Joints
Joints
• A joint is the location at which 2 or more bones make contact
• Joints, also called articulations, have 2 functions:
1. They hold bones together securely2. They give the rigid skeleton mobility• Joints are classified in 2 ways: Functionally and
Structurally
Functionally
• The functional classification focuses on the amount of movement allowed by the joint
• There are:1. Synarthroses: Immovable joints2. Amphiarthroses: Slightly movable joints3. Diarthroses: Freely movable joints• Synarthroses and Amphiarthroses are restricted
mainly to the axial skeleton• Diarthroses predominate in the limbs
Structurally
• Structurally, there are:1. Fibrous joints2. Cartilaginous joints3. Synovial joints• As a general rule, fibrous joints are immovable
and synovial joints are freely movable and most cartilaginous joints are amphiarthrotic
Fibrous Joints
• In fibrous joints, the bones are united by fibrous tissue
e.g. sutures of the skull
Cartilaginous Joints
• In cartilaginous joints, the bone ends are connected by cartilage
• Cartilaginous joints allow more movement between bones than a fibrous joint but less than the highly mobile synovial joint
e.g. intervertebral joints
Synovial Joints• Synovial joints are those in which the
articulating bone ends are separated by a joint cavity containing synovial fluid
• All synovial joints have 4 distinguishing features:
1. Articular cartilage2. Fibrous articular capsule3. Joint cavity4. Reinforcing ligaments
Synovial Joints• Articular cartilage: covers
the ends of the bones forming the joint
• Fibrous articular capsule: The joint surfaces are enclosed by a sleeve or capsule of fibrous connective tissue and the capsule is covered with a smooth synovial membrane
Synovial Joints
• Joint cavity: the articular capsule encloses a cavity, called the joint cavity, which contains lubricating synovial fluid
• Reinforcing ligaments: the fibrous capsule is usually reinforced with ligament (connection between bone to bone)
Inflammatory Disorders• Arthritis: describes over 100 different
inflammatory or degenerative diseases that damage the joints
• Acute forms of arthritis usually result from bacterial invasion and are treated with antibiotic drugs
• Chronic forms of arthritis include: osteoarthritis, rheumatoid arthritis, and gouty arthritis
Osteoarthritis (OA)• The most common form of
arthritis• Also called “wear and tear”
arthritis• Affects the articular
cartilages: over the years, there is a softening , fraying and eventual breaking down of the cartilage
• As the disease progresses, the exposed bone thickens and extra bone tissue, called bone spurs, grows around the margin of the eroded cartilage
Movie
Rheumatoid Arthritis (RA)
• It is an autoimmune disease: a disorder in which the body’s immune system attempts to destroy its own tissue
• Movie
Gouty Arthritis (gout)
• A disease in which uric acid accumulates in the blood and may be deposited as crystal in the soft tissues of joints
• Movie