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:Injuries- Osteoarthritis
Synovial Joints:Injuries- GH Subluxation- Dislocation Humeral Head Glenoid fossa Scapula Clavicle
Synovial Joints:Injuries-OUCH
Synovial Joints:Injuries-HELP
Rotator Cuff and Anatomy Pathology