When you were a baby, you had over 300 bones in their body – as you grew, some of the bones joined up which is why you have 206 bones now.When the skeleton and muscles work together, we can move around. The skeleton has two main jobs to do – it supports us and protects our vital organs.Moving a muscle involves contracting it (pulling it) and relaxing it (letting it rest).The largest muscle is called the gluteus maximus, in your bottom. It helps you walk.If one of your tendons accidently gets pulled, it’s called a sprain.Muscles are attached to bones with tendons.Voluntary muscles are found in places like our arms and legs – we decide when we want to move them.Involuntary muscles like the heart move without us thinking about it.There are three different kinds of muscles – skeletal, smooth and cardiac.There are about 640 muscles in the human body.Muscles make up almost half of how much we weigh.

When a bone breaks, it’s called a fracture.The longest bone in your body is called the femur, which is located in your thigh.In addition to muscles, we have joints between our bones to do things like moving our arm up and down, and turning our head.Doctors can tell how healthy our bones are by measuring our bone density.We get bigger and taller when our bones grow.Bones need calcium to keep healthy – foods like milk, nuts and broccoli all have calcium in them.Bones have three parts, plus most have a substance deep inside called marrow.The main bone in our head is called the skull.Together, the bones in our body are called the skeleton.

Interactive muscle model