6.8: Key Terms

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6.8: Key Terms

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Glossary Entries

Word(s)	Definition	Image	Caption	Link	Source
articular cartilage	thin layer of cartilage covering an epiphysis; reduces friction and acts as a shock absorber
articulation	where two bone surfaces meet
bone	hard, dense connective tissue that forms the structural elements of the skeleton
canaliculi	(singular = canaliculus) channels within the bone matrix that house one of an osteocyte’s many cytoplasmic extensions that it uses to communicate and receive nutrients
cartilage	semi-rigid connective tissue found on the skeleton in areas where flexibility and smooth surfaces support movement
central canal	longitudinal channel in the center of each osteon; contains blood vessels, nerves, and lymphatic vessels; also known as the Haversian canal
closed reduction	manual manipulation of a broken bone to set it into its natural position without surgery
compact bone	dense osseous tissue that can withstand compressive forces
diaphysis	tubular shaft that runs between the proximal and distal ends of a long bone
diploë	layer of spongy bone, that is sandwiched between two the layers of compact bone found in flat bones
endochondral ossification	process in which bone forms by replacing hyaline cartilage
endosteum	delicate membranous lining of a bone’s medullary cavity
epiphyseal line	completely ossified remnant of the epiphyseal plate
epiphyseal plate	(also, growth plate) sheet of hyaline cartilage in the metaphysis of an immature bone; replaced by bone tissue as the organ grows in length
epiphysis	wide section at each end of a long bone; filled with spongy bone and red marrow
external callus	collar of hyaline cartilage and bone that forms around the outside of a fracture
flat bone	thin and curved bone; serves as a point of attachment for muscles and protects internal organs
fracture	broken bone
fracture hematoma	blood clot that forms at the site of a broken bone
hematopoiesis	production of blood cells, which occurs in the red marrow of the bones
hole	opening or depression in a bone
hypercalcemia	condition characterized by abnormally high levels of calcium
hypocalcemia	condition characterized by abnormally low levels of calcium
internal callus	fibrocartilaginous matrix, in the endosteal region, between the two ends of a broken bone
intramembranous ossification	process by which bone forms directly from mesenchymal tissue
irregular bone	bone of complex shape; protects internal organs from compressive forces
lacunae	(singular = lacuna) spaces in a bone that house an osteocyte
long bone	cylinder-shaped bone that is longer than it is wide; functions as a lever
medullary cavity	hollow region of the diaphysis; filled with yellow marrow
modeling	process, during bone growth, by which bone is resorbed on one surface of a bone and deposited on another
nutrient foramen	small opening in the middle of the external surface of the diaphysis, through which an artery enters the bone to provide nourishment
open reduction	surgical exposure of a bone to reset a fracture
orthopedist	doctor who specializes in diagnosing and treating musculoskeletal disorders and injuries
osseous tissue	bone tissue; a hard, dense connective tissue that forms the structural elements of the skeleton
ossification	(also, osteogenesis) bone formation
ossification center	cluster of osteoblasts found in the early stages of intramembranous ossification
osteoblast	cell responsible for forming new bone
osteoclast	cell responsible for resorbing bone
osteocyte	primary cell in mature bone; responsible for maintaining the matrix
osteogenic cell	undifferentiated cell with high mitotic activity; the only bone cells that divide; they differentiate and develop into osteoblasts
osteoid	uncalcified bone matrix secreted by osteoblasts
osteon	(also, Haversian system) basic structural unit of compact bone; made of concentric layers of calcified matrix
osteoporosis	disease characterized by a decrease in bone mass; occurs when the rate of bone resorption exceeds the rate of bone formation, a common occurrence as the body ages
perforating canal	(also, Volkmann’s canal) channel that branches off from the central canal and houses vessels and nerves that extend to the periosteum and endosteum
perichondrium	membrane that covers cartilage
periosteum	fibrous membrane covering the outer surface of bone and continuous with ligaments
primary ossification center	region, deep in the periosteal collar, where bone development starts during endochondral ossification
projection	bone markings where part of the surface sticks out above the rest of the surface, where tendons and ligaments attach
proliferative zone	region of the epiphyseal plate that makes new chondrocytes to replace those that die at the diaphyseal end of the plate and contributes to longitudinal growth of the epiphyseal plate
red marrow	connective tissue in the interior cavity of a bone where hematopoiesis takes place
remodeling	process by which osteoclasts resorb old or damaged bone at the same time as and on the same surface where osteoblasts form new bone to replace that which is resorbed
reserve zone	region of the epiphyseal plate that anchors the plate to the osseous tissue of the epiphysis
secondary ossification center	region of bone development in the epiphyses
sesamoid bone	small, round bone embedded in a tendon; protects the tendon from compressive forces
short bone	cube-shaped bone that is approximately equal in length, width, and thickness; provides limited motion
skeletal system	organ system composed of bones and cartilage that provides for movement, support, and protection
spongy bone	(also, cancellous bone) trabeculated osseous tissue that supports shifts in weight distribution
trabeculae	(singular = trabecula) spikes or sections of the lattice-like matrix in spongy bone
yellow marrow	connective tissue in the interior cavity of a bone where fat is stored
zone of calcified matrix	region of the epiphyseal plate closest to the diaphyseal end; functions to connect the epiphyseal plate to the diaphysis
zone of maturation and hypertrophy	region of the epiphyseal plate where chondrocytes from the proliferative zone grow and mature and contribute to the longitudinal growth of the epiphyseal plate

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