Bones are the solid, firm structures that make up the vertebrate skeleton. They are complex living organs that form the supportive framework of the body and are comprised of mineral matrix, marrow, blood vessels, nerves, and cartilage. A typical [Page 118]adult human body has 206 distinct bones with the largest bone (femur) in the thigh and smallest (stapes) inside the ear.

Bones, together with skeletal muscles, tendons, and joints, allow three-dimensional movement of the body. They provide protection to multiple internal organs, for example, lungs and heart inside the rib cage. Bone marrow is the site of production of all types of blood cells (a process called hematopoiesis). Another function is the storage of nutrients: lipids, serving as a reservoir for energy; and minerals, especially calcium ...