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Articulations. Articulations- points where two or more bones come together to form a joint [ maybe rigid or movable]. Classified by Structure or Function Structure- based on material that joins bones together Fibrous – fibrous connective tissue
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Articulations- points where two or more bones come together to form a joint [ maybe rigid or movable] Classified by Structure or Function • Structure- based on material that joins bones together Fibrous – fibrous connective tissue Cartilagenous – hyaline or fibrocartilage Synovial – joint cavity with synovial membrane
Synovial Joint Capsule is continuous with periosteum Membrane is 2 layers Has blood vessels & nerves
Synovial Fluid • Continuously made, circulated – at any time there is 3 ml [ 0.1 oz] in cavity • Resembles interstitial fluid, but contains proteoglycans secreted by fibroblasts making it thick / viscous • Functions: lubricate joint distribute nutrients and remove waste products shock absorber defense
Accessories of Synovial Joint • Cartilage – fibrocartilage [articular discs or meniscus] • Fat – articular fat pads • Ligaments [ attach bone to bone] • Tendons [ attach muscle to bone] • Bursae – synovial fluid filled ‘pockets’ mini shock absorbers
Function – based on degree of movement • Synarthroses – immovable • Amphiarthroses – slightly movable • Diarthroses – freely moveable
Fibrous Articulations • Bones are held tightly connected by fibrous connective tissue or cartilage. Joints are rigid and immoveable. Sutures – found only in skull. Bones joined by fibrous connective tissue Syndesmosis – band of fibrous connective tissue, holds bones tightly together distal end of tibia/fibula Gomphosis – peg in socket tooth in alveoli- periodontal ligament
Cartilagenous Articulations Hyaline or fibrous cartilage joins bones; limited motion in response to twisting, compression, stress Synchondrosis – hyaline cartilage joins bones. epiphyseal plate, costal cartilages Symphysis – pad of fibrocartilage separates bones. intervertebral discs, symphysis pubis
Synchondrosis Symphysis
Synovial Articulations • Freely moveable joints. Include a capsule lined with a membrane and contains fluid Range of movement limited by: • Structure of bones • Strength and tautness of ligaments, tendons, joint capsule • Size, arrangement, action of muscles
Hinge – concave surface on one articulates with convex surface of another. Pivot – conical surface on one articulates with depression on another Condyloid – oval condyle on one articulates with elliptical cavity on another Gliding- flattened or slightly curved articulating surfaces Saddle – concave and convex surface on each articulating bone Ball and Socket – rounded surface on one articulates with cuplike socket on another Types of Synovial Articulations
Pivot saddle Ball & Socket
Condyloid Gliding Hinge
Bursa – fluid filled sacs near diarthrotic joints – between muscles, skin and bones or tendon and bone. • Reduce friction and stress associated with movement • Tendon Sheaths – modified bursae that surround and lubricate tendons of certain muscles, esp. those that cross wrist and ankle