Joints

Joints  Joints = articulations  Hold bones together  Provide motility *all bones except the hyoid bone form a joint with other bones

Classification of Joints  Functional = how much movement allowed  Structural = type of substance in the joint

Fibrous Joints - Immoveable  Bones united by fibrous tissue  Examples  Cranial Sutures  Teeth in sockets Figure 5.27d, e

Cartilaginous Joints - Slightly Moveable  Bones connected by cartilage  Examples  Pubic symphysis  Intervertebral joints Figure 5.27b, c

Synovial Joints - Moveable  Articulating bones are separated by a joint cavity  Synovial fluid is found in the joint cavity

Types of Synovial Joints Based on Shape

Features of Synovial Joints (Protection)  Articular cartilage (hyaline cartilage) covers the ends of bones  Joint surfaces are enclosed by a fibrous articular capsule  Have a joint cavity filled with synovial fluid  Ligaments reinforce the joint

Structures Associated with the Synovial Joint (Protection)  Bursae – flattened fibrous sacs  Lined with synovial membranes  Filled with synovial fluid  Not actually part of the joint  Tendon sheath  Elongated bursa that wraps around a tendon

Synovial Joint - Diagram - 1

Synovial Joint - Diagram 2

Movements at Synovial Joints  Angular Movements: There is an increase or decrease in the angle between bones  Include: Flexion, Extension, Hyperextension, Abduction, and Adduction

Movements at Synovial Joints  Flexion (bend) - involves a decrease in the angle between the surfaces of articulating bones -Ex: biceps curl, bend neck to look at feet, bend trunk to touch toes, make a fist  Extension (straighten) - involves an increase in the angle between the surfaces of articulating bones -Ex: arms hanging at sides, standing up, looking straight ahead, open a fist - fingers up

Movements at Synovial Joints  Hyperextension - continuation of extension beyond anatomical position -Ex: tilting head all the way back to look at sky

Movements at Synovial Joints  Abduction - movement of bone away from midline of body -Ex: spread fingers out; raise leg out to side; lift arm out at 180 degree angle  Adduction - movement of bone toward midline of body -Ex: hold fingers together, stand with legs straight, arms hanging at sides

Movements at Synovial Joints  Rotation Movements - Movement of a bone around its longitudinal axis; may be medial or lateral  Example: turning head on neck - looking to side, shaking head no

Movements at Synovial Joints  Circumduction - A movement in which the distal end of a bone moves in a circle while the proximal end remains stable  Ex: winding up and pitching a baseball

Movements at Synovial Joints Let's Take a Look!

The End!