: the membrane of connective tissue that closely invests all bones except at the articular surfaces
Illustration of PERIOSTEUM
Dense membrane over bones. The outer layer contains nerve fibres and many blood vessels, which supply cells in the bone. The bone-producing cells of the inner layer are most prominent in fetal life and early childhood, when bone formation is at its peak. In adulthood they are less active but vital to continuous bone remodeling. When bone is injured, they multiply profusely to produce new bone.