Lecture VI

• Joints are where bones touch or any bony connection
• Joints are less stable and more mobile
• Stability and mobility are based on bony articular surfaces
• Functions of joints include leverage and connection
• Leverage is to move a load around a pivot, the joint is the pivot
• Skeletal muscles causes bone movement
• Connection holds bones together
• Synarthrosis is the most stable
• Synarthrosis has no movement
• Synarthrosis rarely break or get damaged
• Synarthrosis protect delicate internal organs
• Synarthrosis examples include the skull suture, teeth, ribs
• An example of symphysis is the joints between intervertebral and between public symphysis
• Amphiarthroses is the second most stable
• Amphiarthroses can allow for very limited movement
• Amphiarthroses joints generally do not move but can if necessary
• Amphiarthroses are typically located between paired bones
• Diarthroses are the most mobile
• Diarthroses are the most common
• Diarthroses movement is limited by bony contact surfaces
• Fibrous joints are typically connected by layers of dense regular connective
• In dense regular connective, collagen fibers run in one direction
• Fibrous joint use many layers of dense regular connecitve so ot mistaken for irregular dense
• Monoaxial: single plane one pair of opposing motions 


  Example: elbow with back and forth movement
• Biaxial: allows for two planes of movement two sets of opposing motion 


  Example: metacarpal and jaw with side-to-side movement and back and forth movement
• Triaxial: allows for movement in three or more planes, most mobile, allows for circumduction (full circle movement)


  Example: arms and legs
• Nonaxial: bones can only slide against each other
• Bone fractures heal rapidly due to vascularity
• Damage is usually to synovial joint so slower healing is caused by poor vascularity
• Sprain is the overstretch of a joint, ligament or joint capsule that becomes damaged
• Subluxation is the lost part of bone contact, a partial dislocation
• Luxation is the loss of bony contact on surfaces, a full dislocation
• Synovial joints are the most mobile
• Synovial joints are the least stable
• Synovial joints are structurally complex
• Synovial joints require synovial membrane (what's around it)
• Synovial joint require epithelia and areolar connective tissue, as well as synovial fluid
• Epithelia in synovial joints contain synoviocytes which create and secrete synovial fluid
• Areolar connective tissue in synovial joints is responsible for cushioning and vascularity
• Synovial fluid in synovial joints is responsible for cushioning, carrying nutrients and wastes, and lubricating the surface of the bone