Bone structure refers to the complex arrangement of cells, tissues, and minerals that make up bones in the human body. Bones are primarily composed of a hard outer layer called cortical bone, which provides strength, and a spongy inner layer known as trabecular bone, which helps absorb shock. The main mineral found in bones is calcium phosphate, which gives them their rigidity. Bones are also living tissues that contain cells called osteoblasts for bone formation and osteoclasts for bone resorption. They are surrounded by a protective layer called periosteum, which contains blood vessels and nerves. Together, these components allow bones to support the body, protect vital organs, and facilitate movement.