cartilage

[Middle English, from Old French, from Latin cartilāgō, cartilāgin-.]

For more information on cartilage, visit Britannica.com.

A firm, resilient connective tissue of vertebrates and some invertebrates. Isolated pieces act to provide support and anchor muscles, or with bone to contribute its resilience and interstitial growth to skeletal functions. Cartilage comprises a firm extracellular matrix synthesized by large, ovoid cells (chondrocytes) located in holes called lacunae. The matrix elements are water bound by the high negative charge of extended proteoglycan (protein-polysaccharide) molecules, and a network of fine collagen fibrils. The elements furnish mechanical stability, give, and tensile strength, but allow the diffusion of nutrients and waste to keep the cells alive. See also Bone; Collagen.

Cartilage is modified in several ways. In elastic cartilage, elastic fibers in the matrix increase resilience, as in cartilages supporting the Eustachian tube, mammalian external ear, and parts of the larynx. Where cartilage joins bones tightly at certain joints with limited mobility, for example, at the pubic symphysis and between vertebrae, the matrix of fibrocartilage contains prominent collagen fibers and has less proteoglycan than the typical hyaline variety. Hyaline cartilage, named for its glassy translucence, is the major support in the airway; and throughout the embryo, pieces of it develop as a precursor to the bony skeleton, except in the face and upper skull. See also Ear (vertebrate); Larynx.

The primitive cartilaginous skeleton undergoes another modification, by locally calcifying its matrix. At sites of calcification, invading cells destroy the cartilage and mostly replace it by bone, leaving permanent hyaline cartilage only at the joint or articular surfaces, in some ribs, and, until maturity, at growth plates set back from the joints and perpendicular to the long axis of limb bones. The precarious physiological balance between chondrocytes and matrix materials in the heavily loaded articular cartilage breaks down in old age or in inflamed joints. See also Arthritis; Connective tissue; Joint (anatomy); Skeletal system.

Cartilage is a tough, resilient material, found in various sites but especially important in large weight-bearing joints as it lines the articulating bone ends. Due to its thickness and elasticity it is thought to act as a ‘shock-absorber’, cushioning the impact of movement. In the knee there is an extra layer of cartilage separating the bone ends (meniscus), presumably because of the amount of mechanical stress this joint is subjected to. These can be torn by rotational injuries, particularly in football and rugby players, a condition commonly referred to as ‘torn cartilage’. It is sometimes possible to repair the meniscus by ‘key-hole surgery’ (arthroscopy) which avoids having to open the joint; if the damage is too great then the meniscus is removed (menisectomy), usually by arthroscopy. Wear and thinning of articular cartilage in the knee and hip is associated with the development of osteoarthritis. Unlike most tissues in the body, cartilage has no blood vessels within it (it is ‘avascular’) and relies on getting its nutrients, essential for the continued well-being of the cells within the cartilage matrix (chondrocytes), from the thin film of fluid lining the joint cavity (synovial fluid). This fluid is derived from the blood supplying the joint capsule, and its rapid turnover is important for keeping the chondrocytes supplied with oxygen and other essential substances. Cartilage is also found near the ends of long bones (epiphysis) in children, where it plays an important role in longitudinal bone growth after birth. New chondrocytes are generated, thickening the epiphysis producing lengthwise growth, whilst the cartilage matrix ‘left behind’ acquires mineral deposits and forms bone. Cartilage is also found in other sites such as the nose, ears, and larynx (externally visible as the ‘Adam's apple’ in males), where it provides lightweight support or flexibility.

— William R. Ferrell

See also bone; connective tissue; joints.

The hard connective tissue of the body, composed mainly of collagen, together with chondromucoid (a protein combined with chondroitin sulphate) and chondroalbuminoid (a protein similar to elastin). New bone growth consists of cartilage on which calcium salts are deposited as it develops.

A derivative of connective tissue arising from the mesenchyme. Typical hyaline cartilage is a flexible, rather elastic material with a semitransparent, glasslike appearance. Its ground substance, or matrix, is a complex protein (chondromucoid) through which is distributed a large network of connective tissue fibers. Distributed throughout the matrix are cartilage cells that are rounded and do not have the branching characteristics of bone cells. The cells are isolated in the matrix they have secreted and normally have no blood vessels. Therefore nutrients and metabolites are exchanged with the circulation by passage through the matrix.

Tough and flexible connective tissue that forms the skeleton of an embryo and most of the skeleton of infants. As a child grows, much of the cartilage is converted to bone. Cartilage is characterized by rounded cartilage cells (called chondrocytes) surrounded by mucopolysaccharide matrix (chondrin), which is rich in collagen. Cartilage has no nerves or blood vessels and heals slowly when damaged. There are three main types: hyaline cartilage, fibrocartilage, and white fibrocartilage. The pieces of semi-lunar cartilage found in the knee are called menisci.

