{"schemaVersion":1,"id":"en-hub-corps","type":"hub","pillar":"body","locale":"en","translationGroupId":"hub-corps","slugPath":"body","title":"The body: muscles, landmarks and functions","shortTitle":"Body","summary":"The Body pillar answers one simple question: where is a structure and what does it do? The pillar describes the major muscles and their attachments, the joints, the tissues all of that is made of, and the systems that make them work.","level":"beginner","estimatedMinutes":4,"synonyms":["anatomy","muscles","anatomical atlas","structures","human body"],"blocks":[{"id":"b1","type":"paragraph","content":[{"kind":"text","value":"The Body pillar answers a single question: where is a structure and what does it do?"}]},{"id":"b2","type":"paragraph","content":[{"kind":"text","value":"Every page starts from a muscle and works back up to the movement. Position in the body, attachment areas on the skeleton, actions produced, movements involved: the goal is not to memorise an atlas, but to recognise what is working when you push, pull, bend or stabilise."}]},{"id":"b3","type":"heading","level":2,"text":"What a page in this pillar contains","anchor":"what-a-page-in-this-pillar-contains"},{"id":"b4","type":"paragraph","content":[{"kind":"text","value":"A muscular structure only means something once it is tied to an action. The structure pages therefore follow the same progression."}]},{"id":"b5","type":"list","ordered":false,"items":[[{"kind":"text","value":"Where the muscle sits, and which landmarks let you find it on yourself."}],[{"kind":"text","value":"Its attachment areas: the term "},{"kind":"term","value":"origin and insertion","definition":"the two ends by which a muscle attaches to the skeleton"},{"kind":"text","value":" is defined the first time it appears on each page."}],[{"kind":"text","value":"What it does, described in everyday language before being named in anatomical terms."}],[{"kind":"text","value":"The movements it takes part in, with a link to the matching movement page."}],[{"kind":"text","value":"The neighbouring structures that work alongside it or produce the opposite action."}],[{"kind":"text","value":"What the 3D scene shows, and what it simplifies."}]]},{"id":"b6","type":"heading","level":2,"text":"How to work through the pillar","anchor":"how-to-work-through-the-pillar"},{"id":"b7","type":"paragraph","content":[{"kind":"text","value":"Three entry points lead to the same content, depending on what you are looking for."}]},{"id":"b8","type":"list","ordered":true,"items":[[{"kind":"strong","value":"By region."},{"kind":"text","value":" Upper body, trunk, lower body: useful when you already know where you want to look."}],[{"kind":"strong","value":"By movement."},{"kind":"text","value":" Start from a movement you know in the "},{"kind":"link","value":"Movement","href":"/en/movements","external":false},{"kind":"text","value":" pillar, then work back to the structures that produce it."}],[{"kind":"strong","value":"Through the body map."},{"kind":"text","value":" The interactive scene lets you select an area and open the matching page. An equivalent text list is always available: 3D is never the only way in."}]]},{"id":"b9","type":"paragraph","content":[{"kind":"text","value":"None of these entry points takes priority, and the pages can be read in any order. If you do not know where to start, the muscles easiest to find on yourself are the pectoralis major, the deltoid and the quadriceps."}]},{"id":"b10","type":"heading","level":2,"text":"Three indexes to find your way","anchor":"three-indexes-to-find-your-way"},{"id":"b11","type":"paragraph","content":[{"kind":"text","value":"You can also browse this pillar by family of structures. These indexes group the detailed pages without requiring you to know an exact anatomical name in advance."}]},{"id":"b12","type":"list","ordered":false,"items":[[{"kind":"link","value":"Muscles","href":"/en/body/muscles","external":false},{"kind":"text","value":": locate the major muscles, understand their attachments and connect"}]]},{"id":"b13","type":"paragraph","content":[{"kind":"text","value":"their action to the movements they help produce."}]},{"id":"b14","type":"list","ordered":false,"items":[[{"kind":"link","value":"Joints","href":"/en/body/joints","external":false},{"kind":"text","value":": identify the major joints, their degrees of freedom and the"}]]},{"id":"b15","type":"paragraph","content":[{"kind":"text","value":"structures that contribute to their stability."}]},{"id":"b16","type":"list","ordered":false,"items":[[{"kind":"link","value":"Systems","href":"/en/body/systems","external":false},{"kind":"text","value":": understand how the nervous, cardiovascular and respiratory"}]]},{"id":"b17","type":"paragraph","content":[{"kind":"text","value":"systems support movement and physical effort."