Anatomy- Joints

joints/articulations

site where 2 or more bones meet

what are the two ways joints are classified?

functionally and structurally

functional classification

focuses on the amount of movement the joint allows

structural classification

based on whether fibrous tissue, cartilage, or a joint cavity separates the bony regions at the joint

synarthrosis

immovable joints, axial skeleton

amphiarthrosis

slightly moveable joints, axial skeleton

diarthrosis

freely moveable joints, appendicular skeleton

fibrous joints

immovable, fibrous tissue.

ex. sutures of the skull

sutures of the skull

irregular edges of bone interlock and bound by connective tissues

gomphoses

peg in socket joints found where teeth meet the facial bones

syndesmoses

joint connecting the distal ends of the tibia and fibula, connecting fibers are longer so joint has more give

cartilaginous joints

has 2 varieties (synchondroses and symphyses)

synchondroses

immovable, linked by hyaline cartilage, epiphyseal plate

ex. joints between ribs and sternum

symphyses

slightly moveable, linked by discs of fibrocartilage

ex. intervertebral discs of spinal column and pubic symphysis of pelvis

synovial joints

at bone ends, separated by a joint cavity with synovial fluid, in appendicular skeleton

articular cartilage

hyaline cartilage covers ends of bones forming a joint

articular capsule

joint surfaces are enclosed by a layer of fibrous connective tissue lined with smooth synovial membrane

joint cavity

cavity containing synovial fluid secreted by synovial membrane.

reinforcing ligaments

fibrous layer of capsule reinforced with ligaments

bursae

flattened fibrous sacs lined with synovial membrane with thin film of synovial fluid. common where ligaments, muscle, skin, tendons, or bones rub together

tendon sheath

elongated bursae wrapping completely around a tendon to reduce friction

plane joint

nonaxial, wrist, flat with gliding movements

hinge joint

uniaxial, knee, angular movement, cylinder to trough

pivot joint

uniaxial, between radius and ulna, rounded end fits into sleeve/ring

condylar joint

biaxial, knuckle, side to side and back and forth

saddle joints

biaxial, thumbs, convex and concave areas (saddle for horse)

ball and socket joint

multiaxial, shoulder and hip, rotating, sphere head fits into socket

nonaxial

gliding doesn’t involve rotation at any axis

uniaxial

allows movement around one axis only

biaxial

movement occurs around 2 axes

multiaxial

allows for movement in all axes including rotation

fibrous joints *

• axial skeleton

• united by fibrous tissue

• immovable

• ex. sutures of skull, gomphoses, syndesmoses

cartilaginous joints *

• axial skeleton

• united by cartilage

• synchondroses: immovable, hyaline cartilage

• symphyses: slightly moveable, fibrocartilage

• ex. epiphyseal plate, pubic symphysis

synovial joints *

• appendicular skeleton

• joint cavity with synovial fluid, articular cartilage, ligaments, joint capsule

• freely moveable

• 6 types: plane, hinge, condylar, ball and socket, saddle, pivot