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Bones of the Leg

Ossa cruris

For medical students3 min readUpdated 2026-10-10

The leg is formed by two long tubular bones: the massive tibia, located medially, and the slender fibula, located laterally. Together they create a rigid framework for the limb, though the distribution of functional load between them differs completely.

Bone typeLong tubular bones
MedialTibia, bears the main body mass
LateralFibula, bears almost no load

Tibia

The tibia is the main weight-bearing structure of the leg. It consists of a proximal epiphysis, a shaft, and a distal epiphysis.

The proximal epiphysis features the superior articular surface (facies articularis superior), which is divided into two large condyles: medial (condylus medialis) and lateral (condylus lateralis). Between them lies the intercondylar eminence (eminentia intercondylaris). This eminence is formed by two tubercles (medial and lateral), with the anterior and posterior intercondylar areas lying anterior and posterior to it. On the posteroinferior aspect of the lateral condyle, there is a fibular articular facet for articulation with the head of the adjacent bone.

The shaft of the tibia (corpus tibiae) has a triangular cross-section. It features three surfaces (medial, lateral, and posterior) and three borders:

On the posterior surface of the shaft (facies posterior), the soleal line (linea m. solei) runs in an arch from the interosseous border to the medial border.

The distal epiphysis extends medially into a large process, the medial malleolus (malleolus medialis). Its lateral side bears an articular surface for articulation with the talus. The lateral side of the epiphysis features the fibular notch (incisura fibularis), and the inferior surface bears the inferior articular surface.

Fibula

The fibula is a slender bone situated lateral to the tibia. It also possesses a shaft and two extremities.

Its proximal epiphysis is represented by the head (caput fibulae), which terminates superiorly in a pointed apex of the fibular head (apex capitis fibulae). On the medial side of the head is an articular surface for articulation with the lateral condyle of the tibia. The constricted region immediately below the head is called the neck (collum fibulae).

The shaft of the fibula (corpus fibulae) has three surfaces (lateral, medial, posterior) and three borders. The anterior border is the sharpest. The posterior border is rounded. The interosseous border is less prominent; it descends from the head and in the lower third merges with a well-defined medial crest (crista medialis), which runs from posterior to anterior.

The distal epiphysis forms the lateral malleolus (malleolus lateral), which is readily palpable beneath the skin on the lateral side of the leg. Its medial side features an articular surface for the talus, and its posterior surface bears a characteristic depression — the malleolar fossa (fossa malleoli lateralis).

How to Differentiate the Bones and Determine Laterality

During practical sessions, it is essential to quickly identify whether a given bone is a tibia or fibula and whether it is left or right.

For the tibia:

  1. The sharp anterior border and tuberosity must face anteriorly.
  2. The medial malleolus on the inferior end points inward (medially).
  3. The soleal line is located posteriorly.

For the fibula:

  1. The rounded head is superior (proximal), and the elongated malleolus is inferior (distal).
  2. The articular surfaces on both ends face inward (toward the tibia and the talus).
  3. The sharp border of the shaft faces anteriorly, and the malleolar fossa is located posteriorly.
FeatureTibiaFibula
PositionMedialLateral
Primary LoadBears body weightBears almost no load
Key LandmarksTuberositas tibiae, linea m. solei, medial malleolusHead with apex, neck, lateral malleolus, fossa malleoli lateralis
Interosseous BorderLocated laterallyWeakly defined, merges with crista medialis

Mnemonic

Mnemonic for positioning: «Tibia Tall/Thick» — massive bone, lies on the inside (medial). «Fibula Filamentous» — slender bone, lies on the outside (lateral).

Frequently asked questions

Which bones does the tibia articulate with?

The tibia articulates with three bones: the femur, fibula, and talus.

  • Femur — articulates with the superior articular surface of the tibia, participating in the formation of the knee joint.
  • Fibula — articulates via the fibular articular facet on the lateral condyle proximally and at the fibular notch distally.
  • Talus — articulates with the inferior articular surface and the articular surface of the medial malleolus, forming the ankle joint.
Which muscles originate from or attach to the fibula?

The fibular longus muscle (m. fibularis longus / m. peroneus longus) originates from the head and the upper part of the lateral surface of the fibula. Other specific muscles originating from the fibula are not detailed here; it primarily serves as a strut for muscle attachment.

Which ligaments attach to the anterior and posterior intercondylar areas of the tibia?

The cruciate ligaments, which ensure knee joint stability, attach to the intercondylar areas of the tibia.

  • Anterior cruciate ligament (lig. cruciatum anterius) — connects the lateral femoral condyle to the anterior intercondylar area of the tibia.
  • Posterior cruciate ligament (lig. cruciatum posterius) — attaches to the posterior intercondylar area of the tibia.
Where is the malleolar fossa located and what ligament does it serve to attach?

The malleolar fossa (fossa malleoli lateralis) is located on the posterior surface of the lateral malleolus of the distal fibular epiphysis. The provided materials do not specify which exact ligament attaches to this fossa, though it is noted as an important anatomical landmark for determining bone laterality.

Which tendons run through the malleolar sulcus on the posterior surface of the medial malleolus?

Behind the medial malleolus, the malleolar sulcus (sulcus malleolaris medialis) transmits the tendons of three leg muscles. From anterior to posterior in the retromalleolar canal:

  • Tendons of tibialis posterior (m. tibialis posterior);
  • Flexor digitorum longus (m. flexor digitorum longus);
  • Flexor hallucis longus (m. flexor hallucis longus).
Does the fibula bear body weight?

Practically no. The entire primary axial load during standing and walking is transmitted through the massive tibia. The fibula serves primarily for muscle attachment and forming the lateral part of the ankle joint.

Where is the soleal line located?

It is located on the posterior surface of the tibial shaft (corpus tibiae), slightly inferior to the proximal epiphysis, running in an arch from the interosseous border to the medial border.

How to quickly locate the intercondylar eminence?

It is found on the proximal epiphysis of the tibia, right on the superior articular surface between the medial and lateral condyles.

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