}]},{"id":"b18","type":"heading","level":2,"text":"A reference model, not a portrait","anchor":"a-reference-model-not-a-portrait"},{"id":"b19","type":"paragraph","content":[{"kind":"text","value":"Body Lab describes a reference anatomy: the one taught and depicted in functional anatomy textbooks. It matches no individual's build exactly. Muscle size, fibre orientation and the extent of attachments vary from person to person, and some variants are common enough to be described as normal."}]},{"id":"b20","type":"callout","tone":"limit","title":"What these pages do not do","content":[[{"kind":"text","value":"The pages in the Body pillar assess no individual situation. They are not there to identify the source of a pain, nor to decide which exercise to do or avoid."}],[{"kind":"text","value":"Pain that persists, that wakes you at night, that follows an impact or that comes with a loss of strength is a matter for a healthcare professional, not for an anatomy page."}]]},{"id":"b21","type":"heading","level":2,"text":"The twenty-three structures of the pillar","anchor":"the-twenty-three-structures-of-the-pillar"},{"id":"b22","type":"paragraph","content":[{"kind":"text","value":"The first twelve are the prime movers of the basic movements: pushing, pulling, squatting and hinging at the hip. Six more have since joined them, of a different kind. Four belong to the deep plane — "},{"kind":"link","value":"rotator cuff","href":"/en/body/muscles/rotator-cuff","external":false},{"kind":"text","value":", "},{"kind":"link","value":"serratus anterior","href":"/en/body/muscles/serratus-anterior","external":false},{"kind":"text","value":", "},{"kind":"link","value":"iliopsoas","href":"/en/body/muscles/iliopsoas","external":false},{"kind":"text","value":" and "},{"kind":"link","value":"hip adductors","href":"/en/body/muscles/hip-adductors","external":false},{"kind":"text","value":" — and are visible on no silhouette: they orient and stabilise more than they move. The last two, "},{"kind":"link","value":"forearm muscles","href":"/en/body/muscles/forearm","external":false},{"kind":"text","value":" and "},{"kind":"link","value":"tibialis anterior","href":"/en/body/muscles/tibialis-anterior","external":false},{"kind":"text","value":", occupy the distal segments, where the force produced by the large muscles has to pass to reach the ground or the bar."}]},{"id":"b23","type":"paragraph","content":[{"kind":"text","value":"Four of them were written because the corpus named them without describing them: "},{"kind":"link","value":"gluteus medius","href":"/en/body/muscles/gluteus-medius","external":false},{"kind":"text","value":" appeared on six pages, the "},{"kind":"link","value":"rhomboids","href":"/en/body/muscles/rhomboids","external":false},{"kind":"text","value":" on five, "},{"kind":"link","value":"tensor fasciae latae","href":"/en/body/muscles/tensor-fasciae-latae","external":false},{"kind":"text","value":" on four. The "},{"kind":"link","value":"diaphragm","href":"/en/body/muscles/diaphragm","external":false},{"kind":"text","value":" came in through the same door, with a twist: one of the pages naming it did so to point out that it was missing from the scene. A last one describes not a muscle but the part linking them all to bone: "},{"kind":"link","value":"the tendon","href":"/en/body/the-tendon","external":false},{"kind":"text","value":"."}]},{"id":"b24","type":"paragraph","content":[{"kind":"text","value":"Cross-cutting pages describe no particular structure but what structures are made of. Four cover the tissues the corpus named without describing them — "},{"kind":"link","value":"bone","href":"/en/body/bone","external":false},{"kind":"text","value":", "},{"kind":"link","value":"cartilage","href":"/en/body/cartilage","external":false},{"kind":"text","value":", "},{"kind":"link","value":"the tendon","href":"/en/body/the-tendon","external":false},{"kind":"text","value":" and "},{"kind":"link","value":"fascia","href":"/en/body/fascia","external":false},{"kind":"text","value":" — and three cover what runs through every muscle: "},{"kind":"link","value":"muscle fibres","href":"/en/body/muscle-fibres","external":false},{"kind":"text","value":", "},{"kind":"link","value":"what limits range of motion","href":"/en/body/what-limits-range-of-motion","external":false},{"kind":"text","value":" and "},{"kind":"link","value":"contraction regimes","href":"/en/body/contraction-regimes","external":false},{"kind":"text","value":". The last was written for the same reason as the muscles named above: the word \"eccentric\" appeared on fourteen pages, redefined locally each time."}]},{"id":"b25","type":"heading","level":2,"text":"The systems","anchor":"the-systems"},{"id":"b26","type":"paragraph","content":[{"kind":"text","value":"Until now this hub announced that the nervous, circulatory and respiratory systems would not be covered, for want of being able to show them. The position has changed on one point, and one only: being unable to show a system does not require saying nothing about it, as long as the absence of a model is declared on every page. The precedent already existed — "},{"kind":"link","value":"fascia","href":"/en/body/fascia","external":false},{"kind":"text","value":", "},{"kind":"link","value":"cartilage","href":"/en/body/cartilage","external":false},{"kind":"text","value":" and "},{"kind":"link","value":"motor command","href":"/en/adaptations/motor-command","external":false},{"kind":"text","value":" are described without a scene and say so."