Transcript JOINTS & Articulations

JOINTS & Articulations
JOINTS & Articulations
Joints occur where 2 bones meet. They
may:
• join two bones with as little
flexibility as possible
• join two bones with a little ' give'
• join two bones with a maximum
flexibility
JOINTS & Articulations
FIBROUS JOINT
• Ends of bones are separated by
fibrous tissue vs. cartilage
• E.g. sutures of the skull (movement
during birthing only), gomphosis
(teeth in maxilla)
JOINTS & Articulations
CARTILAGINOUS JOINT
• cartilage sandwich with bone on
either side
• bone and cartilage fit together
perfectly and the whole thing is cup
shaped
E.g. sternoclavicular joint
JOINTS & Articulations
SYNOVIAL JOINT
• Ends of bones move freely on each
other;
• Sliding surfaces are covered with a
thin layer of articular cartilage
(coefficient of friction <0.002) E.g.
knee joint
Classification of Joints
Complexity
• Simple - 2 articular surfaces (1 male
+ 1 female)
• Compound (elbow joint = humerus &
ulna / humerus & radius / ulna &
radius)
Classification of Joints
Degrees of Movement (freedom)
• Uniaxial - joint which moves substantially
in one plane (like an elbow)
• Biaxial - moves in two planes
• Triaxial - moves in three planes
A ball and socket is multiaxial, but is
equivalent to a triaxial as it has three
degrees of freedom
Classification of Joints
Shape - probably the most widely used
classification
• 1.hinge joints: permit flexion and
extension (knee)
• 2.pivot joints: allow rotation (superior
radio-ulnar)
• 3.gliding or plane joints: have flat
surfaces and allow gliding in several
directions (carpus and tarsus)
Classification of Joints
•
•
•
•
condylar joints: usually regarded as two hinge
joints with separate articulations (TMJ)
saddle joints: have surfaces shaped like two
saddles - allow movement in two planes at right
angles and a little rotation (base of thumb)
ball and socket: allows very free movement
around any axis through ball (hip)
ellipsoid: ball and sockets which are not round;
rotation therefore impossible (radiocarpal joint)
Classification by function
• Movements at two bone ends are
made up of:
1. gliding of one surface over another
- slide
2. angulation of one surface over
another – roll
• 3. rotation about bone axis - spin
Synovial Joints:Related
Structures
Ligaments
• strong connective tissues that run from
bone to bone & help maintain stability in a
joint;
• not elastic & can lose their ability to
perform correctly when over
stretched/torn
• collateral – attach on medial & lateral
aspects of bones to provide support
Synovial Joints:Related
Structures
Fibrocartilage
• occupies the space between certain bones to
form the articular surface;
• can take on many sizes & shapes;
may be round/disk-like (IVD & TMJ) or flat/circular
(meniscus) or exist as a lip or edge to deepen a
joint (GH labrum)
• resilient & functions as a shock absorber
• avascular & relies on synovial fluid for
nourishment; can suffer injury (tears)
Synovial Joints:Related
Structures
Synovial Membrane
• thin tissue surrounding most freely
moving joints;
• membrane secretes synovial fluid
which provides nourishment for
cartilaginous disks, lubrication, and
hydrostatic cushioning
Synovial Joints:Related
Structures
Joint Capsule
• tough fibrous sheet that surrounds
many joints & functions to protect
them and provide stability
Synovial Joints:Related
Structures
Bursae
• liquid-filled membranes that protect
soft tissues as they pass by bony
projections (eg. subacromial bursa of
shoulder)
Synovial Joints:Related
Structures
Fat pads
• literally, small pads of fat tissue to fill in
gaps between bones & cushion bones
Synovial Joints
Synovial Joints-Tibiofemoral
Synovial Joints-Iliofemoral
Synovial Joints-Shoulder Complex
Synovial Joints:InjuriesOsteoarthritis
Synovial Joints:Injuries- GH
Subluxation- Dislocation
Clavicle
Glenoid fossa
Scapula
Humeral
Head
Synovial Joints:Injuries-OUCH
Synovial Joints:Injuries-HELP
Rotator Cuff and Anatomy Pathology