{"schemaVersion":1,"id":"en-hub-articulations","type":"hub","pillar":"body","locale":"en","translationGroupId":"hub-articulations","slugPath":"body/joints","title":"The joints","shortTitle":"Joints","summary":"Six pages, and one question asked six times: what does this joint give up, and for what? No two answer it the same way.","level":"beginner","estimatedMinutes":3,"synonyms":["joints","shoulder","hip","knee","ankle","elbow","lumbar spine"],"blocks":[{"id":"b1","type":"paragraph","content":[{"kind":"text","value":"A muscle page describes a motor. A joint page describes a "},{"kind":"strong","value":"trade-off"},{"kind":"text","value":": every degree of mobility gained is paid for in restraint, and the other way round. The six joints described here do not settle that trade-off the same way, and that is what makes them comparable."}]},{"id":"b2","type":"heading","level":2,"text":"The two extremes","anchor":"the-two-extremes"},{"id":"b3","type":"paragraph","content":[{"kind":"text","value":"The "},{"kind":"link","value":"shoulder","href":"/en/body/joints/shoulder","external":false},{"kind":"text","value":" and the "},{"kind":"link","value":"hip","href":"/en/body/joints/hip","external":false},{"kind":"text","value":" have the same shape — a ball in a socket — and the opposite choice. The shoulder trades stability for the widest range in the body; the hip does the reverse, with a deep socket gripping the head of the femur."}]},{"id":"b4","type":"heading","level":2,"text":"The ones that depend on something other than their shape","anchor":"the-ones-that-depend-on-something-other-than-their-shape"},{"id":"b5","type":"paragraph","content":[{"kind":"text","value":"The "},{"kind":"link","value":"knee","href":"/en/body/joints/knee","external":false},{"kind":"text","value":" has neither the hip's stability nor the shoulder's range from its geometry: it depends entirely on its ligaments and menisci."}]},{"id":"b6","type":"paragraph","content":[{"kind":"text","value":"The "},{"kind":"link","value":"ankle","href":"/en/body/joints/ankle","external":false},{"kind":"text","value":" owes its reputation to an asymmetry — its outer ligaments are far thinner than the inner ones."}]},{"id":"b7","type":"heading","level":2,"text":"The ones that add up","anchor":"the-ones-that-add-up"},{"id":"b8","type":"paragraph","content":[{"kind":"text","value":"The "},{"kind":"link","value":"lumbar spine","href":"/en/body/joints/lumbar-spine","external":false},{"kind":"text","value":" moves only a few degrees per level. It is their sum that gives the trunk its range, and that distribution explains more than a global figure does."}]},{"id":"b9","type":"paragraph","content":[{"kind":"text","value":"The "},{"kind":"link","value":"elbow","href":"/en/body/joints/elbow","external":false},{"kind":"text","value":" houses two mechanisms in one capsule: a hinge and a pivot."}]},{"id":"b10","type":"heading","level":2,"text":"What stops them","anchor":"what-stops-them"},{"id":"b11","type":"paragraph","content":[{"kind":"text","value":"One cross-cutting page ties them together: "},{"kind":"link","value":"what limits range of motion","href":"/en/body/what-limits-range-of-motion","external":false},{"kind":"text","value":" separates the four things that can stop a movement, and explains why one instruction produces different positions in different people. "},{"kind":"link","value":"Proprioception","href":"/en/body/systems/proprioception","external":false},{"kind":"text","value":" supplies part of the answer: what often stops a stretch is not a mechanical stop but a sensation."}]},{"id":"b12","type":"paragraph","content":[{"kind":"text","value":"On the material side, "},{"kind":"link","value":"cartilage","href":"/en/body/cartilage","external":false},{"kind":"text","value":" and "},{"kind":"link","value":"bone","href":"/en/body/bone","external":false},{"kind":"text","value":" describe what those surfaces are made of."}]},{"id":"b13","type":"shapierAction","actionId":"dossier-recuperation-mobilite","label":"Put mobility and recovery into practice","description":"Putting mobility and recovery work together into a routine happens in Shapier; Body Lab only explains what each joint trades, and why.","webTarget":"https://shapier.app/en/dossiers/recuperation-mobilite","appTarget":"shapier://dossiers/recuperation-mobilite"},{"id":"b14","type":"relatedContent","title":"The six joints","targetIds":["en-anatomy-shoulder-joint","en-anatomy-hip-joint","en-anatomy-knee-joint","en-anatomy-ankle-joint","en-anatomy-lumbar-spine","en-anatomy-elbow-joint","en-mechanism-range-of-motion"]}],"relations":[],"authors":["equipe-editoriale-shapier"],"reviewers":["Thanh Chau"],"references":[],"review":{"publishedAt":"2026-08-02","reviewedAt":"2026-08-02","reviewDueAt":"2027-08-02"},"limitations":["This index page describes how a set is organised; the anatomical descriptions, their sources and their limits sit on the pages themselves.","None of these pages assesses an individual situation. Joint pain that persists, that follows an impact or that comes with swelling belongs to a health professional."],"seo":{"title":"The joints — six trade-offs between mobility and restraint","description":"An index of Body Lab's joint pages: shoulder, hip, knee, lumbar spine, elbow and ankle, and what each one trades for what.","canonicalPath":"/en/body/joints","image":"/og/en/hub-articulations.png"},"app":{"offlineEligible":true},"version":1}