1. the hard, rigid form of connective tissue constituting most of the skeleton of most vertebrates, composed chiefly of an organic component of collagenous matrix and cells and a mineral component of calcium phosphate and other salts.
2. any distinct piece of the skeleton of the body. For a named list of bones
3. describes conformation, substance, thickness and quality of bone structure in an animal, e.g. an animal with good bone. See also osseous.
- b. ash — analysis of the degree of mineralization of bone is done by an ash analysis in which the bone is heated at 600°C until there is no further weight loss.
- b. atrophy — see osteoporosis.
- brittle b's — see osteogenesis imperfecta.
- b. callus — see callus (2).
- cancellated b., cancellous b. — bone composed of thin intersecting lamellae, usually found internal to compact bone. Called also spongy bone.
- cartilage b. — bone developing within cartilage, ossification taking place within a cartilage model. Called also endochondral ossification.
- b. cells — see osteocyte, osteoclast, osteoblast.
- cheek b. — see zygomatic bone.
- chevron b. — see hemal arch.
- chondroid b. — has histological characteristics of both cartilage and bone; may develop in response to tensions from frequently changing directions.
- b. clamp — strongly built, handheld, tong-like instrument with outcurving blades making a circle when closed for grasping a piece of bone shaft. The handles are ratcheted to give a firm grasp, and the faces of the blades have deep, crossways grooves.
- compact b. — bone substance that is dense and noncancellous.
- cortical b. — the compact bone of the shaft of a bone that surrounds the marrow cavity.
- b. cyst — a discrete, grossly visible cavity, filled with fluid and often lined by a membrane. It may be located under cartilage (subchondral), be a single cavity (unicameral), filled with blood (aneurysmal) or contain epidermal cells (epidermoid).
Aneurysmal bone cyst. By permission from Slatter D, Textbook of Small Animal Surgery, Saunders, 2002 - decalcified b. — a material for bone grafting. Prepared by treatment with hydrochloric acid, bone morphogenic protein is retained.
- b. density — the degree of mineralization, usually demonstrable in radiographs.
- b. discoloration — continuous intake of tetracycline colors bone of growing animals yellow; inherited or acquired porphyria discolors bone red-brown.
- ectopic b. — bone which develops in abnormal sites. Needs to be differentiated from ectopic ossification and ectopic mineralization.
- endochondral b. — bone formed by the ossification of cartilage. The means of lengthening of long bones. See also enchondral ossification.
- entoglossal b. — the bone in a bird's tongue.
- b. file, b. rasp — see bone rasp.
- flat b. — one whose thickness is slight, sometimes consisting of only a thin layer of compact bone, or of two layers with intervening cancellated bone and marrow; usually curved rather than flat.
- b. flour — finely ground bone used as a mineral supplement in animal feed to supply additional calcium and phosphorus. Needs to be properly sterilized.
- b. fragility — the ease with which bone fractures depends to a large extent on the density of its compact bone, that is its degree of mineralization, which in turn depends on a number of factors including age, nutritional adequacy, state of pregnancy and lactation and exposure to weight bearing.
- b. G1a protein — see osteocalcin.
- b. infection — see osteitis, osteomyelitis, osteoarthritis.
- intramembranous b. — bone formed within membrane or under the periosteum.
- jugal b. — see zygomatic bone.
- lamellar b. — mature bone in which the collagen fibers are in an orderly layered arrangement producing lamellae.
- laminar b. — the formation of bone by the periosteum in layers, sometimes more than one layer at a time, to supplement the diaphyseal expansion of the bone. Is marked in farm animals and large dogs, and serves to accommodate the skeleton to the very rapid growth of the musculature.
- lingual b. — see hyoid bone.
- long b. — one whose length usually exceeds its breadth and thickness and which usually bears epiphyses at each extremity during growth.
Structure of typical long bone. By permission from Aspinall V, O'Reilly M, Introduction to Veterinary Anatomy and Physiology, Butterworth Heinemann, 2004 - malar b. — see zygomatic bone.
- marble b's — see osteopetrosis.
- mastoid b. — the posterior part of the petrous temporal bone; the mastoid process.
- b. matrix — the intercellular component of bone. It includes collagen and amorphous ground substance consisting mostly of mucopolysaccharides (chondroitin sulfate).
- b. meal — a product made from meatless bones which are crushed and sterilized. The bones are derived from boning plants and retail outlets. The bonemeal is used as stock feed, fertilizer and in a number of industries. Care is needed in its preparation and in the selection of the bones because of the high risk of transmitting diseases including anthrax, salmonellosis, tuberculosis. A coarse grade of bone flour (see above). Prohibited from being used as a feed in many countries as part of programs to control or prevent bovine spongiform encephalopathy.
- membrane b. — bone that develops within a connective tissue membrane.
- metaplastic b. — bone formed by connective tissue by redifferentiation of mesenchymal cells.
- b. mineral — principally calcium and phosphorus but includes also magnesium and, to a lesser extent, potassium and fluorine. Consisting mainly of hydrated calcium phosphate (apatite) and calcium carbonate.
- b. modeling — the sum of the activities of the endosteum and periosteum of bone to produce bone forms.
- b. neoplasm — includes fibroma, fibrosarcoma, chondroma, osteochondroma, chondrosarcoma, osteoma, osteosarcoma.
- pelvic b. — hip bone.
- perilacunar b. — low density bone around the lacunae of bone which contains much amorphous mineral. In this form the mineral is labile and therefore important in the maintenance of calcium homeostasis.
- periosteal b. — bone deposition by the periosteum in successive laminae; the bone formation in new bone and in a callus, beginning as fibrocellular tissue forming from the endosteum and periosteum, followed by calcification and bone formation.
- b. pinning — see pinning.
- pneumatic b. — bone that contains air-filled spaces.
- premaxillary b. — see premaxilla.
- pterygoid b. — a small skull bone that articulates with the sphenoid.
- b. remodeling unit — osteoclasts, osteoblasts and their progenitors, the basal metabolic unit of bone.
- b. sand — remnants of bone trabeculae destroyed in osteomyelitis and sequestered in pus.
- b. sealant — a composition of beeswax and isopropylpalmitate used to seal the cut end of bone and stop the oozing of blood.
- shin b. — see tibia and cannon bone.
- short b. — one of approximately equal length, width and thickness, usually without epiphyses.
- solid b. — compact bone.
- spongy b. — cancellous bone.
- b. structural unit — see basic multicell unit.
- sutural b's — variable and irregularly shaped bones in the sutures between the bones of the skull.
- b. tumor — includes cartilage-forming tumors (chondroma, osteochondroma, chondrosarcoma, multilobular tumor) and bone-forming tumors (osteoma, osteosarcoma).
- tympanic b. — the part of the temporal bone surrounding the middle ear.
- b. wax — see bone sealant (above).
- wormian b's — sutural bones.
- woven b. — primitive bone with coarse collagen bundles arranged in a disorderly fashion and replaced subsequently by lamellar bone.
