Post on 12-Jan-2016
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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 planesA 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:Injuries- Osteoarthritis
Synovial Joints:Injuries- GH Subluxation- Dislocation
Humeral Head
Glenoid fossa
Scapula
Clavicle
Synovial Joints:Injuries-OUCH
Synovial Joints:Injuries-HELP