Joint Notes

1. Joint Notes

2. Definition • functional junction between bones, also known as an articulation. The knee joint

3. Purpose • enable the body to move • bind parts of the skeletal system • permit parts of the skeleton to change shape during childbirth • allow for bone growth

4. Structural Classification 1. Fibrous • Fibrous dense connective tissue joins the bones • very little to no movement (synarthotic) • example: joints of skull (sutures) As you can see on this child’s cranium, the frontal bone is divided into two pieces though the suturafrontalis has began to close.

5. 2. Cartilaginous • disks of fibrocartilage or hyaline cartilage connect the bone • allow limited movement (amphiarthrotic) • example: intervertebral disks There are a total of 23 intervertebraldiscs in the spine. Together they account for approximately 25% of the total height of the vertebral column (this decreases with age as disc height is lost). Click on the picture to learn about herniated discs.

6. 3. Synovial • more complex - ends of bone covered with hyaline cartilage - held together by a capsule of dense connective tissue - filled with synovial fluid that lubricates the joints - some have menisci (shock absorbing pads) • free moving- (diarthrotic)

7. Dislocations Look at the pictures of dislocations shown in this and the next 3 slides. What type of joint is most likely to dislocate? Why?

10. Answer: synovial joints Reason: synovial joints allow the most movement therefore they are more likely to dislocate

11. Use the illustration on the right to find the structures of the knee on the MRI. Click here to watch an ACL Surgery

12. Types of Synovial Joints Look at the picture and decide which type of synovial joint is illustrated. Word Bank Ball and Socket Condyloid Gliding Hinge Pivot Saddle Hinge-allows for extension and flexion, found in the knee and elbow Try It! Swing your knee back and forth in one plane.

13. Word Bank Ball and Socket Condyloid Gliding Hinge Pivot Saddle Ball and Socket- allows for radial movement in almost any direction, found in the hips and shoulders. Try It! Do an arm circle.

14. Word Bank Ball and Socket Condyloid Gliding Hinge Pivot Saddle Gliding joint- bones slide past each other, wrists and ankles are gliding joints Try it: Hole your arm upright and wave side to side.

15. Word Bank Ball and Socket Condyloid Gliding Hinge Pivot Saddle Saddle joint- allows movement back and forth and up and down, but does not allow for rotation- carpal to thumb metacarpal. Try It! 1. Spread all five digits out, then bring them all together side-by-side 2. Cross the thumb over the palm of your hand toward your little finger.

16. Word Bank Ball and Socket Condyloid Gliding Hinge Pivot Saddle Pivot Joint- allows rotation around an axis. The neck and forearms have pivot joints. In the neck the atlas spins over the top of the axis. In the forearms the radius and ulna twist around each other. Try It! 1. Turn your head side to side as if you are saying no. 2. Twist your forearm.

17. Word Bank Ball and Socket Condyloid Gliding Hinge Pivot Saddle Condyloid joint-are similar to a ball and socket joint without the socket. They allow the same type of movement to a lesser magnitude. The wrist is a condyloid joint. Try It! Rotate your wrist.

18. Movement at Joints • Turn to pages 166-167 in your text and study the types of joint movements. • Study the back page of the “Joint Homework”. • Try to act out the action shown. • Complete the worksheet and share your results with the class.