Extensor retinacula !

The extensor retinacula are bands across the front of the ankle that hold the front tendons close to the bone.

Official name: Superior extensor retinaculum of ankle

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What it is

Two bands across the front of the ankle: one above the joint and a Y-shaped one below it.

What it does

Hold the front tendons close to the bones so they pull efficiently when the ankle bends.

Key facts

Attaches: Superior: anterior borders of tibia and fibula above ankle; inferior (Y-shaped): calcaneus to medial malleolus and plantar fascia
Function: Hold tibialis anterior, EHL, EDL and fibularis tertius tendons to ankle; prevent bowstringing

Relations

Contents: Medial to lateral: tibialis anterior tendon, extensor hallucis longus, anterior tibial artery (becoming the dorsalis pedis artery) with its veins and the deep fibular nerve, toe extensor tendons and fibularis tertius
Superficial: Branches of the superficial fibular nerve crossing over them; medially, the great saphenous vein and saphenous nerve in front of the medial malleolus
Deep: Ankle joint capsule, talar neck and the tendon sheaths
Lateral: The stem of the inferior retinaculum anchors in the sinus tarsi and continues into the inferior fibular retinaculum

How to find it

The superior band lies a few centimetres above the ankle joint line between the tibia and fibula; the inferior band crosses the front of the ankle and top of the talus. When the foot and toes are lifted, the tendons bulge between and beyond the bands.

Examination

Tinel sign over the deep fibular nerve under the inferior retinaculum: tingling into the first web space suggests anterior tarsal tunnel syndrome

On imaging

Ultrasound and MRI show the superior and inferior extensor retinacula as thin dark bands across the extensor tendons in front of the ankle. Look for thickening or a tear after a sprain and sheath fluid beneath. In anterior tarsal tunnel syndrome, imaging looks for what presses on the deep fibular nerve, such as a dorsal talonavicular osteophyte or a ganglion; radiographs show the spurs.

Common problems

Tight shoes or laces over the lower band can press on the deep fibular nerve (anterior tarsal tunnel).

Clinical notes

Anterior tarsal tunnel syndrome: numbness in the first web space and, in long-standing cases, wasting of the extensor digitorum brevis; causes include tight laces, osteophytes and ganglia
If the retinaculum is torn or released, the tibialis anterior tendon can bowstring across the front of the ankle
Anterior ankle arthroscopy portals sit medial to the tibialis anterior and lateral to the fibularis tertius; the lateral portal is close to the superficial fibular nerve

Anatomical variants

Some texts describe an extra upper-lateral band of the inferior retinaculum, so that it looks X-shaped rather than Y-shaped

Memory aid

Under the extensor retinacula, medial to lateral: "The Hospitals Are Not Dirty Places" (Tibialis anterior, Hallucis longus, Artery, Nerve, Digitorum longus, Peroneus tertius).

Test yourself

Think of the answer, then tap the question to see it.

What is the shape of the inferior extensor retinaculum, and where are its limbs attached?

Y-shaped: the stem anchors in the sinus tarsi and calcaneus, an upper limb reaches the medial malleolus and a lower limb blends with the plantar fascia.

What is anterior tarsal tunnel syndrome?

Compression of the deep fibular nerve under the inferior extensor retinaculum, giving numbness in the first web space.

What happens to the tibialis anterior tendon if the extensor retinaculum is torn or released?

It can bowstring across the front of the ankle.

Which nerve is close to the lateral portal of anterior ankle arthroscopy?

The superficial fibular nerve; the lateral portal sits lateral to the fibularis tertius.

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Educational information, not medical advice. For any symptom, see a health professional.

Its names

Official Latin (TA2): retinaculum extensorium superius tali; retinaculum extensorium inferius tali TA2 2712
Official Spanish (DeCS): Retináculos extensores superior e inferior del tobillo
English (TA2): Superior extensor retinaculum of ankle
Also called: transverse crural ligament · cruciate crural ligament · ligamentum transversum cruris

Sources: Terminologia Anatomica (TA2); Anatomy, Bony Pelvis and Lower Limb: Leg Anterior Compartment.

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Representative model, for educational purposes only.

Extensor retinacula highlighted on the Durgical 3D model