Synovial Joints

SYNOVIAL JOINTS
Torie Shultz, Noelle Henniger, Chris Scanlon

Synovial Joint
Freely moveable (diarthroic)
Most complex
Consists of:
Articular cartilage
Joint capsule
Synovial membrane which secrets synovial fluid
Ligaments
Bursae
Menisci

Articular Cartilage
Hyaline cartilage covers the bones surface is known as articular cartilage Resists wear and minimizes friction
Subchondral plate- bone beneath articular cartilage that contains elastic cancellous bone
Absorbs shock, protects from stress by body weight and force of contracting muscles
Excessive mechanical stress (obesity or athletics) may cause fractures

Joint Capsule
Tubular joint capsule (articular capsule): two articular cartilage layers that encloses joint cavity
Outer layer: dense connective tissue that attaches to periosteum
Inner layer: shiny, vascular lining of loose connective tissue called synovial membrane Outer fibrous layer of capsule
Encloses joint
Flexible for movement
Strong to prevent pulling apart of articular surfaces

Synovial Membrane
Inner lining layer of loose connective tissue of joint capsule Surrounds closed sac called synovial cavity
Secrets clear, viscous fluid called synovial fluid
Stores adipose tissue and forms moveable pads within joints
Resorbs fluid
Extensions (projections and folds) fill spaces of joint and increase surface area of membrane

Synovial Fluid
Synovial fluid moistens and lubricates smooth cartilage surfaces within joint
Supplies articular cartilage with nutrients obtained from blood vessels Reduces friction between bones Helps with shock absorption Ligaments
Bundles of collagenous fibers called ligaments reinforce joint capsule and bind articular ends of bones
Located in fibrous layer of capsule or accessory structures outside capsule
Surrounds the joint cavity
Prevent excessive movement at joint
Inelastic and tighten when joint stressed

Menisci
Synovial Joints divided into two compartments by disc of fibrocartilage called menisci which is rim of white