Bones are the individual organs that make up the skeletal system, and muscles are the organs that hold those bones, and us, upright and together. There are 206 bones in the adult skeleton, and more than 700 muscles in the human body. For the Unit 3 discussion, think about a particular bone or muscle in the human body. What is its structure? How does its structure allow the body to do a particular thing? For example, how does the structure of our arm bones allow us to do handstands? Are there any muscles involved? What do they do?