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Joints. Joints. A joint is the location at which 2 or more bones make contact Joints, also called articulations, have 2 functions: They hold bones together securely They give the rigid skeleton mobility Joints are classified in 2 ways: Functionally and Structurally. Functionally.
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Joints • A joint is the location at which 2 or more bones make contact • Joints, also called articulations, have 2 functions: • They hold bones together securely • 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: • Synarthroses: Immovable joints • Amphiarthroses: Slightly movable joints • Diarthroses: Freely movable joints • Synarthroses and Amphiarthroses are restricted mainly to the axial skeleton • Diarthroses predominate in the limbs
Structurally • Structurally, there are: • Fibrous joints • Cartilaginous joints • 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: • Articular cartilage • Fibrous articular capsule • Joint cavity • 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
Rheumatoid Arthritis (RA) • It is an autoimmune disease: a disorder in which the body’s immune system attempts to destroy its own tissue
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