Joints AKA Articulations

Kinds of joints Synarthroses – no movement Amphiarthroses – slight movement Diarthroses – free movement

synarthroses Fibrous connective tissue grows between the bones No significant movement between bones Ex.sutures

amphiarthroses Cartilage connects the bones Ex. Symphysis pubis, vertebrae Herniated disk – when the disk between the vertebrae is pushed into the spinal canal and pushes on the spinal cord

diarthroses Includes most joints, allows for movement

Types of diarthrotic joints Ball and socket – hip and shoulder, widest range of motion Hinge – movement in 2 directions (flexion and extension), elbow, knee, fingers Pivot – small projection of 1 bone pivots in an arch of another (rotation) atlas/axis Saddle joints – metacarpal bone of thumb and carpal bone, only 1 pair, opposable thumb Gliding – least movable, gliding movements between vertebrae Condyloid – oval projection fits in elliptical socket, wrist

Diarthrotic Joint – the Knee

Diartrotic joint structure Joint capsule – fibrous connective tissue, fits over 2 connecting bones, lined with synovial fluid. Ligament – connect bone to bone, fibrous connective tissue Articular cartilage – layer over ends of bones, protection Synovial membrane – secretes fluid, allows for easier movement, less friction

Joint movements Flexion – reduce angle of joint Extension –increase angle of joint Rotation – spin a bone relative to another Circumduction- moving distal end while keeping proximal end stable Abduction – move away from midline, increase angle of joint Adduction – moving part toward midline, decrease angle of joint