periosteum n 1: a dense fibrous membrane covering the surface of bones (except at their extremities) and serving as an attachment for tendons and muscles; contains nerves and blood vessels that nourish the enclosed bone
Periosteum \Per`i*os"te*um\, n. [NL., fr. Gr. perio`steos round the bones; peri` around + 'oste`on a bone: cf. L. periosteon.] (Anat.) The membrane of fibrous connective tissue which closely invests all bones except at the articular surfaces. [1913 Webster]