{"schemaVersion":1,"id":"en-anatomy-ankle-joint","type":"anatomy","pillar":"body","locale":"en","translationGroupId":"anatomy-ankle-joint","slugPath":"body/joints/ankle","title":"The ankle","shortTitle":"Ankle","summary":"The talus is wedged between two malleoli like a tenon in a mortise. The ligaments holding it are not symmetrical, and that asymmetry explains a great deal.","level":"intermediate","estimatedMinutes":8,"synonyms":["ankle","talocrural joint","malleolus","talus","lateral ligament","sprain","deltoid ligament"],"blocks":[{"id":"b1","type":"heading","level":2,"text":"A tenon in a mortise","anchor":"a-tenon-in-a-mortise"},{"id":"b2","type":"paragraph","content":[{"kind":"text","value":"The ankle joint — the talocrural — links the tibia and fibula to the talus, the first bone of the foot. The two leg bones come down on either side and form two palpable prominences: the malleoli, medial for the tibia, lateral for the fibula."}]},{"id":"b3","type":"paragraph","content":[{"kind":"text","value":"Between them the talus is wedged. The comparison with joinery is classic and accurate: a rectangular tenon caught in a mortise, able to move in one direction only."}]},{"id":"b4","type":"definition","term":"Ankle mortise","definition":"The clamp-shaped space formed by the lower end of the tibia and the two malleoli, into which the talus engages. Its width varies by a few millimetres during movement.","alsoKnownAs":["malleolar clamp"]},{"id":"b5","type":"paragraph","content":[{"kind":"text","value":"That fit explains most of the ankle's behaviour. It is very stable in the plane of flexion — lifting and pointing the foot — and much less so in the others."}]},{"id":"b6","type":"heading","level":2,"text":"Two sides that do not match","anchor":"two-sides-that-do-not-match"},{"id":"b7","type":"paragraph","content":[{"kind":"text","value":"The ligaments holding the mortise are not symmetrical, and that is the most useful point on this page."}]},{"id":"b8","type":"list","ordered":false,"items":[[{"kind":"text","value":"On the "},{"kind":"strong","value":"medial"},{"kind":"text","value":" side, a broad, thick ligament fanning out from the tibial malleolus to the talus, the heel bone and the navicular. It is often called the deltoid ligament because of its shape."}],[{"kind":"text","value":"On the "},{"kind":"strong","value":"lateral"},{"kind":"text","value":" side, three separate and markedly thinner bands link the fibular malleolus to the talus, in front and behind, and to the heel bone."}]]},{"id":"b9","type":"paragraph","content":[{"kind":"text","value":"That asymmetry is not a design flaw: the lateral malleolus descends lower than the medial one and mechanically blocks outward movement. Restraint against inward movement therefore rests more on the ligaments — the thinner ones."}]},{"id":"b10","type":"evidence","level":"established","statement":"The medial ligament complex of the ankle is thicker and more continuous than the lateral complex, which is made of three separate bands.","detail":"Descriptive anatomy and kinesiology describe the same arrangement and the same asymmetry. What varies between studies is the relative contribution of each lateral band across foot positions.","referenceIds":["standring2020","neumann2016"]},{"id":"b11","type":"heading","level":2,"text":"What ankle range changes elsewhere","anchor":"what-ankle-range-changes-elsewhere"},{"id":"b12","type":"paragraph","content":[{"kind":"text","value":"Dorsiflexion — bringing the top of the foot closer to the shin — is not only an ankle matter. In the "},{"kind":"link","value":"squat","href":"/en/movements/squat","external":false},{"kind":"text","value":" it is what lets the knee travel over the foot; when it is lacking, the descent is limited or the trunk leans further to compensate."}]},{"id":"b13","type":"paragraph","content":[{"kind":"text","value":"That is why one squat instruction produces different positions in different people: the range available at the ankle, like the orientation of the socket at the "},{"kind":"link","value":"hip","href":"/en/body/joints/hip","external":false},{"kind":"text","value":", is not the same for everyone."