[Biology Class Notes] on Fibula Pdf for EXAM

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:

1. Proximal Tibiofibular Joint: This portion articulates with the tibia’s lateral condyle.

2. Distal Tibiofibular Joint: This portion articulates with the tibia’s fibular notch.

3. Ankle Joint: This portion articulates with the foot’s talus bone.

Fibula Anatomy: Bony Landmarks 

1. 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.

2. 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.

3. 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:

1. By forced external rotation of the ankle. This force of the talus against the bone leads to a spiral fracture of the lateral malleolus.

2. 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.