Joints Flashcards
what are joints?
where bones come together so articulations allow movements and holds skeleton together
how are joints classified? explain
function - how moveable the joint is; structure- how surfaces are connected
describe three functional classifications
synarthroses- immovable
amphiarthroses- slightly moveable
diarthroses- freely moveable
describe synarthroses with an example
strong union between bones so they are important in protecting organs e.g. skull
describe amphiarthroses with an example
thick fibre cartilaginous discs e.g. vertebral discs
describe diarthroses with an example
wide range of motion e.g. elbow
what are the three types of diarthroses
uniaxial- movement in one plane around single axis; biaxial- two; multiaxial; three
describe three classifications of structure
fibrous joints= immovable ; synovial joints= freely moveable ; cartilaginous = range of motion
what do fibrous joints contain and where would they be found
contain lots of dense connective tissue and no joint cavity; found at connecting bones that don’t require movement
describe structure of fibrous joints
- bone edges serrated and united by layer of fibrous tissue
- periosteum layer is continuous
what are the two types of fibrous joints? give examples
- syndesmoses; bones are connected only by ligaments, united by fibrous tissue or internal interaction membrane e.g. fibula and tibia
- gomphoses; peg- in socket that occurs between a tooth and its alveolar socket as teeth are embedded
what ligament holds the teeth in place
periodontal
describe a cartilaginous joint
joints connected by cartilage so lack joint cavity
what are the two types of cartilaginous joints ?Give examples
- synchondroses - contain hyaline cartilage so bones are united, present at epithelial growth plates, between first rib and manubrium of sternum
- symphyses contain fibrocartilage so is incompressible = shock absorber e.g. found between vertebrae and in pelvis
what is a synovial joint
freely movable joint with a cavity filled with fluid to allow mobility i.e. found in limbs
what covers opposing bones and why?
articular cartilage to protect the ends of bones; allows the bones to move against one another
what is contained within joint cavity? what does it contain?
synovial fluid- very viscous, contains hyaluronic acid secreted by cells in membrane
what is the point of the synovial fluid?
acts as lubricant so reduces friction between cartilage layers
what does the synovial membrane together with fibrous layer compromise
articular capsule; reinforces ligaments, nerves and vessels
where does fibrous joint capsule attach?
away from articular margins; strengthened by ligaments and muscles that cross the joint
what do some synovial joints have?
fatty pads or discs of fibrocartilage separating the articulating surfaces= menisci in knee
how is some movement possible?
gliding/ twisting of one bone against another
what are the seven types of synovial joints
hinge, pivot, ball and socket, ellipsoid, saddle, condyloid
what is a hinge joint? give an example
allows movement in one axis; supported by string collateral ligament e.g. elbow
what is a pivot joint? give an example
allows rotation at one long axis; one bone rotates around another with fibrous ring e.g. radius- ulnar joint
what is pronation and supination?
pronation= base of radius rotates over and around head of ulna
supination= palms face up
what is ball and socket? give an example
ball of one joint fits into socket of another so movement in all axes and at least three planes e.g. hip
what is ellipsoid? give an example
- similar to ball and socket; ligaments/ oval shape prevent rotation so only rotates two axes e.g. radiocarpal
what is a saddle joint? give an example
- similar to ball and socket but limited rotation as both bones have concave and convex surfaces e.g. carpometacarpal joint
what is condyloid? give an example
- modified ball and socket; active movement in two axes and passive in third e.g. wrist
describe closely packed joints
stable joints that are strongly united so little movement; associated with protection and weightbearing
describe less closely packed joints
less stable as allows more range of motion e.g. shoulder
what is joint arthrokinematics
specific movements of joint surfaces
what do complex movements involve
roll, spin and glide; never work in isolation