}]},{"id":"b14","type":"heading","level":2,"text":"Seeing the ankle","anchor":"seeing-the-ankle"},{"id":"b15","type":"scene3d","sceneId":"articulations","title":"The ankle, bones and ligaments","intro":"The scene shows the tibia and fibula coming down onto the talus, with the tarsal bones below and the ligaments highlighted on either side. Without the 3D, the picture fits in one sentence: a part wedged between two uprights, held by a thick fan on one side and three thin cords on the other.","initialStepId":"cheville","accessibility":{"textAlternative":"A three-dimensional model of four joints from the left side of the body, presented one after another on a paper background. The shoulder shows the shoulder blade, collarbone and upper humerus in bone tones, with the joint capsule, the glenoid labrum and the glenohumeral ligaments in olive grey. The hip shows the hip bone and femur, the capsule wrapping the neck, the acetabular labrum and the three ligaments wound around it. The knee shows the femur, tibia, fibula and kneecap, with the two menisci resting on the tibial plateau, the cruciate ligaments at the centre and the collaterals on either side. The lumbar spine, seen from the side, shows the five vertebrae and the sacrum separated by five discs, with the longitudinal ligaments running in front of and behind the vertebral bodies. The joint tissues are highlighted at each step, the bones staying in the background.","structures":[{"label":"Glenoid labrum","description":"A fibrocartilaginous rim fixed around the edge of the glenoid cavity. It deepens the socket and increases the contact area with the head of the humerus, whose diameter far exceeds that of the cavity.","href":"/en/body/joints/shoulder"},{"label":"Ligaments of the hip","description":"Three bands wound around the capsule — iliofemoral, pubofemoral, ischiofemoral. They tighten as the hip extends, which allows standing without continuous muscular effort.","href":"/en/body/joints/hip"},{"label":"Cruciate ligaments","description":"Two ligaments stretched across the centre of the knee, crossing one in front of the other. They limit the tibia sliding under the femur — forwards for the anterior, backwards for the posterior.","href":"/en/body/joints/knee"},{"label":"Intervertebral discs","description":"Five discs separate the lumbar vertebrae and the sacrum. Each pairs a tough fibrous ring with a more deformable core, which spreads load and allows slight movement between two neighbouring vertebrae.","href":"/en/body/joints/lumbar-spine"},{"label":"Ligaments of the elbow","description":"Two collateral ligaments hold the elbow from the sides, and a ring encircles the head of the radius so it can pivot without leaving its place. The elbow thus combines a hinge and a pivot.","href":"/en/body/joints/elbow"},{"label":"Lateral ligaments of the ankle","description":"Three slender bands link the fibula to the talus and the heel bone. They are markedly thinner than their medial counterparts, which is why the ankle is more easily forced inwards.","href":"/en/body/joints/ankle"}],"steps":[{"id":"epaule","title":"The shoulder","body":"The head of the humerus is far wider than the socket that receives it. The glenoid labrum deepens the rim, the capsule wraps the whole, and three glenohumeral ligaments reinforce it in front. That is the price of mobility: little bone to hold, a great deal of soft tissue."},{"id":"hanche","title":"The hip","body":"Unlike the shoulder, the femoral head sits deep in the socket, which the acetabular labrum extends further. The three ligaments wind around the neck and tighten in extension: standing, they carry part of the work the muscles no longer have to supply."},{"id":"genou","title":"The knee","body":"Two poorly matched surfaces — the rounded condyles of the femur on an almost flat tibial plateau. The menisci fill the gap, the cruciates hold the tibia front to back, the collaterals hold it side to side. Remove any one of these parts and the load shifts onto the others."},{"id":"rachis-lombaire","title":"The lumbar spine","body":"Five vertebrae, five discs, and a set of ligaments running the whole height. Each level moves only a few degrees; it is their sum that gives the trunk its range. The longitudinal ligaments limit flexion and extension, the ligamenta flava close the back of the canal."