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

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

Structural Classification 1. Fibrous Fibrous dense connective tissue joins the bones very little to no movement (synarthrotic) example: joints of skull (sutures) As you can see on this child’s cranium, the frontal bone is divided into two pieces. This extra joint makes the skull more flexible during the birth process.

2. Cartilaginous disks of fibrocartilage or hyaline cartilage connect the bone allow limited movement (amphiarthrotic) example: intervertebral disks There are a total of 23 intervertebral discs 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.

- ends of bone covered with hyaline cartilage 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) Study this picture and then label the picture found on the homework sheet.

Dislocations Look at the pictures of dislocations shown in this and the next 3 slides. What type of joint (synarthrotic, amphiarthrotic, or diarthrotic) is most likely to dislocate? Why?

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

Torn ACL Use the illustration on the right to find the structures of the knee on the MRI. Click here to watch an ACL repair. This is not gross or bloody.

Types of Synovial Joints Hinge- bones may only move in one direction, allows for extension and flexion, found in the knee and elbow Try It! Swing your knee back and forth in one plane.

Ball and Socket- allows for radial movement in almost any direction, found in the hips and shoulders. Try It! Do an arm circle.

Gliding joint- nearly flat bones slide past each other, the thoracic cage has many gliding joints for breathing, wrists and ankles are gliding joints Try it: Hold your arm upright and wave side to side.

Saddle joint- allows movement back and forth and up and down, but does not allow for rotation, think of one bone being the saddle and the other bone being the rider- carpal to thumb metacarpal is the only example 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.

Pivot Joint- allows rotation around an axis 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.

Condyloid joint- An oval shape condyle fits into an oval shaped depression. Look at the occipital condyle and facet above. Hint: If there is a condyle, there is a condyloid joint. Try It! Nod yes.

Joint Movement Because of joints, the muscles can move the bones in various directions. These directions are given names. These names will be used throughout the rest of the course so commit them to memory.

Watch this video to learn the joint movements Watch this video to learn the joint movements. Link: Anatomical Terms of Movement Fill out your notes as you watch the video.