Plate 20 - Joints Flashcards
Joint
Formed when two bones meet or a bone and cartilage meet.
Classified according to structure and amount of movement they permit.
Articulations
Types of Joints
Fibrous
Cartilaginous
Synovial
Fibrous Joints
Fit tightly together
Bound to one another by more or less inextensible connective tissue
Synarthoses – immovable ie. Sutures of skull
Syndesmoses – partly movable ie. Interosseus membrane
Cartilaginous Joints
Cartilaginous, immovable (synchondroses) ie. Growth plates
Fibrocartilaginous, partly movable (amphiarthroses) ie. Intervertebral discs
Synovial
Free moving (diarthroses)
Limbs!!!
Contain a cavity
Features of a Synovial Joint
1) joint (synovial) cavity
2) joint capsule – attached close to articulating end of each bone involved
3) synovial membrane lining inside of capsule EXCEPT articular surface
4) synovial fluid secreted by membrane for lubrication
5) hyaline cartilage covering articulating surfaces
6) ligmaents binding and supporting joint
7) bursae – small synovium lined sacs which help reduce friction
8) fibrocartilage pads (meniscus) to reduce shock and increase surface contact area
Types of Synovial Joint
Gliding Hinge Pivot Ball and Socket Ellipsoid Saddle
Gliding Joint
Flat or curved bones tightly packed
Between carpals and tarsals
Hinge
One plane (uniaxial) Convex bone with within concave bone Ex. Elbow joint
Pivot
Uniaxial
Rounded point of one bone fits into groove of another
Ex. ulnaradial joint
Ex. atlantoaxial joint - NO - dens process of axis provides a type of pivot and collar allowing head and axis to rotate around the dens
Ball and Socket
Triaxial, maximize movement
ex. acetobulofemoral (hip), glenohumeral (shoulder)
Ellipsoid
Biaxial, similar to ball and socket but no axial rotation.
Oval biconvex surface fits into biconvex surface.
Wrist, second metacarpal, 1st phalanx of second finger
Saddle
Biaxial, no axial rotation
Thumb - carpometacarpal joint.
2 concave surfaces