},{"id":"coude","title":"The elbow","body":"The elbow does two things inside one capsule. The humerus and ulna form a hinge that flexes and extends in a single plane; the head of the radius pivots in place inside a ligamentous ring, which turns the palm over. The two collateral ligaments hold it all from the sides."},{"id":"cheville","title":"The ankle","body":"The talus is wedged between the two malleoli like a tenon in a mortise. On the inner side, a thick fan-shaped ligament; on the outer side, three markedly thinner bands. That asymmetry is no detail: it explains which way the ankle most often gives."}],"license":"Z-Anatomy et BodyParts3D — CC-BY-SA 4.0"}},{"id":"b16","type":"heading","level":2,"text":"What the model simplifies","anchor":"what-the-model-simplifies"},{"id":"b17","type":"callout","tone":"limit","title":"What the image is missing","content":[[{"kind":"text","value":"The cartilage is not represented, nor the sheaths that curve around the malleoli and in which the tendons of the "},{"kind":"link","value":"calves","href":"/en/body/muscles/calves","external":false},{"kind":"text","value":" and "},{"kind":"link","value":"tibialis anterior","href":"/en/body/muscles/tibialis-anterior","external":false},{"kind":"text","value":" slide. The syndesmosis joining tibia and fibula just above the joint does not appear either."}],[{"kind":"text","value":"Above all, the subtalar joint — beneath the talus — produces a large share of inversion and eversion, and is not depicted separately. What feels like an \"ankle\" movement is in fact spread across several levels."}]]},{"id":"b18","type":"heading","level":2,"text":"A subject that calls for care","anchor":"a-subject-that-calls-for-care"},{"id":"b19","type":"callout","tone":"caution","title":"What this page does not say","content":[[{"kind":"text","value":"Ankle sprains are among the most common injuries, and the arrangement described above explains why they most often affect the outer side. That allows no conclusion about any particular case."}],[{"kind":"text","value":"Body Lab proposes here no test, no exercise and no return-to-activity timeline. An ankle that will no longer take weight, that swells quickly, or that stays painful for several days belongs to a health professional."}]]},{"id":"b20","type":"heading","level":2,"text":"Related structures","anchor":"related-structures"},{"id":"b21","type":"paragraph","content":[{"kind":"text","value":"The ankle is pointed down by the "},{"kind":"link","value":"calves","href":"/en/body/muscles/calves","external":false},{"kind":"text","value":" and lifted by "},{"kind":"link","value":"tibialis anterior","href":"/en/body/muscles/tibialis-anterior","external":false},{"kind":"text","value":". It works in the "},{"kind":"link","value":"squat","href":"/en/movements/squat","external":false},{"kind":"text","value":", the "},{"kind":"link","value":"lunge","href":"/en/movements/lunge","external":false},{"kind":"text","value":" and in every walking step."}]},{"id":"b22","type":"heading","level":2,"text":"Sources","anchor":"sources"},{"id":"b23","type":"sourceList","title":"Main sources","referenceIds":["standring2020","neumann2016"]},{"id":"b24","type":"shapierAction","actionId":"exercises-calf-raises","label":"See the calf raise exercise","description":"Open the calf raise entry in Shapier, the exercise that works the calves by pointing the foot down.","webTarget":"https://shapier.app/en/exercises/calf-raises","appTarget":"shapier://exercises/calf-raises"},{"id":"b25","type":"quiz","title":"Check my understanding","questions":[{"id":"q1","prompt":"Why is the asymmetry of the ankle ligaments not a design flaw?","choices":[{"id":"q1c1","label":"Because the lateral malleolus descends lower and blocks outward movement: restraint against inward movement rests on the ligaments","correct":true,"explanation":"This is the arrangement the page describes: bone blocks on one side, the thin ligaments restrain on the other."