A kind of tough but elastic connective tissue that can withstand considerable pressure. It makes up portions of the skeletal system, such as the linings of the joints, where it cushions against shock. Cartilage is also found in other body structures, such as the nose and external ear.

A specialized, gristly connective tissue present in both mature animals and embryos, providing a model in which most of the bones develop, and constituting an important part of the organism's growth mechanism; the three most important types are hyaline cartilage, elastic cartilage and fibrocartilage. Also, a general term for a mass of such tissue in a particular site in the body.

• alar c's — the cartilages of the wings of the nose.
• annular ear c. — a ring of cartilage interposed between the rolled-up auricular cartilage and the skull.
• arthrodial c., articular c. — that clothing the articular surfaces of synovial joints.
• arytenoid c's — two pyramid-shaped cartilages of the larynx.
• auricular c. — cartilage of the pinna and much of the external ear canal.
• c. canals — tunnels containing blood vessels incorporated in developing cartilage.
• connecting c. — that connecting the surfaces of an immovable joint.
• costal c. — a bar of hyaline cartilage that attaches a rib to the sternum in the case of true ribs, or to the immediately cranial rib in the case of the anterior false ribs.
• cricoid c. — a ringlike cartilage forming the caudal part of the larynx.
• diarthrodial c. — articular cartilage.
• distal phalangeal c. — the ungual cartilages of the third phalanx in the horse lie mostly against the hoof wall but can be palpated if ossified. See also sidebone.
• elastic c. — cartilage that is more opaque, flexible and elastic than hyaline cartilage, and is further distinguished by its yellow color. The ground substance is penetrated in all directions by frequently branching fibers that give all of the reactions for elastin.
• c. emboli — see fibrocartilaginous embolic myelopathy.
• ensiform c. — xiphoid process.
• fibrous c. — fibrocartilage.
• floating c. — a detached portion of semilunar cartilage in the stifle joint.
• hoof c. — see distal phalangeal cartilage (above).
• hyaline c. — flexible, somewhat elastic, semitransparent cartilage with an opalescent bluish tint, composed of a basophilic fibril-containing substance with cavities in which the chondrocytes occur.
• interarytenoid c. — an occasional cartilage located between the two arytenoid cartilages.
• nasal c. — rostral end to the internasal septum, separating the nasal cavities and anchoring the other cartilages around the nostrils.
• parapatellar c. — cartilaginous plates medial and lateral to the patella in some species, e.g. dogs.
• permanent c. — cartilage that does not normally become ossified.
• retained enchondral c. cores — occur in ulnar metaphysis and lateral femoral condyles of young, giant breed dogs. Visible radiographically as radiolucent inverted cones, extending into the metaphysis, they are often associated with growth deformities such as forelimb valgus and genu valgum.
• reticular c. — elastic cartilage.
• scapular c. — dorsal extension of the scapula in ungulates; tends to calcify with age.
• c. scissors — used for ear cropping in dogs.
• semilunar c. — one of the two intra-articular cartilages of the stifle joint.
• temporary c. — cartilage that is normally destined to be replaced by bone.
• thyroid c. — the unpaired cartilage of the larynx to which the vocal folds attach.
• tibial c. — the bed of cartilage located on the caudal surface of the intertarsal joint of birds; the tendons of the digital flexors pass through it.
• ungual c. — see distal phalangeal cartilage (above).
• vomeronasal c. — either of the two narrow strips of cartilage, one on each side, of the nasal septum supporting the vomeronasal organ.
• xiphoid c. — posterior continuation of the sternum; supports the anterior abdominal wall, especially the linea alba.
• yellow c. — elastic cartilage.

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

Common misspelling(s) of cartilage

• cartilege
• cartilidge

Dansk (Danish)
n. - brusk

Nederlands (Dutch)
kraakbeen

Français (French)
n. - cartilage

Deutsch (German)
n. - Knorpel

Ελληνική (Greek)
n. - (ανατ.) χόνδρος, (μαγειρ.) τραγανό

Italiano (Italian)
cartilagine

Português (Portuguese)
n. - cartilagem (f)

Русский (Russian)
хрящ

Español (Spanish)
n. - cartílago

Svenska (Swedish)
n. - brosk

中文（简体）(Chinese (Simplified))
软骨

中文（繁體）(Chinese (Traditional))
n. - 軟骨

한국어 (Korean)
n. - 연골

日本語 (Japanese)
n. - 軟骨

العربيه (Arabic)
‏(الاسم) غضروف‏

עברית (Hebrew)
n. - ‮סחוס, חסחוס‬

If you are unable to view some languages clearly, click here.

To select your translation preferences click here.