Chapter 2 - the joints Flashcards
joint
junction or pivot point between two or more bones
Fibrous joint
Synarthrosis
- junction between bones held together by dense irregular connective tissue
- little or no movement(sutures, teeth, distal tibiofibular joint, interosseous membrane)
- allows for dispersion of forces
cartilaginous joint
synarthrosis
- junction between bones formed primarily by fibrocartilage and/or hyaline cartilage
- allows restrained movements to transmit and disperse forces between bones(shock absorption)
- ex: intervertebral disc, manubriosternal joint, pubic symphysis
Diarthrosis
synovial joints
- specialized for movement
- Always contain:
1) synovial fluid
2) articular cartilage
3) articular capsule
4) synovial membrane
5) capsular ligaments
6) blood vessels within capsule
7) sensory nerves within capsule
intraarticular discs
Diarthrosis
- menisci
- pads of fibrocartilage which increase articular congruency and improve force dispersion
- for stability and fit
labrum
diarthrosis
- fibrocartilage which forms a bony rim to thicken and support attachments for the joint capsule
- deepens the concave member of the joint
- ex: hip and shoulder
fat pads
diarthrosis
- thickens the joint capsule and fills spaces formed by incongruent bony surfaces
- between fibrous capsule and synovial membrane
- prominent in elbow and knee
synovial plicae
diarthrosis
- folds of slack inner layers of joint capsule which increase synovial surface area and reduce tension on synovial lining
- redundant folds in bursa for stretching purposes
Hinge joint
primary angular movements of flexion/extension
- ex: humeroulnar joint, interphalangeal joints of digits
pivot joint
mobile member of the joint is oriented parallel to the axis of rotation
- spinning of one member around a single axis of rotation
- ex: proximal humeroradial joint, atlantoaxial joint
ellipsoid joint
one convex elongated surface mated with an elongated concave surface
- severely restricts spin unless joint dislocates
- allows biplanar motions, usually flexion/extension, abduction/adduction
- ex: radiocarpal joint
ball-and-socket joint
a spherical convex surface paired with a cuplike socket
- motion in 3 planes
- angular motions = flex/ext, abd/add, internal/external rotation
- ex: glenohumeral joint, coxafemoral joint
plane joint
a pairing of 2 flat or relatively flat surfaces
- allows for slide or combined slide and rotation
- ex: intercarpal joints, intertarsal joints
saddle joint
2 surfaces: 1 concave and 1 convex surface on each bone
- allows biplanar motion
- spin is limited
- ex: carpometacarpal joint of the thumb, sternoclavicular joint
condyloid joint
similar to ball-and-socket, but concave member is very shallow
- usually allows 2 degrees of freedom
- angular motions = either flex/ext and abd/add or flex/ext and axial rotation
- ex: metacarpophalangeal joint, tibiofemoral joint
axis of rotation
rarely fixed in joints
usually through the convex
instantaneous axis of rotation
the location of the axis of rotation of a joint at a given arc of motion
evolute
the path of the serial locations of the instantaneous axes of rotation
- more accurate with smaller arcs of motion
joint play movement
accessory movement
- normal movement not under voluntary control which occurs in response to an outside force
- are necessary to perform pain-free normal movement
- used by PT for evaluation of joint function
- different from PROM
Component movement
accessory movement
- normal movement not under voluntary control which occurs in accompaniment with active movement
- ex: roll and slide
Classification of joint mobility
0 = ankylosis(no movement) 1 = very restricted 2 = slightly restricted 3 = normal 4 = slightly hypermobile 5 = very hypermobile 6 = unstable(excessive ROM, without restraints of capsule and ligaments)
Type 1 collagen
thick, rugged, stiff and elongate very little
- primary protein in ligaments, fascia, fibrous joint capsules and tendons
type 2 collagen
thinner with less strength than type 1
- provides flexible, woven framework for maintaining shape of hyaline cartilage
elastin fibers
resist tensile, stretching forces but have more “give”
- readily return to original shape after deformation
ground substance
Glycosaminoglycans(GAG’s), H20, solutes
- holds water and provides support
cells within joints
responsible for maintenance and repair
- sparse, which contributes to poor/incomplete healing
avulsion fracture
tendon pulls away from bone and breaks away bone
fibroblasts
disperses forces
- grows according to forces
aging and joints
- slowing of rate of fiber and GAG replacement/repair
- microtrauma accumulated over time may lead to mechanical failure and signs/symptoms
- decrease in H2O-binding capacity(less compressive strength)
- decrease in motion may lead to adhesions/contractures within joints which then limit function
- fractures within joints will heal slower
- osteoporotic bone may fracture more readily due to joint loading
Immobilization on connective tissues within a joint
decrease in the strength of tissues which may not fully recover
- balance the need for immobilization with early movement to prevent change in tissue
acute trauma to joint
- torn/stretched ligaments or joint capsule lead to pain, inflammation, and joint instability
- acute traumatic instability
- may lead to intraarticular fractures
- unhealing areas may lead to premature degeneration
- inner areas of cartilage have poor blood supply
chronic trauma in joints
- “overuse syndrome” = accumulation of unrepaired minor damage over time
- gradual weakening and instability of the joint
- muscle guarding
- recurring instability can lead to abnormal loading patterns
- reduction of the shock absorption ability
OA
osteoarthritis
- gradual erosion of articular cartilage with a low inflammatory component
- fibrous capsule/synovium become distended and thickened
idiopathic OA
absence of specific cause
- affects one or a few joints
familial OA or generalized OA
affects hand
- more frequent in women
post-traumatic OA
any synovial joint exposed to sufficient trauma
rheumatoid arthritis(RA)
systemic, autoimmune connective tissue disorder
- strong inflammatory component(capsule, synovium, synovial fluid)
- destruction of multiple joints
- articular cartilage is exposed to an enzymatic process that erodes the articular surface
- joint instability and pain
