--- title: The human body deeper: bones, muscles and skin — a lesson of Mova's school · trees and pragmatics description: «The human body deeper: bones, muscles and skin», a lesson of the biology course of Mova's primary school, sentence by sentence with dependency trees and pragmatics. It begins: Bones are not dead sticks like the skeleton in a classroom: they are alive, with blood vessels and cells that keep rebuildi --- [Mova](https://md.mova.elamur.ai/free/en/) · [this page in HTML](https://mova.elamur.ai/free/en/corpora/school/biology/263-human-body-deeper-bones-muscles-and-skin/) [home](https://md.mova.elamur.ai/free/en/) / [corpora](https://md.mova.elamur.ai/free/en/corpora/) / [school](https://md.mova.elamur.ai/free/en/corpora/school/) / [Biology](https://md.mova.elamur.ai/free/en/corpora/school/biology/) / The human body deeper: bones, muscles… # The human body deeper: bones, muscles and skin Lesson 263 of the biology course of Mova's primary school: 19 sentences, each with its syntax tree and pragmatics. The lessons are written for Mova, and their agreed trees are part of Mova corpus 0.4 (CC BY-SA 4.0). How Mova does on its tests: [the lesson at school](https://md.mova.elamur.ai/free/en/school-run/biology/263-human-body-deeper-bones-muscles-and-skin/). - [0](https://md.mova.elamur.ai/free/en/corpora/school/biology/263-human-body-deeper-bones-muscles-and-skin/0/) — Bones are not dead sticks like the skeleton in a classroom: they are alive, with blood vessels and cells that keep rebuilding them, which is why a broken arm in a cast slowly knits back together. - [1](https://md.mova.elamur.ai/free/en/corpora/school/biology/263-human-body-deeper-bones-muscles-and-skin/1/) — A baby has about 300 bones, and many of them join together as it grows, so a grown-up ends up with 206. - [2](https://md.mova.elamur.ai/free/en/corpora/school/biology/263-human-body-deeper-bones-muscles-and-skin/2/) — Muscles can only pull, never push, so they work in pairs: when you flex your arm, the biceps shortens and bulges to bend it, and the triceps on the back pulls to straighten it again. - [3](https://md.mova.elamur.ai/free/en/corpora/school/biology/263-human-body-deeper-bones-muscles-and-skin/3/) — Your skin is your biggest organ, about 2 square metres on an adult, a living coat that keeps germs out, grows goosebumps in the cold and leaves fingerprints on the window. - [4](https://md.mova.elamur.ai/free/en/corpora/school/biology/263-human-body-deeper-bones-muscles-and-skin/4/) — In cartoons like Tom and Jerry, Tom gets flattened like a pancake or shatters into pieces and pops back into shape a second later; real bones can break, and a broken bone needs a doctor, a cast and weeks of healing. - [5](https://md.mova.elamur.ai/free/en/corpora/school/biology/263-human-body-deeper-bones-muscles-and-skin/5/) — An adult has 206 bones, but a baby has about 300, and many of them join together as the child grows. - [6](https://md.mova.elamur.ai/free/en/corpora/school/biology/263-human-body-deeper-bones-muscles-and-skin/6/) — Bones are alive, with blood vessels and cells that rebuild them, so a broken bone can heal. - [7](https://md.mova.elamur.ai/free/en/corpora/school/biology/263-human-body-deeper-bones-muscles-and-skin/7/) — The smallest bone, the stirrup in your ear, is smaller than a grain of rice. - [8](https://md.mova.elamur.ai/free/en/corpora/school/biology/263-human-body-deeper-bones-muscles-and-skin/8/) — The funny bone is not a bone but a nerve near the elbow, close to the skin, and bumping it sends a zinging feeling down the arm; the name may be a joke on the arm bone called the humerus. - [9](https://md.mova.elamur.ai/free/en/corpora/school/biology/263-human-body-deeper-bones-muscles-and-skin/9/) — You are about a centimetre taller in the morning, because the soft discs between your spine bones squash a little during the day and spring back at night; astronauts grow a few centimetres taller in space, where no gravity presses the discs down. - [10](https://md.mova.elamur.ai/free/en/corpora/school/biology/263-human-body-deeper-bones-muscles-and-skin/10/) — Muscles can only pull, not push, so they work in pairs, like the biceps that bends the arm and the triceps that straightens it. - [11](https://md.mova.elamur.ai/free/en/corpora/school/biology/263-human-body-deeper-bones-muscles-and-skin/11/) — There are over 600 muscles in the body, and the face alone has over 40, which make thousands of expressions. - [12](https://md.mova.elamur.ai/free/en/corpora/school/biology/263-human-body-deeper-bones-muscles-and-skin/12/) — People often say smiling takes fewer muscles than frowning, but it depends on the smile, and there is no good evidence either way. - [13](https://md.mova.elamur.ai/free/en/corpora/school/biology/263-human-body-deeper-bones-muscles-and-skin/13/) — The jaw muscle, the masseter, bites very hard for its size, the heart is the hardest-working muscle, and the biggest muscle is the gluteus maximus in your bottom. - [14](https://md.mova.elamur.ai/free/en/corpora/school/biology/263-human-body-deeper-bones-muscles-and-skin/14/) — Skin is the biggest organ, about 2 square metres on an adult; sunburn damages skin cells, which the body then sheds, and sun cream and a hat protect skin from harmful ultraviolet rays. - [15](https://md.mova.elamur.ai/free/en/corpora/school/biology/263-human-body-deeper-bones-muscles-and-skin/15/) — Goosebumps happen when tiny muscles pull hairs upright; in furry animals this fluffs up the fur to trap warm air or look bigger. - [16](https://md.mova.elamur.ai/free/en/corpora/school/biology/263-human-body-deeper-bones-muscles-and-skin/16/) — Fingerprints are ridges that help us grip, every person's are different, even identical twins', and koalas have fingerprints very like ours. - [17](https://md.mova.elamur.ai/free/en/corpora/school/biology/263-human-body-deeper-bones-muscles-and-skin/17/) — Fingers and toes wrinkle in the bath because nerves make them do it, perhaps for better grip in the wet, like tyre treads; a finger whose nerve is cut does not wrinkle. - [18](https://md.mova.elamur.ai/free/en/corpora/school/biology/263-human-body-deeper-bones-muscles-and-skin/18/) — Bones need calcium, for example from milk, vitamin D from sunlight, and exercise such as running and jumping to stay strong; bones weaken when they carry no weight, so astronauts lose bone strength in space unless they exercise every day. - ← previous: [The human body deeper: lungs, stomach and guts](https://md.mova.elamur.ai/free/en/corpora/school/biology/262-human-body-deeper-lungs-stomach-and-guts/) - next →: [How scientists find out: naturalists, Darwin, the microscope and wildlife filming](https://md.mova.elamur.ai/free/en/corpora/school/biology/264-how-scientists-find-out-naturalists-darwin-the-microscope-and-wildlife-filming/) - ↑ back to [Biology](https://md.mova.elamur.ai/free/en/corpora/school/biology/)