joints Flashcards
what is a joint
physical connection between 2 bones
functions of a joint
allow movement (articulation) provide mechanical support (stability)
what does the functional joint classification refer to
relates to the degree of movement they permit
- synarthrosis, amphiarthrosis, diarthrosis
what is synarthrosis
an immovable joint
what is amphiarthrosis
a slightly movable joint
what is a diarthrosis
a freely movable joint
they have a variety of shapes
permit different types of movement
all are synovial joints
what is the structural joint classification based on
- the presence or absence of a space between the articulating bones
- type of connective tissue that binds the bones together
what is the synovial cavity
space between the articulating bones
types of joints based on the structural classification
fibrous, cartilaginous and synovial joints
what is a fibrous joint
- joint with no synovial joint
- bones are held very closely by fibrous tissue (dense irregular connective tissue) - rich in collagen fibres
- show little to no movement and relatively stable
types of fibrous joints
sutures, gomphosis and syndesmosis
what is a suture
a fibrous joint composed of a continuous thin layer of dense irregular connective tissue (periosteum) - serrated interlocking edges
where do sutures occur
in bones of the skull
classification of suture
functional: synarthrosis (immovable)
structural: fibrous
what is a gomphosis
a peg in socket joint
e.g. roots of teeth in mandible/maxillary bone - supported by fibrous ligaments (periodontal)
classification of gomphosis
functional: synarthrosis (motion is limited)
structural: fibrous
what is a syndesmosis
fibrous tissue bond between long bones which have an interosseous membrane between (ligament)
- forces can pass between these bones
classification of syndesmosis
functional: amphiarthrosis (slightly movable)
structural: fibrous
types of cartilage
elastic, fibrocartilage and hyaline
what is elastic cartilage
formed by elastic fibres, collagen and proteoglycans
it is rigid but had elastic properties
e.g. external ear
what is fibrocartilage and what are its function
it has more collagen than proteoglycans
strongest type of cartilage
it has thicker bundles of collagen fibres
slightly compressible
deals with pressure points (e.g. intervertebral discs)
what is hyaline and what are its functions
cartilage formed by equal amount of collagen and proteoglycans
the collagen fibres are evenly dispersed, are smooth and translucent
provide strong support but are flexible
covers the surface of bones to reduce friction and shock
what is a cartilaginous joint
- joint with no synovial cavity
- bones are held by cartilage - either hyaline or fibrocartilage
- show little or no movement to slight movement
types of cartilaginous joints
synchondroses and symphysis
what is a synchondroses
cartilaginous joint where bones are held together by hyaline cartilage
where are the synchondroses found
found in children and young adults at growing end of long bones
- they are temporary and replaced by bone in adulthood
what do synchondroses allow
allows bone growth but not movement
classification of synchondroses
functional: synarthrosis
structural: cartilaginous
what is a symphysis
type of cartilaginous joint located in midline
includes the intervertebral discs and pubis symphysis
bones in symphysis
the ends of the articulating bones are covered in hyaline
between bones there is a piece of fibrocartilage
classification of symphysis
functional: amphiarthrosis
structural: cartilaginous
what is a synovial joint
joint where the articulating bones are separated by a fluid-filled joint cavity
they are all diarthroses
what is the synovium
sheet of fibrous tissue that secretes synovial fluid
what is the synovial fluid
hyaluronic acid secreted by synovial cells in the synovial membrane and interstitial fluid filtered from blood plasma
what is the function of the synovial fluid
it forms a thin film over the surfaces within the articular capsule
reduces friction by lubricating the joint
absorbs shock
what is a bursa
a small fluid-filled sac or cavity situated in places in tissues where friction would otherwise occur
what are articular discs and menisci
- fibrocartilage pads which lie between the articular surfaces of the bones and are attached to the fibrous capsule
- the discs bind strongly to the inside of the fibrous membrane and usually subdivide the synovial cavity into two spaces, allowing separate movements to occur in each space
which are the movements at the synovial joints
- uniaxial - occurring around 1 axis
- biaxial - occurring around 2 axes at right angles
- multiaxial - occurring around several axes
types of synovial joints
plane, saddle, hinge, pivot, ellipsoid, and ball and socket joints
what is a plane joint
permits sliding/gliding movements
has relatively narrow limits of movement (uniaxial)
e.g. acromioclavicular joint (scapula and clavicle)
what is a saddle joint
synovial joint where the articular surfaces: - have both concave and convex areas - fit together (concave to convex) it allows movement on 2 axes (biaxial) e.g. carpometacarpal joint of the thumb
what is a hinge joint
joint capable of movement in 1 axis only (uniaxial)
the shape of the articular surfaces support and limit the movements
strong ligaments add support
e.g. shoulder and ankle
what is a pivot joint
the joint where a rounded process of bone rotates within a sleeve or ring
movement in 2 axes (biaxial) or multiple axes (multiaxial)
e.g. metacarpophalangeal joint (knuckles)
what is a ball and socket joint
joint where the “ball” is a rounded articular and the “socket” is a concave articular surface
allows movement in almost any direction (mulitaxial)
relatively unstable - dislocation risk
e.g. shoulder and hip
limitations of the synovial joints
- shape and extent of articular surfaces
- tensions of joint capsule
- tensions of ligaments surrounding joint
- muscles crossing and acting upon a joint
- bony parts of joints colliding
what is a ligament
connection between bones
it is tough, flexible
made of fibrous connective tissue
what is a tendon
connects a muscle to a bone
flexible but inelastic cord of strong fibrous collagen tissue
what is osteoarthritis
a degenerative joint disease where articular cartilage and subchondral bone degenerates and the water content of cartilage decreases (reduced proteoglycans)
commonly affects hands, feet, spine and large weight-wearing joints
what are osteophytes
spurs - hard or bony swellings - formed on the joint margins
what are Heberden’s nodes
hard or bony swellings that can develop in the distal interphalangeal joints
what are Bouchard’s nodes
hard or bony swellings that develop in the proximal interphalangeal
what is Rheumatoid arthritis
- chronic inflammatory type of arthritis which consists on the destruction of articular cartilage and ankylosis of the joint
- commonly in hands, feet and cervical spine
- can affect other tissues and organs (lungs - fibrosis; eyes - episcleritis)
what is ankylosis
when the bone locks into the least painful position
what are subcutaneous rheumatoid nodules
firm lumps that appear subcutaneously (ie under the skin) in patients with rheumatoid arthritis
