periosteum

periosteal, periosteous, adj.periosteally, adv.
/per'ee os"tee euhm/, n., pl. periostea /-tee euh/. Anat.
the normal investment of bone, consisting of a dense, fibrous outer layer, to which muscles attach, and a more delicate, inner layer capable of forming bone.
[1590-1600; < NL, var. of LL periosteon, n. use of neut. of Gk periósteos around the bones. See PERI-, OSTEO-]

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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.

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      dense fibrous membrane covering the surfaces of bones (bone), consisting of an outer fibrous layer and an inner cellular layer (cambium). The outer layer is composed mostly of collagen and contains nerve fibres that cause pain when the tissue is damaged. It also contains many blood vessels, branches of which penetrate the bone to supply the osteocytes (osteocyte), or bone cells. These perpendicular branches pass into the bone along channels known as Volkmann canals to the vessels in the haversian canals, which run the length of the bone. Fibres from the inner layer also penetrate the underlying bone, serving with the blood vessels to bind the periosteum to the bone as Sharpey fibres.

      The inner layer of the periosteum contains osteoblasts (osteoblast) (bone-producing cells) and is most prominent in fetal life and early childhood, when bone formation is at its peak. In adulthood these cells are less evident, but they retain their functional capacities and are vital to the constant remodeling of bone that goes on throughout life. In the event of bone injury, they proliferate greatly to produce new bone in the repair process. Following an injury such as a fracture, the periosteal vessels bleed around the traumatized area, and a clot forms around the fragments of bone. Within two days the osteoblasts multiply, and the cambium expands to become many cell layers thick. The cells then begin to differentiate and lay down new bone between the ends of the fracture.

      The periosteum covers all surfaces of the bone except for those capped with cartilage, as in the joints (joint), and sites for attachment of ligaments (ligament) and tendons (tendon). Fibrous cartilage often takes the place of the periosteum along grooves where tendons exert pressure against the bone. The periosteum on the inner surface of the skull is also modified to some extent as it joins the dura mater, the membrane protecting the brain.

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Universalium. 2010.

Look at other dictionaries:

  • periosteum — 1590s, from Mod.L. periosteum, L. periosteon (c.420), from Gk. periosteon, neut. of periosteos “round the bones,” from peri (see PERI (Cf. peri )) + osteon (see OSSEOUS (Cf. osseous)) …   Etymology dictionary

  • Periosteum — Per i*os te*um, n. [NL., fr. Gr. ? round the bones; ? around + ? a bone: cf. L. periosteon.] (Anat.) The membrane of fibrous connective tissue which closely invests all bones except at the articular surfaces. [1913 Webster] …   The Collaborative International Dictionary of English

  • Periostĕum — (gr.), die Knochenhaut. Periostītis, Knochenhautentzündung; Periostōse, oberflächliche Knochengeschwulst …   Pierer's Universal-Lexikon

  • Periosteum — Periosteum, griech., die Knochenhaut; Periostosis, Knochengeschwulst …   Herders Conversations-Lexikon

  • periosteum — [per΄ē äs′tē əm] n. pl. periostea [per΄ē äs′tēə] [ModL < L periosteon < Gr < peri , around + osteon, bone: see OSTEO ] the membrane of tough, fibrous connective tissue covering all bones except at the joints periosteal [per΄ē äs′tēəl]… …   English World dictionary

  • Periosteum — Infobox Anatomy Name = Periosteum Latin = GraySubject = GrayPage = Caption = compact spongy bone Caption2 = Meninges of the CNS System = MeshName = MeshNumber = DorlandsPre = p 13 DorlandsSuf = 12628368 Periosteum is a membrane that lines the… …   Wikipedia

  • Periosteum — 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… …   Medical dictionary

  • periosteum — 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… …   The new mediacal dictionary

  • Periosteum — antkaulis statusas T sritis gyvūnų anatomija, gyvūnų morfologija atitikmenys: lot. Periosteum ryšiai: platesnis terminas – kaulinė dalis …   Veterinarinės anatomijos, histologijos ir embriologijos terminai

  • Periosteum — antkaulis statusas T sritis gyvūnų raida, augimas, ontogenezė, embriologija atitikmenys: lot. Periosteum ryšiai: platesnis terminas – membraninė osteogenezė siauresnis terminas – kaulo kilmės sluoksnis …   Veterinarinės anatomijos, histologijos ir embriologijos terminai

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