[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anatomy](https://durgical.com/en/anatomy/) › [Lower limb](https://durgical.com/en/anatomy/region/lower-limb/) › Ankle tendon sheaths [Muscular system](https://durgical.com/en/anatomy/system/muscular-system/) · [Lower limb](https://durgical.com/en/anatomy/region/lower-limb/) # Ankle tendon sheaths The ankle tendon sheaths are slippery tubes around the tendons that cross the ankle, so they glide smoothly. Official name: Anterior tarsal tendon sheaths [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=lower_limb&select=ankle_tendon_sheaths&side=r) Opens in the Durgical app, no sign-up needed. ## What it is Slippery, fluid-filled tubes around the tendons that cross the ankle at the front, the inner side and the outer side. ## What it does Let the tendons glide smoothly under the retinacula and around the ankle bones. ## Key points - Behind the medial malleolus, front to back: tibialis posterior, flexor digitorum longus, [posterior tibial artery](https://durgical.com/en/anatomy/posterior-tibial-artery/) and veins, tibial nerve, flexor hallucis longus - The fibularis longus and brevis tendons share one sheath behind the lateral malleolus that splits in two lower down; brevis lies against the bone - Tibialis posterior tenosynovitis is an early stage of adult acquired flatfoot ## Key facts **Where** Under retinacula: anterior (TA, EHL, EDL), medial (TP, FDL, FHL), lateral (common sheath of fibularis longus and brevis) **Function** Synovial sheaths that let tendons glide under retinacula and around malleoli; site of tenosynovitis ## Relations **In front** Under the [extensor retinacula](https://durgical.com/en/anatomy/superior-extensor-retinaculum-of-ankle/), medial to lateral: [tibialis anterior](https://durgical.com/en/anatomy/tibialis-anterior-muscle/), [extensor hallucis longus](https://durgical.com/en/anatomy/extensor-hallucis-longus/), [extensor digitorum longus](https://durgical.com/en/anatomy/extensor-digitorum-longus/) with [fibularis tertius](https://durgical.com/en/anatomy/fibularis-tertius-muscle/); the [anterior tibial artery](https://durgical.com/en/anatomy/anterior-tibial-artery/) and [deep fibular nerve](https://durgical.com/en/anatomy/deep-fibular-nerve/) lie between EHL and EDL **Medial** Under the flexor retinaculum (tarsal tunnel): [tibialis posterior](https://durgical.com/en/anatomy/tibialis-posterior-muscle/), [flexor digitorum longus](https://durgical.com/en/anatomy/flexor-digitorum-longus/), the [tibial nerve](https://durgical.com/en/anatomy/tibial-nerve/) with the posterior tibial vessels, [flexor hallucis longus](https://durgical.com/en/anatomy/flexor-hallucis-longus/) **Lateral** Under the superior and inferior [fibular retinacula](https://durgical.com/en/anatomy/superior-fibular-retinaculum/): the common sheath of [fibularis brevis](https://durgical.com/en/anatomy/fibularis-brevis-muscle/) (closer to the [fibula](https://durgical.com/en/anatomy/fibula/)) and [fibularis longus](https://durgical.com/en/anatomy/fibularis-longus-muscle/); the [sural nerve](https://durgical.com/en/anatomy/sural-nerve/) runs nearby ## How to find it Each tendon is found by resisting its action: tibialis anterior stands out in front with dorsiflexion and inversion; tibialis posterior is felt just behind the medial malleolus with resisted inversion; the fibular tendons are felt behind the lateral malleolus with resisted eversion. Sheath swelling follows the tendon's line. ## Examination - Single-heel-rise test: failure to rise on tiptoe on one leg, or the heel not swinging into varus, suggests tibialis posterior dysfunction - Too-many-toes sign: seen from behind, more toes visible lateral to the heel on the affected side in adult acquired flatfoot - Resisted eversion with the ankle dorsiflexed that makes the fibular tendons snap forward over the lateral malleolus shows subluxation from a torn superior fibular retinaculum ## On imaging Ultrasound, including dynamic scanning, shows sheath fluid, synovial thickening, tears and tendon subluxation; MRI shows tenosynovitis and longitudinal split tears. A little fluid in the flexor hallucis longus sheath can be normal because it may communicate with the ankle joint. ## Common problems - Tenosynovitis: painful swelling of a sheath from overuse, injury or inflammatory arthritis. ## Clinical notes - Fibularis brevis split tear: the tendon is squeezed between fibularis longus and the fibular groove - Flexor hallucis longus tenosynovitis in ballet dancers, behind the medial malleolus, often with an os trigonum and posterior ankle impingement - Tarsal tunnel syndrome: the tibial nerve is compressed under the flexor retinaculum, sometimes by tenosynovitis or a ganglion from a sheath ## Anatomical variants - Os peroneum, a sesamoid bone in the [fibularis longus tendon](https://durgical.com/en/anatomy/tendon-of-fibularis-longus/) near the [cuboid](https://durgical.com/en/anatomy/cuboid-bone/), is common and can fracture or cause lateral foot pain - An extra muscle, fibularis quartus, can crowd the fibular tendons behind the lateral malleolus ## Memory aid Behind the medial malleolus, front to back: "Tom, Dick And Very Nervous Harry" (Tibialis posterior, flexor Digitorum longus, Artery, Vein, Nerve, flexor Hallucis longus). ## Related conditions - [Tarsal tunnel syndrome](https://durgical.com/en/conditions/tarsal-tunnel-syndrome/) - [Chikungunya](https://durgical.com/en/conditions/chikungunya/) ## Test yourself Think of the answer, then tap the question to see it. ## What lies behind the medial malleolus, from front to back? Tibialis posterior, flexor digitorum longus, posterior tibial artery and veins, tibial nerve, flexor hallucis longus. ## How are the fibularis tendon sheaths arranged behind the lateral malleolus? Fibularis longus and brevis share one sheath that splits in two lower down; the brevis lies against the bone. ## Which tenosynovitis is an early stage of adult acquired flatfoot, and which test checks it? Tibialis posterior tenosynovitis; the single-heel-rise test fails or the heel does not swing into varus. ## Which tenosynovitis is typical of ballet dancers behind the medial malleolus? Flexor hallucis longus tenosynovitis, often with an os trigonum and posterior ankle impingement. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/anatomy/anterior-tarsal-tendon-sheaths/) Educational information, not medical advice. For any symptom, see a health professional. ## Its names **Official Latin (TA2)** vaginae tarseae anteriores tendinum; vaginae tarseae tibiales tendinum; vaginae tarseae fibulares tendinum TA2 2755 **Official Spanish (DeCS)** Vainas tendinosas tarsianas anteriores, tibiales y fibulares **English (TA2)** Anterior tarsal tendon sheaths ## Related - [Tibialis posterior tendon](https://durgical.com/en/anatomy/tendon-of-tibialis-posterior/) - [Fibularis longus tendon](https://durgical.com/en/anatomy/tendon-of-fibularis-longus/) - [Tibialis anterior tendon](https://durgical.com/en/anatomy/tendon-of-tibialis-anterior/) Sources: Terminologia Anatomica (TA2); [Anatomy, Bony Pelvis and Lower Limb: Foot and Ankle](https://www.ncbi.nlm.nih.gov/books/NBK546698/). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/anatomy/anterior-tarsal-tendon-sheaths/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/anterior-tarsal-tendon-sheaths/