Bones

Fibula Bone : Structure, Attachments, Functions & Clinical Anatomy

Fibula Bone (Calf Bone) : Anatomy, Parts, Location, Side Determination, Anatomical Position, Attachments, Functions, Fracture, Pain, & Pictures

Overview

  • Fibula bone is the lateral & smaller bone of the leg.
  • It is very thin as compared to the tibia.
  • It is considered as homologous with the ulna of the upper limb.
  • Fibula bone is an ideal spare bone for a bone graft.

Structure

The bone has a shaft, and two ends, upper & lower.

Fibula Bone

Upper End or Head

  • Slightly expanded in all directions.
  • Superior surface bears a circular articular facet which articulates with the lateral condyle of the tibia.
  • Apex of the head (styloid process) projects upwards from its posterolateral aspect.

The constriction immediately below the head is known as the neck of the fibula.

Shaft

  • Considerable variable in its form because it is moulded according the muscles attached to it.
  • Three borders: Anterior, posterior, & interosseous.
  • Three surfaces: Medial, lateral, & posterior.

Lower End or Lateral Malleolus

  • Tip of the lateral malleolus is 0.5 cm lower than that of the medial malleolus.
  • Its anerior surface is 1.5 cm posterior to that of the medial malleolus.
  • Four surfaces: Anterior, posterior, lateral, & medial.

Side Determination

  • Upper end, or head, is slightly expanded in all directions.
  • Lower end or lateral malleolus is expanded anteroposteriorly and is flattened from side to side.
  • Medial side of the lower end bears a triangular articular facet anteriorly, and a deep or malleolar fossa posteriorly.

Attachments on Fibula

1. Shaft

Shaft provides the attachment to the following:

Medial surface

  • Extensor digitorum longus
  • Extensor hallucis longus
  • Peroneus tertius

Posterior surface

  • Tibialis posterior
  • Soleus
  • Flexor hallucis longus

Lateral surface

  • Peroneus longus
  • Peroneus brevis

Anterior border

  • Anterior intermuscular septum of the leg
  • Superior extensor retinaculum
  • Superior peroneal retinaculum

Posterior border

  • Posterior intermuscular septum

Interosseous border

  • Interosseous membrane

Triangular area above the medial surface of the lateral malleolus

  • Interosseous tibiofibular ligament, in the middle
  • Anterior tibiofibular ligament, anteriorly
  • Posterior tibiofibular, posteriorly

2. Head : It provides the attachment to the following :

  • Biceps femoris
  • Extensor digitorum
  • Peroneus longus
  • Soleus

3.  Capsular ligament of the superior tibiofibular joint is attached around the articular facet.

Blood Supply

  • Peroneal artery

Ossification

Fibula ossifies from one primary and two secondary centres.

  • Primary centre for the shaft appears during the 8th week of intrauterine life.
  • A secondary centre for the lower end appears during the 1st year, and fuses with the shaft by about 16 years.
  • A secondary centre for the upper end appears during the 4th year, and fuses with the shaft by about 18 years.

Fibula violates the law of ossification because the secondary centre which appears first in the lower end does not fuse last. The reasons for this violation are:

  • Secondary centre appears first in the lower end because it is a pressure epiphysis
  • Upper epiphysis fuses last because this is the growing end of the bone.

Function

  • Though fibula does not bear any weight, the lateral malleolus and the ligaments attached to it are very important in maintaining stability at the ankle joint.

Clinical Anatomy

1. Palpation

  • Upper and lower ends of the fibula are subcutaneous and palpable.

2. Nerve Injury

  • Common peroneal nerve can be rolled against the neck of the fibula. This nerve is commonly injured here.

3. Pott’s fracture

  • In the first stage of Pott’s fracture, the lower end of the fibula is fractured spirally.
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