}]},{"id":"b27","type":"paragraph","content":[{"kind":"text","value":"The "},{"kind":"link","value":"nervous system","href":"/en/body/systems/the-nervous-system","external":false},{"kind":"text","value":" opens the series. It was named on twenty-six pages — every muscle gives its nerve supply — without any of them saying how it is organised. Two pages extend it: "},{"kind":"link","value":"the neuron","href":"/en/body/systems/the-neuron","external":false},{"kind":"text","value":", whose signal never varies in size but only in rate, and the "},{"kind":"link","value":"neuromuscular junction","href":"/en/body/systems/the-neuromuscular-junction","external":false},{"kind":"text","value":", which closes the one missing link between the nerve command and the sliding of the filaments."}]},{"id":"b28","type":"paragraph","content":[{"kind":"text","value":"The "},{"kind":"link","value":"brain","href":"/en/body/systems/the-brain","external":false},{"kind":"text","value":" comes next, with two pages following directly from it. "},{"kind":"link","value":"Motor control","href":"/en/body/systems/motor-control","external":false},{"kind":"text","value":" shows that a fast movement is launched according to a prediction rather than steered, because feedback arrives too late to correct it. "},{"kind":"link","value":"Proprioception","href":"/en/body/systems/proprioception","external":false},{"kind":"text","value":" describes the channel supplying that feedback — the one that lets you touch your nose with your eyes closed, and that knows well where the body is but rather poorly what it is producing."}]},{"id":"b29","type":"paragraph","content":[{"kind":"text","value":"Three pages close the vital foundation. The "},{"kind":"link","value":"heart","href":"/en/body/systems/the-heart","external":false},{"kind":"text","value":" gives the Energy pillar the equation it was missing, and corrects a formula everybody applies. "},{"kind":"link","value":"Blood and circulation","href":"/en/body/systems/blood-and-circulation","external":false},{"kind":"text","value":" describes what the word \"blood\" covered across thirty-two pages. The "},{"kind":"link","value":"lungs","href":"/en/body/systems/the-lungs","external":false},{"kind":"text","value":" complete the diaphragm page and establish a fact that contradicts the sensation: in healthy adults, breath is not what limits an endurance effort."}]},{"id":"b30","type":"paragraph","content":[{"kind":"text","value":"Two pages close the series. The "},{"kind":"link","value":"endocrine system","href":"/en/body/systems/the-endocrine-system","external":false},{"kind":"text","value":" is the body's second communication network — slow and diffuse where the nerve is fast and targeted — and corrects along the way the idea that the post-session hormonal surge drives muscle growth. "},{"kind":"link","value":"Pain","href":"/en/body/systems/pain","external":false},{"kind":"text","value":" was used on forty-six pages as a border and never as a subject; it becomes one, with the distinction that matters — the signal sent is not the experience lived — and a firm reminder of what that distinction above all does not let you conclude."}]},{"id":"b31","type":"paragraph","content":[{"kind":"text","value":"Three pages finally complete the foundation. The "},{"kind":"link","value":"digestive system","href":"/en/body/systems/the-digestive-system","external":false},{"kind":"text","value":" is the backbone of the three pages on nutrients, all of which assumed a route nothing described. The "},{"kind":"link","value":"skin","href":"/en/body/systems/the-skin","external":false},{"kind":"text","value":" carries a function the corpus took for granted: shedding the heat the muscle produces. The "},{"kind":"link","value":"immune system","href":"/en/body/systems/the-immune-system","external":false},{"kind":"text","value":" says what the word \"inflammation\" covers, used by two pages without ever being defined."}]},{"id":"b32","type":"paragraph","content":[{"kind":"text","value":"Three pages close the list. The "},{"kind":"link","value":"kidneys","href":"/en/body/systems/the-kidneys","external":false},{"kind":"text","value":" are not waste filters but regulators, and they carry the answer the hydration page assumed. The "},{"kind":"link","value":"lymphatic system","href":"/en/body/systems/the-lymphatic-system","external":false},{"kind":"text","value":" is the return network three pages already invoked — the route dietary fat takes and the highway of the defence cells. "},{"kind":"link","value":"Balance","href":"/en/body/systems/balance","external":false},{"kind":"text","value":" brings together three independent pieces of information the brain must reconcile, and shows that standing is not a state but a permanent correction."