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Flashcards in Joints Deck (23):


sites of union b/n bones or bodies of cartilage

consist of tissues which unite bones & cartilages at these sites


articular surfaces of a joint

surface areas of the apposing structures (generally)


fibrous joints

united by fibrous (connective) tissue

ex. distal tibiofibular joint of leg, joints b/n flat bones of skull (suture joints)


cartilagenous joints

bones are united by cartilage

2 classes: primary & secondary


primary cartilagenous joints (synchondroses)

apposing bones are joined by hyaline cartilage

ex. growth plates of growing long bones, union of first rib w/ manubrium of sternum


secondary cartilagenous joints

articular surfaces of bones covered by thin layers of hyaline cartilage, & hyaline cartilage plates are united by a layer of fibrocartilage

ex. manubriosternal joint, pubic symphysis, intervertebral discs



contains a very high concentration of collagen protein fibers in its matrix

dif type of collagen than that found in matrix of hyaline cartilage


synovial joints

artiuclation in which articular surfaces of bones are separated by a membrane-bound, fluid filled cavity

provide greatest degree of movement b/n bones at expense of stability of joint

degree of movement is inversely proportional to its stability


articular cartilage

thin layer of hyaline cartilage that covers articular surfaces of bones in a synovial joint


synovial membrane

lines fluid-filled cavity between synovial joints, except where the cavity is bored by articular cartilage


synovial fluid

fluid secreted by the highly vascular synovial membrane of a synovial joint

rich in hyaluronic acid

has consistency of thick machine oil

functions as an excellent lubricant b/n bones


fibrous capsule

dense, fibrous connective tissue that encloses an entire synovial joint


articular disc (structure)

piece of fibrocartilage interposed like a shelf or pad b/n articulating surfaces of a synovial joint

around its circumference, anchored to the fibrous capsule of the joint



articular disc of a synovial joint that's incomplete & crescent shaped

ex. knee joint


functions of articular discs & menisci

shock absorption

assistance in providing more even distribution of weight & synovial fluid

improvement of the fit of articular surfaces


plane joints

type of synovial joint

apposed articular surfaces are flat or almost flat & the boens slide on one another

ex. sternoclavicular & acromioclavicular joints


hinge joints

type of synovial joint

resemble the hinge on a door

articular surfaces are molded to each othe rin such a way to allow movement in one plane (uniaxial)

allow flexion & extension

ex. elbow, knee, ankle, & interphalangeal joints


pivot joints

type of synovial joint

movement occurs around one axis (uniaxial)

a central bony pivot is surrounded by a ligamentous ring & rotation is the only movement possible

movement occurs as the pivot turns within the ring, or as the ring turns around the pivot, around the longitudinal axis

ex. atlantoaxial & proximal & distal radioulnar joints


condylar (ellipsoid) joints

type of synovial joint

biaxial joints that allow movement around 2 principla axies which are at right angles to each other

an elliptical convex articular surface fits into an elliptical concave aritcular surface

the movements of flexion-extension, abduction-adduction take place

a combination of these movements allows circumduction around a third axis, but rotation around the third axis is not possible b/c of the ellipsoid shape of the bones

ex. radiocarpal (wrist) & metacarpophalangeal (knuckle) joints


saddle joint

type of synovial joint

biaxial b/c two principal axes of movement

articular surfaces are saddle-shaped

movements include flexion-extension, abduction-adduction, & circumduction (same as condylar)

modest amount of axial rotation is seen as well

ex. carpometacarpal joint of thumb


ball & socket joints

type of synovial joints

ball-shaped head of one bone fits into the socket-like concavity of another

arrangement permits maximum degree of all movement (flexion-extension, abduction-adduction, circumduction, & rotation

greater depth of socket = more stable joint = more limited movement

ex. shoulder & hip joints


3 main factors that determine stability of a joint

shape of articular surfaces (ex. hip)

ligaments (ex. knee)

tone of muscles around the joint (ex. shoulder)


innervation of synovial joints

Hilton's law: the nerve supplying a joint also supplies the muscles that act across the joint & the skin covering the articular insertions of these muscles

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