- The periosteum is a dense membrane composed of fibrous connective tissue that closely wraps (invests) all bone, except that of the articulating surfaces in joints which are covered by a synovial membrane. "Peri-" is a prefix borrowed from the Greek meaning "around or about" and "-osteum" also comes from the Greek, from "osteon" meaning "bone", so periosteum literally means "around the bone."
* * *The thick fibrous membrane covering the entire surface of a bone except its articular cartilage. In young bones, it consists of two layers: an inner cellular layer that is osteogenic, forming new bone tissue, and an outer fibrous connective tissue layer conveying the blood vessel s and nerves supplying the bone; in older bones, the osteogenic layer is reduced. SEE ALSO: perichondral bone. SYN: periost. [Mod. L. fr. G. periosteon, ntr. of adj. periosteos, around the bones, fr. peri, around, + osteon, bone]- p. cranii [TA] SYN: pericranium.
* * *peri·os·te·um -tē-əm n, pl -tea -tē-ə the membrane of connective tissue that closely invests all bones except at the articular surfaces
* * *n.a layer of dense connective tissue that covers the surface of a bone except at the articular surfaces. The outer layer of the periosteum is extremely dense and contains a large number of blood vessels. The inner layer is more cellular in appearance and contains osteoblasts and fewer blood vessels. The periosteum provides attachment for muscles, tendons, and ligaments.
* * *peri·os·te·um (per″e-osґte-əm) [peri- + Gr. osteon bone] [TA] a specialized connective tissue covering all bones of the body, and possessing bone-forming potentialities; in adults, it consists of two layers that are not sharply defined, the external layer being a network of dense connective tissue containing blood vessels, and the deep layer composed of more loosely arranged collagenous bundles with spindle-shaped connective tissue cells and a network of thin elastic fibers. periosteal adj
Medical dictionary. 2011.