# How Muscles Move Bones

Understand that muscles work in pairs to move bones: when one muscle contracts (gets shorter and pulls), the opposite muscle relaxes, and that some muscles are voluntary (we choose to use them) while others like the heart are involuntary (they work automatically)

Builds on: Naming Major Bones (soft, https://ai.page/c/naming-major-bones/en.md), Bones & Muscles (hard, https://ai.page/c/bones-and-muscles/en.md)

Concept id: how-muscles-move-bones. Subject: science. Licence: CC BY-SA 4.0.

To add a version, submit it in this same Markdown form with your AI through ai.page's connector (submit_version). Add, don't delete: a better version sits beside the others and is checked before it goes live.