proximal tibiofibular joint). The facet also acts as a point of attachment for the tibiofibular capsular ligament. Additionally, the tibiofibular capsular ligament surrounds the articular facet of the fibula. 

There is a styloid process of the fibula that extends superiorly from the head; it is more commonly referred to as the apex of the head of the fibula. This apical projection protrudes from the posterolateral part of the fibular head. The neck of the fibula is a short bare region just below the fibular head. What important structures pass around the neck of the fibula? Importantly, the common fibular nerve (also called the common peroneal nerve) travels posterolaterally to the fibular neck. This has clinical significance as trauma to the neck of the fibula can present with neurological deficits.

The function of the proximal end of the fibula is to provide points of attachment for minor supporting ligaments of the knee joint. There is the fibular collateral ligament that arises from the fibular apex and is surrounded by the tendon of biceps femoris.


The majority of the fibula is made up by its body (or shaft). This part of the bone is triangular in cross-section and consequently has three borders (anterior, interosseous, and posterior) and three surfaces (lateral, medial, and posterior) found along the shaft of the fibula. The borders are the sharp longitudinal edges that run along the bone’s long axis. On the other hand, the surfaces are the flattened areas that exist between the borders. 

The anterior border starts at the fibular head and continues distally toward the lateral malleolus, where it diverges into two ridges that surround the triangular subcutaneous surface. On the medial aspect of the fibula is the interosseous or medial border. It is the point of attachment of the fibrous interosseous membrane of the leg that forms the middle tibiofibular joint. This fibrous septum acts as a barrier between the extensor and fibular muscles. There is a posterior border that runs along the back part of the fibula. The proximal part of the border appears slightly rounded. However, the border becomes more prominent distally, as it approaches the medial segment of the lateral malleolus.

The interosseous and anterior borders of the fibula act as medial and lateral boundaries of the medial surface. This surface provides a point of attachment for the muscles that extend the foot and cause the toes to point upward (dorsiflexion). 

The lateral surface is found on the opposite side of the medial surface, between the posterior and anterior borders. The proximal part of the surface faces laterally; however, the surface spirals toward the distal end and as such part of the surface faces posterolaterally. By virtue of this shift, the distal part of the lateral surface is in continuity with the posterior groove of the lateral malleolus. The lateral surface provides a point of attachment for the fibular (peroneal) muscles

The posterior surface is found between the posterior and interosseous borders. The surface is much more narrow at the proximal part (where the interosseous and posterior borders are closest) than it is distally (where the borders are farthest apart). This surface provides attachment for the flexor muscles of the foot which are responsible for pointing the toes downward (plantar flexion).

Distal end

The distal end of the fibula forms the lateral malleolus of the lower limb. This is a bony projection noted on the lateral surface of the ankle, which is complementary to another bony projection on the medial aspect of the ankle called the medial malleolus (formed by the tibia). The lateral malleolus extends posteroinferiorly, is round and rough anteriorly, and has a broad groove posteriorly. The lateral surface is covered by skin (so there is no muscular layer at this area) and the medial surface has a triangular area that is convex along the vertical axis. The distal end of the fibula tapers off as an apical projection that articulates with the lateral aspect of the talus.

The distal end provides attachment for several ligaments that support the ankle joint. The posterior tibiofibular, posterior talofibular, calcaneofibular, and interosseous (middle) tibiofibular ligaments all have attachments to the end of the fibula and participate in the stability of this joint.

Test yourself on the structures of the tibia and fibula with this interactive quiz.


The tibia and fibula articulate through three joints–the superior, middle, and inferior tibiofibular joints. The superior tibiofibular joint is a plane synovial joint (allows only gliding movement) with the transverse joint line spanning the lateral tibial condyle and the medial fibular head. The capsule is thickened anteriorly and posteriorly and joins with the anterior ligament of the fibular head, relating closely to the tendon of biceps femoris. 

The tibia and fibula also articulate via an interosseous membrane that is also called the middle tibiofibular ligament. It is made of an aponeurotic lamina which is thin and made of oblique fibers. This ligament has medial and lateral attachments to the tibial and fibular interosseous margins respectively. The membrane separates the muscles in the back of the leg from the muscles located in the front of the leg. 

The inferior tibiofibular joint is a syndesmosis joint (slightly movable, fibrous joint), just above the ankle region which lies between the medial distal end of the fibula and the concave fibular notch region of the lateral tibia. There is no fibrous capsule surrounding this joint but there is the anterior tibiofibular ligament which descends laterally between the two leg bones.

More information about the fibula, tibia, knee and ankle joint is provided below:

Muscle attachments 

What is the function of the fibula? The bone provides a point of origin for a number of muscles of the foot. However, only one muscle inserts on this long bone. So what structures are attached to the fibula? The table below summarizes the muscles that originate from, and insert on the fibula. Note that the muscles are listed from cranial to caudal, and those attached to the anterior surface are listed before those on the posterior surface.

Muscles attached to the anterior surface of the fibula
Biceps femoris Inserts on the head of the fibula
Extensor digitorum longus Proximal half of medial surface of fibula (and lateral tibial condyle)
Fibularis longus Head of fibula, Superior two-thirds of lateral surface of fibula,
Intermuscular septa
Extensor hallucis longus Medial surface of fibula, Interosseous membrane
Fibularis brevis Inferior third of lateral surface of fibula
Fibularis tertius Distal anteromedial surface of fibula
Muscles attached to the posterior surface of the fibula
Soleus Head of fibula, Posterior border of fibula (and the medial border and soleal line of the tibia)
Tibialis posterior Posterior surface of fibula, Interosseous membrane (and posterior surface of tibia)
Flexor hallucis longus Posterior surface of fibula, Interosseous membrane

Blood supply and innervation

A branch of the fibular artery brings oxygen-rich blood to supply the bone. It travels through a nutrient foramen on the posterior surface of the fibula that facilitates passage of a branch of the fibular artery into the bone. The foramen is a few centimeters proximal to the midpoint of the shaft. 

The nerves that supply the knee (genicular branch of the common fibular nerve) and ankle (deep fibular nerve) joints also innervate the proximal and distal ends of the fibula, respectively. Similarly, superficial and deep fibular nerves, which innervate the muscles attached to the fibula, also innervate the fibular periosteum

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