ch 9: joints

• places of contact between bones, bones + cartilage or bones/teeth

• classified by structure and function

fibrous joint: held together by dense connective tissue (don’t move)

cartilaginous joint: bones joined by cartilage (slightly move)

synovial joint: bones joined by ligaments with fluid filled joint cavity (move a lot)

synarthroses

• amphiarthroses: fibrous cartilaginous (slightly mobile)

• diarthroses: all synovial joints (freely mobile)

**mobility vs stability are inversely related

common types of fibrous joints

• gomphoses (teeth) - “peg in a joint”

• sutures (skull) - interlocking, irregular edges

• syndesmoses (bound by interosseous membrane)

symphyses (pubic) connects bones

costochondritis: localized chest pain - inflammation of the costochondral joints

synovial joints (diarthroses)

• double layered articular capsule

• fibrous layer

• synovial membrane secretes synovial fluid

• articular cartilage (avascular and takes long time to heal)

ligaments

• dense regular connective tissue: connects bone to bone

  • extrinsic: separate from articular capsule

  • intrinsic: are within the articular capsule

bursae (of the knee joint diagram)

• fibrous, saclike structures containing synovial fluid

• lined internally by synovial membrane

• alleviate friction

planes a joint can move on

• uniaxial (1)

• biaxial (2)

• multiaxial

motions

• gliding (wrist)

• angular

• flexion → lateral flexion

• extension → hyperextension

• abduction

• adduction

• circumduction

• rotation → lateral, medial, pronation, supination

• depression

• elevation

• dorsiflexion

• plantar flexion

• eversion

• inversion

• first class layer

  • fulcrum

  • between resistance and effort

• second class layer

  • resistance between fulcrum and effort

• third class layer

  • effort between resistance and fulcrum