skeleton, in anatomy
skeleton, in anatomy, the stiff supportive framework of the body. The two basic types of skeleton found among animals are the exoskeleton and the endoskeleton. The shell of the clam is an exoskeleton composed primarily of calcium carbonate. It provides formidable protection, but it is bulky and severely restrictive of movement. The smallest exoskeletons are found on microscopic animals such as diatoms and certain protozoans. Coral reefs are made up of the accumulated exoskeletons of the coral polyp. The firm, flexible, chitinous (horny) insect skeleton is a combination of protective armor and a framework for attachment of the muscles used in rapid movement. The disadvantage of an exoskeleton is that it is nonliving, and must be shed periodically to allow for growth—a process limiting the maximum size of the organism.The endoskeleton, a framework of living material enclosed within the body, permits larger size coupled with freedom of movement and is characteristic of vertebrate animals. In certain fish, it is made up entirely of cartilage cartilage (kär`təlĭj), flexible semiopaque connective tissue without blood vessels or nerve cells.
..... Click the link for more information. , but in most vertebrates it is a mixture of bone bone, hard tissue that forms the skeleton of the body in vertebrate animals. In the very young, the skeleton is composed largely of cartilage and is therefore pliable, reducing the incidence of bone fracture and breakage in childhood.
..... Click the link for more information. and cartilage. The general arrangement of skeletal parts into skull skull, the skeletal structure of the head, composed of the facial and cranial bones. The skull houses and protects the brain and most of the chief sense organs; i.e., the eyes, ears, nose, and tongue.
..... Click the link for more information. , spinal column spinal column, bony column forming the main structural support of the skeleton of humans and other vertebrates, also known as the vertebral column or backbone. It consists of segments known as vertebrae linked by intervertebral disks and held together by ligaments.
..... Click the link for more information. , ribs rib, one of the slender, elongated, curved bones that compose the chest cage in higher vertebrates. Ribs occur in pairs, and are found in most vertebrates; however, in some lower vertebrates, including fishes, they run along the entire length of the backbone.
..... Click the link for more information. , and appendages is the same in all vertebrates. In addition to its supportive function, the skeleton provides sites for the attachment of the muscles used in movement and shields vital organs such as the brain and lungs. The skeleton of birds is especially adapted for flight; the bones are modified into light, hollow tubes penetrated by air sacs.
The human skeleton consists of 206 bones held together by flexible tissue consisting of cartilage and ligaments ligament (lĭg`əmənt)
..... Click the link for more information. . It is composed of two basic parts, the axial and the appendicular skeletons. The axial skeleton includes the cranium, jawbone, ribs, sternum, and spinal column. The appendicular skeleton is made up of the upper (shoulder or pectoral) and lower (pelvic) girdles (see pelvis pelvis, bony, basin-shaped structure that supports the organs of the lower abdomen. It receives the weight of the upper body and distributes it to the legs; it also forms the base for numerous muscle attachments.
..... Click the link for more information. ) and the bones of the arms and legs. Many diseases associated with the skeleton occur at the joints, notably the various types of arthritis arthritis, painful inflammation of a joint or joints of the body, usually producing heat and redness. There are many kinds of arthritis. In its various forms, arthritis disables more people than any other chronic disorder.
..... Click the link for more information. , although such diseases as bone cancer may directly affect the skeleton. Skeletal remains are vital to physical anthropologists, who use them to trace human evolution.
Bibliography
See P. Shipman, A. Walker, and D. Bichell, The Human Skeleton (1985).
skeleton, in winter sports
skeleton, in winter sports, a type of small, very low, steel-frame sled sled, vehicle that moves by sliding. A sledge is typically a heavier, load-carrying sled drawn by a horse or dog, while a sleigh is a partially enclosed horse-drawn vehicle with runners that has seats for passengers...... Click the link for more information. on which one person, lying face down, slides headfirst down snowy hillsides or down steeply banked, curving, iced chutes similar to those used in luge luge (l
..... Click the link for more information. and bobsledding bobsledding, winter sport in which a bobsled—a partially enclosed vehicle with steerable sledlike runners, accommodating two or four persons—hurtles down a course of iced, steeply banked, twisting inclines.
..... Click the link for more information. . Steering is accomplished by shifting weight or dragging the feet. Originally called tobogganing, skeleton was invented in St. Moritz, Switzerland, in the late 19th cent. It was an event in the Winter Olympic Games in 1928 and 1948, when the games were held in St. Moritz, and again in 2002.
skeleton
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skeleton
skeleton [′skel·ət·ən]
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