5: Articulations Flashcards
joints
known as articulations, are where two bones meet
classified according to structure or function
structural classification = fibrous, cartilaginous or synovial
fibrous and cartilaginous reflect the type of connective tissue - these joints permit no movement or only slight movements
synovial joints permit free movement
functional classification based on range of movement:
synarthrosis = immovable
amphiarthrosis = slightly moveable
diarthrosis = freely moveable
fibrous joints
suture = synarthrosis, fibrous connections plus interlocked surfaces e.g. skull bones
gomphosis = synarthrosis, fibrous connections plus insertion in bony socket e.g. teeth
syndesmosis = amphiarthrosis, ligament connections e.g. between tibia and fibula
cartilaginous joints
synchondrosis = synarthrosis, cartilage bridge e.g. between first pair of ribs and sternum
symphysis = amphiarthrosis, connection by fibrocartilage pad e.g. between vertebrae
synovial joints
diarthrosis - wide range of motion
complex joint bound by joint capsule, lined by synovial membrane
contains synovial fluid to lubricate and reduce friction
end of bones covered with articular cartilage
menisci in knee = fibrocartilage pad for shock absorbing
fat pads protect articular cartilage
bursa is small packets of connective tissue containing synovial fluid - reduce friction and absorb shock
plane movement
two opposing surfaces glide past each other in one plane
e.g. articulating carpal or tarsal bones
movement slight but can take place in any direction
joint capsule and ligaments prevent rotation
angular movement
flexion = angle decreases
extension = angle increases
hyperextension = extension past anatomical position
abduction = movement away from midline of body
adduction = movement towards midline of body
circumduction = conical circular movement
rotation
rotation involves turning around the longitudinal axis of the body or limb
pronation = rotation of wrist and hand to palm facing forward to palm facing back
supination = opposite ^
special movements
inversion = twisting motion of foot turning the sole inwards
eversion = turning sole outwards
dorsiflexion = flexion at ankle so toes point up
plantar flexion = extension of ankle so toes point down
opposition = movement of thumb toward palm
reposition = return thumb from opposition
protraction = move part of body anteriorly in horizontal plane
retraction = reverse of protraction
elevation and depression = move a structure in superior or inferior direction e.g. jaw
lateral flexion = bending vertebral column to side
types of synovial joints
gliding (plane) = flattened or slightly curved surfaces that slide across each other, slight movement, multidirectional movement in a single plane
hinge = angular motion in a single plane
condylar = oval articular face nestled within a depression, angular movement in two plane
saddle = articular faces that fit together like rider and saddle, concave and convex faces, angular movement in two places and circumduction
pivot = permits rotation
ball and socket = round head sits in cup shaped depression, angular movement, rotation, circumduction
factors affecting movement
joint and accessory structures e.g. shape, capsule, ligaments, menisci
tendons and muscles crossing over the joint
more a joint can move, the less stable it is
intervertebral joints
articular processes of vertebrae articulate via gliding joints
bodies of vertebrae articulate via symphyseal joints
except for first cervical vertebrae, the vertebrae are separated and cushioned by pads called intervertebral discs
each disc has a tough outer layer of fibrocartilage, and a soft elastic core
shoulder (glenohumeral) joint
joint with greatest range of motion, most frequently dislocated
ball and socket
head of humerus articulates with glenoid cavity of scapula
ring of fibrocartilage called glenoid labrum deepens cavity of scapula
relatively loose joint capsule extends from scapular neck to humerus
bursae are relatively large to reduce friction where large muscles and tendons pass across
rotator cuff = group of muscles on surface of joint capsule that swing the arm
elbow joint
two articulations - between humerus and ulna (trochlear with trochlear notch) and between humerus and radius (capitulum with head of radius)
ulna and humerus strongest
stability because the bony surfaces of the humerus and ulna interlock, joint capsule is thick and capsule reinforced by strong ligaments
hip joint
ball and socket diarthrosis
head of femur articulates with acetabulum (deep socket)
fibrocartilage pad called acetabular labrum, fat pad called acetabular fossa and ligaments to resist compression, absorb shock and distort without damage
joint capsule dense and strong
extremely stable
knee joint
three articulations
two between femur and tibia (medial condyle to medial condyle and lateral condyle to lateral condyle)
and one between patella and femur
pair of fibro cartilage pads (the medial and lateral menisci) lies between femoral and tibial surfaces - cushion and conform shape of surfaces
fat pads for padding
bursae reduces friction
ligaments - patellar ligament, anterior and posterior cruciate, tibial and fibular collateral ligaments