}]},{"id":"b33","type":"paragraph","content":[{"kind":"text","value":"None of these pages has a scene, and each explains why. Three reasons are spread among them: the anatomical source does not contain the tissue, the scale is beyond a mesh's reach, or — for the digestive system and the kidneys — the data exists but under a licence the project cannot use."}]},{"id":"b34","type":"relatedContent","title":"The systems of the body","targetIds":["en-mechanism-nervous-system","en-mechanism-neuron","en-mechanism-neuromuscular-junction","en-mechanism-brain","en-mechanism-motor-control","en-mechanism-proprioception","en-mechanism-heart","en-mechanism-blood-circulation","en-mechanism-lungs","en-mechanism-endocrine-system","en-mechanism-pain","en-mechanism-digestive-system","en-mechanism-skin","en-mechanism-immune-system","en-mechanism-kidneys","en-mechanism-lymphatic-system","en-mechanism-balance"]},{"id":"b35","type":"heading","level":2,"text":"The six joints","anchor":"the-six-joints"},{"id":"b36","type":"paragraph","content":[{"kind":"text","value":"The joints have since joined the pillar. They follow a different logic from the muscles: what is described is not a motor but a trade-off between mobility and restraint, and that trade-off is not the same from one joint to the next."}]},{"id":"b37","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":" are the two extremes — the first trades stability for range, the second does the reverse. The "},{"kind":"link","value":"knee","href":"/en/body/joints/knee","external":false},{"kind":"text","value":" has neither by its shape and depends entirely on its ligaments and menisci. The "},{"kind":"link","value":"lumbar spine","href":"/en/body/joints/lumbar-spine","external":false},{"kind":"text","value":" moves only a few degrees per level, and it is their sum that gives the trunk its range. 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 — and 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":"b38","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."}]},{"id":"b39","type":"relatedContent","title":"The joints in the Body pillar","targetIds":["en-anatomy-shoulder-joint","en-anatomy-elbow-joint","en-anatomy-hip-joint","en-anatomy-knee-joint","en-anatomy-ankle-joint","en-anatomy-lumbar-spine","en-mechanism-range-of-motion"]},{"id":"b40","type":"paragraph","content":[{"kind":"text","value":"This pillar is the starting point for the others. Once a structure has been identified, the "},{"kind":"link","value":"Movement","href":"/en/movements","external":false},{"kind":"text","value":" pillar shows how several muscles coordinate to produce a movement, the "},{"kind":"link","value":"Adaptation","href":"/en/adaptations","external":false},{"kind":"text","value":" pillar explains how that muscle changes when it is worked repeatedly, and the "},{"kind":"link","value":"Energy","href":"/en/energy","external":false},{"kind":"text","value":" pillar describes the fuel that contraction consumes."}]},{"id":"b41","type":"shapierAction","actionId":"hub-exercises","label":"Browse exercises by muscle and movement","description":"Finding the exercises that work a given structure is done in Shapier; Body Lab only explains where that structure sits and what it does.","webTarget":"https://shapier.app/en/exercises","appTarget":"shapier://exercises"},{"id":"b42","type":"relatedContent","title":"All the structures in the Body pillar","targetIds":["en-anatomy-pectoralis-major","en-anatomy-deltoids","en-anatomy-triceps-brachii","en-anatomy-biceps-brachii","en-anatomy-latissimus-dorsi","en-anatomy-trapezius","en-anatomy-erector-spinae","en-anatomy-abdominal-wall","en-anatomy-glutes","en-anatomy-quadriceps","en-anatomy-hamstrings","en-anatomy-calves","en-anatomy-rotator-cuff","en-anatomy-serratus-anterior","en-anatomy-iliopsoas","en-anatomy-hip-adductors","en-anatomy-forearm","en-anatomy-tibialis-anterior","en-anatomy-gluteus-medius","en-anatomy-rhomboids","en-anatomy-tensor-fasciae-latae","en-anatomy-diaphragm","en-anatomy-tendon","en-mechanism-muscle-fibres","en-mechanism-contraction-regimes","en-mechanism-fascia","en-mechanism-bone","en-mechanism-cartilage"]}],"relations":[],"authors":["equipe-editoriale-shapier"],"reviewers":["Thanh Chau"],"references":[],"review":{"publishedAt":"2026-08-02","reviewedAt":"2026-08-02","reviewDueAt":"2027-08-02"},"limitations":["This entry page describes how the pillar is organised; the detailed anatomical descriptions, their sources and their limits sit on the pages themselves."],"seo":{"title":"Body — functional anatomy of the major muscles","description":"The entry point to the Body pillar of Body Lab: muscles, joints, tissues and systems — where each structure sits and what it is for.","canonicalPath":"/en/body","image":"/og/en/hub-corps.png"},"app":{"offlineEligible":true},"version":1}