Gastrocnemius tendon (outer head) !
The outer gastrocnemius tendon anchors the outer head of the calf muscle to the back of the femur, just above the knee.
Official name: Tendon of lateral head of gastrocnemius
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What it is
The upper tendon of the outer calf muscle head, on the back of the femur.
What it does
Anchors the calf muscle above the knee.
Key facts
- Attaches
- Origin tendon of the lateral head on the lateral surface of the lateral femoral condyle; may hold a fabella (sesamoid bone)
- Function
- Anchors the lateral head above the knee (knee flexion and ankle plantarflexion); forms the inferolateral border of the popliteal fossa
- Tight in
- Knee extension with ankle dorsiflexion
Relations
- Superficial
- Biceps femoris tendon, with the common fibular nerve between them
- Medial
- Plantaris, which arises just above it, then the popliteal artery and vein between the two heads
- Deep
- Posterolateral knee joint capsule, with the popliteus tendon inside the joint beneath it
How to find it
Hard to feel; the lateral head forms the outer lower border of the popliteal fossa, under the biceps femoris tendon.
On imaging
On a lateral knee radiograph a fabella is a small, smooth, round bone behind the lateral condyle, often on both sides; MRI shows it embedded in the tendon, which separates it from a loose body.
Clinical notes
- Fabella pain syndrome and fabella fractures are rare causes of pain at the back outer knee
- In rare cases a fabella presses on the common fibular nerve
- After knee replacement, a fabella rubbing on the metal femoral condyle is a recognised cause of posterolateral pain and clicking; removing it usually relieves the symptoms
Anatomical variants
- A fabella is present in a variable share of people, with rates that differ widely between populations
- Absence of a gastrocnemius head is rare and, when seen, usually affects the lateral head
Test yourself
Think of the answer, then tap the question to see it.
What is a fabella, and where does it lie?
A normal sesamoid inside the lateral head of gastrocnemius tendon, behind the lateral femoral condyle; not a loose body or a fracture.
Which ligament runs from the fabella to the fibular head?
The fabellofibular ligament, part of the posterolateral corner.
Which border of the popliteal fossa does the lateral head of gastrocnemius form?
The inferolateral border.
Educational information, not medical advice. For any symptom, see a health professional.
Its names
- Official Latin (TA2)
- caput laterale musculi gastrocnemii TA2 2658
- Official Spanish (DeCS)
- Tendón del gemelo externo DeCS D013710
- English (TA2)
- Tendon of lateral head of gastrocnemius
- Also called
- caput fibulare musculi gastrocnemii
Related
Sources: Terminologia Anatomica (TA2); DeCS; Anatomy, Bony Pelvis and Lower Limb: Gastrocnemius Muscle.
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Representative model, for educational purposes only.
