Structure and Function of the Fibula in Human Leg Anatomy
This article contains the anatomy of the fibula. Tibia and fibula bone constitutes the part of the leg. Fibula bone is slender and cylindrical in shape and is located on the limb's posterior portion. Both fibula and tibia bones lie next to each other. Tibia and fibula anatomy are essential to be well understood by all the students of biology.
Like the other long bones, the fibula has a proximal end consisting of the head and neck, a shaft, and a distal end. Tibia fibula bone runs parallel to one another in the leg and is of similar length. However, fibula bone is a bit thinner than the tibia. Thus, the thicker tibia has a more significant function for weight-bearing than the thinner fibula parts.
What is a Fibula?
The fibula is located in the lateral aspect of the leg, and its primary function is acting as the attachment for muscles and does not have a significant role in weight-bearing. This bone has three main articulations, which are as follows:
Proximal Tibiofibular Joint: This portion articulates with the tibia's lateral condyle.
Distal Tibiofibular Joint: This portion articulates with the tibia's fibular notch.
Ankle Joint: This portion articulates with the foot's talus bone.
[Image will be Uploaded Soon]
Fibula Anatomy: Bony Landmarks
Proximal: At the fibula's proximal end, it has an enlarged head containing a facet for articulation with the tibia's lateral condyle. However, the fibular neck's lateral and posterior surface, the common fibular nerve, cannot be found.
Shaft: There are three surfaces in the fibular shaft: anterior, lateral and posterior. The leg is divided into three compartments, and each of the surfaces faces the respective compartment, like, anterior surface faces the leg's anterior compartment.
Distal: At the distal end, the lateral surface moves inferiorly and is known as the lateral malleolus. It is more prominent than the medial malleolus and can be palpated at the leg's lateral side's ankle.
Joints Related to the Fibula Bone
Tibia and fibula bone articulates through 3 joints: the inferior, middle, and superior tibiofibular joints. A superior tibiofibular joint is a plane synovial joint that only allows the gliding movement with the transverse joint line spanning the medial fibular head and the tibia condyle. The capsule is anteriorly and posteriorly thicker, and it joins with the fibular head's anterior ligament that closely relates to the biceps femoris's tendon.
Tibia fibula bone also articulates through the interosseous membrane, also known as the middle tibiofibular ligament. It is composed of an aponeurotic lamina that is thinner and composed of oblique fibers. This ligament contains the lateral and medial attachments to fibular and tibial intraosseous margins, respectively. The membrane separates the muscle towards the leg's back from the muscle situated at the leg's front.
The inferior tibiofibular joint is a syndesmosis joint that has a fibrous structure and is slightly movable. It lies just above the ankle region, lying between the fibula's medial distal end and the lateral tibia's concave fibular notch region. This joint does not have any fibrous capsule surrounding it, but it has the anterior tibiofibular ligament that laterally descends between the leg's two bones.
Innervation and Blood Supply
There is a branch of the fibular artery that brings oxygenated blood for supplying to the bone. It travels through the fibula's nutrient foramen on a posterior surface, facilitating the passage of the fibular artery's branch into the bone. The foramen is some centimeters proximal to the shaft's midpoint.
The nerves supplying the ankle joints and the knee (the genicular branch of the common fibular nerve) also innervates the fibula's distal and proximal ends, respectively. Similarly, the deep and superficial fibular nerves innervating the fibula's muscles also innervate the fibular periosteum.
Fibula's Fractures
The lateral malleolus of the fibula, at the ankle, is prone to fractures. This might occur in the two main ways, which are as follows:
By forced external rotation of the ankle. This force of the talus against the bone leads to a spiral fracture of the lateral malleolus.
By foot getting twisted outwards, known as eversion. This is less common. Here, the talus gets pressed against the lateral malleolus and causes a transverse fracture.
FAQs on Fibula Bone Anatomy and Role in the Lower Leg
1. What is the fibula?
The fibula is the slender, lateral bone of the lower leg that runs parallel to the tibia. It is located on the outer side of the leg and is part of the appendicular skeleton. Unlike the tibia, it bears very little body weight but plays an essential role in ankle stability and muscle attachment.
- Position: Lateral (outer) side of the leg
- Type: Long bone
- Articulates with: Tibia and talus
2. Where is the fibula located in the body?
The fibula is located in the lower limb on the outer side of the leg between the knee and ankle. It lies parallel to the tibia and forms part of both the knee and ankle joints. Specifically:
- Upper end articulates with the tibia at the proximal tibiofibular joint
- Lower end forms the lateral malleolus of the ankle
3. What is the function of the fibula?
The primary function of the fibula is to provide ankle stability and serve as an attachment site for leg muscles. Although it supports minimal weight, it plays key roles in movement and joint stability.
- Stabilizes the ankle joint
- Forms the lateral malleolus
- Provides attachment for muscles like fibularis (peroneal) muscles
- Supports ligament attachment
4. Does the fibula bear weight?
The fibula bears very little body weight compared to the tibia. Most weight from the femur passes through the tibia to the foot, while the fibula mainly assists in stability and muscle attachment.
- Tibia: Major weight-bearing bone
- Fibula: Minor supportive role
- Important for balance and lateral support
5. What is the difference between the tibia and fibula?
The main difference between the tibia and fibula is that the tibia is a thick, weight-bearing bone while the fibula is slender and mainly provides stability. Key differences include:
- Tibia: Medial position, larger, bears weight
- Fibula: Lateral position, thinner, stabilizes ankle
- Tibia forms major part of knee joint; fibula does not directly articulate with the femur
6. What is the lateral malleolus?
The lateral malleolus is the distal (lower) end of the fibula that forms the outer part of the ankle. It helps stabilize the ankle joint by articulating with the talus bone.
- Located at the outer ankle
- Prevents excessive inversion
- Common site of ankle fractures
7. What muscles attach to the fibula?
Several leg muscles attach to the fibula, especially those involved in foot movement and ankle stability. Important muscle attachments include:
- Fibularis (peroneus) longus and brevis – foot eversion
- Soleus – plantar flexion
- Extensor hallucis longus – toe extension
- Tibialis posterior – foot support
8. Can you walk without a fibula?
Yes, a person can walk without a fibula because it is not the primary weight-bearing bone of the leg. In some medical procedures, part of the fibula can be removed without severely affecting walking.
- The tibia carries most body weight
- Ankle stability may be reduced if fully removed
- Rehabilitation strengthens surrounding muscles
9. What type of bone is the fibula?
The fibula is classified as a long bone because it has a shaft (diaphysis) and two ends (epiphyses). Like other long bones, it contains:
- A central medullary cavity
- Compact bone forming the outer layer
- Spongy bone at the ends
10. What happens if the fibula is fractured?
A fibula fracture is a break in the fibula that commonly occurs due to ankle twisting or trauma. Symptoms and outcomes include:
- Pain and swelling along the outer leg
- Difficulty bearing weight
- Possible damage to the lateral malleolus