},{"id":"q1c2","label":"Because three thin bands share the load better than one thick ligament","correct":false,"explanation":"A plausible idea, but the page credits this split with no advantage: it only says the lateral bands are markedly thinner and that inward restraint rests on them."},{"id":"q1c3","label":"Because the ankle is never stressed in the outward direction","correct":false,"explanation":"Outward movement is possible; it is simply blocked mechanically by the lateral malleolus, which descends lower than the medial one."}]},{"id":"q2","prompt":"When ankle dorsiflexion is lacking in the squat, what happens?","choices":[{"id":"q2c1","label":"The descent is limited or the trunk leans further to compensate","correct":true,"explanation":"Dorsiflexion lets the knee travel over the foot; without it, the page describes these two compensations."},{"id":"q2c2","label":"Nothing in particular: the same instruction produces the same position in everyone","correct":false,"explanation":"The page states the opposite: ankle range and socket orientation differ from one person to the next, and so do the positions."},{"id":"q2c3","label":"The knee travels further forward to make up for the missing range","correct":false,"explanation":"It is the reverse: without enough dorsiflexion the knee cannot travel over the foot, and the trunk does the compensating."}]},{"id":"q3","prompt":"Where does a large share of the foot's inversion and eversion movements come from?","choices":[{"id":"q3c1","label":"From the subtalar joint, beneath the talus","correct":true,"explanation":"The page notes that it produces a large share of these movements without being depicted separately in the model."},{"id":"q3c2","label":"From the talocrural joint, which drives every ankle movement","correct":false,"explanation":"Easy to believe since it is the ankle joint, but the tenon moves only in the plane of flexion; what feels like an ankle movement is spread across several levels."},{"id":"q3c3","label":"From the ligaments guiding the talus in the mortise","correct":false,"explanation":"Ligaments restrain and stabilise the talus, they do not produce movement; inversion and eversion largely come from the subtalar level."}]}]},{"id":"b26","type":"relatedContent","title":"Read next","targetIds":["en-anatomy-knee-joint","en-anatomy-tibialis-anterior","en-anatomy-elbow-joint"]}],"relations":[{"type":"uses-structure","targetId":"en-anatomy-calves"},{"type":"uses-structure","targetId":"en-anatomy-tibialis-anterior"},{"type":"produces-movement","targetId":"en-movement-squat"},{"type":"next-step","targetId":"en-anatomy-knee-joint"}],"authors":["equipe-editoriale-shapier"],"reviewers":["Thanh Chau"],"references":[{"id":"standring2020","authors":"Standring S","year":2020,"title":"Gray's Anatomy: The Anatomical Basis of Clinical Practice, 42nd edition","source":"Elsevier","kind":"book","url":"https://shop.elsevier.com/books/grays-anatomy/standring/978-0-7020-7705-0"},{"id":"neumann2016","authors":"Neumann DA","year":2016,"title":"Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation, 3rd edition","source":"Elsevier","kind":"book","url":"https://shop.elsevier.com/books/kinesiology-of-the-musculoskeletal-system/neumann/978-0-323-28753-1"}],"review":{"publishedAt":"2026-08-02","reviewedAt":"2026-08-02","reviewDueAt":"2027-08-02","evidenceLevel":"established"},"limitations":["The model shows neither the cartilage, nor the sheaths in which the tendons curve around the malleoli, nor the syndesmosis joining tibia and fibula just above the joint.","The subtalar joint, beneath the talus, produces a large share of inversion and eversion: it is not depicted separately.","Ankle sprains are common and take many forms. This page describes an anatomy: it cannot assess a sprain or decide when to resume activity.","An ankle that will no longer take weight, that swells quickly, or that stays painful for several days belongs to a health professional."],"seo":{"title":"The ankle — mortise, talus and lateral ligaments","description":"How the talus fits between the malleoli, the asymmetry between medial and lateral ligaments, and what ankle range changes about the squat.","canonicalPath":"/en/body/joints/ankle","image":"/og/en/anatomy-ankle-joint.png"},"app":{"offlineEligible":true},"version":1}