A & P Joint PDF

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joints lecture...

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Joints 10.8.19

Articulation: point of contact between two bones or bones and cartilage, any movement that results in the change of the movement of a bone  Latin o Articulare Functional Classifications amount of movement (closeness determines movability)  Synarthrosis: immovable joint  Amphiarthroses: slightly moveable (ex: pubic symphysis which soften during pregnancy)  Diarthrosis: freely moveable (ex: elbow) Structural Classification  Fibrous: no joint cavity, just pushed together and shows little to no movement o Sutures between skull bones o Syndesmoses two bones are held together by a ligament o Gomphoses peg and socket joint (ex: teeth) held together by fibrous ct  Cartilaginous: still no cavity but bones are held together by cartilage o Synchondroses hyaline cartilage is connector (ex: first rib and sternum) o Symphyses fibrocartilage (ex: intervertebral discs)  Synovial lots of space between bones and joint o Joint cavity o Articular cartilages cushioning and takes irregular surface and makes it smooth, so nothing catches in joint o Articular capsule connective tissue that holds everything together  Fibro capsule outer layer, dense irregular ct  Synovial Membrane inner layer, areolar ct o Synovial fluid lubricates the joint and include phagocytic cells that protect joint by getting rid of decay  Ligaments add stability to joint o Capsular ligament o Extracapsular ligament  Menisci extra wedge of fibrocartilage found in some synovial joints to help cushion (ex: in knees)

Movement  Latin o Movere: to move  Friction Reducers o Bursae sack lined with synovial membrane full of synovial fluid that: cushions and lies between skin and bone, muscle and bone or between ligaments and bone to reduce friction o Tendon sheaths wraps around tendon and envelops it to reduce friction  Factors Limiting Movement o Structural limit  Non-boney parts muscle and skin  Articulating bones cant move because bones wont go any farther in joints o Ligaments  Number more we have, greater the strength but we have but less movement  Tension stretch of ligaments before tearing o Muscle tone muscles are over surface of joints and all muscles stay partially contracted  Types of Movement o Gliding simplest type of movement- one part of bone is sliding back and forth across other o Angular  Flexion decrease angle between two bones  Extension increase angle between two bones, stops at anatomical position  Hyperextension increase past anatomical position  Abduction movement away from the midline  Adduction movement towards the midline  Circumduction the distal end of a bone moves in a circle around the stationary proximal end o Rotation bones moves around its own longitudinal axis  Medial rotation anterior surface is moving towards the midline  Lateral rotation anterior surface is moving away from the midline o Special Movements  Inversion sole of the foot moves inward at the angle  Eversion sole of the foot moves outward at the angle  Protraction clavicle or mandible moves forward  Retraction clavicle or mandible moves backwards  Supination palm upward with the elbows bent  Pronation palm downward with the elbows bent  Elevation upward movement

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 Depression downward movement  Opposition touch our thumb to other fingers Synovial Joints o Gliding (aka plane) o Hinge o Pivot o Condyloid (aka ellipsoidal) o Saddle o Ball-and-socket Joint Disorders o Sprain forceful twisting that causes partial tearing of attachments o Dislocation displacement of bone at joint o Bursitis inflammation of the bursae o Tendinitis inflammation of a tendon sheath almost always from overuse, more common in elderly o Arthritis inflammation of a joint  Osteoarthritis wear and tear of the articular capsule on joint from overuse and age or overweight and generally unilateral  Rheumatoid arthritis is an autoimmune disease and the synovial membrane is attacked by immune system and is almost always bilateral  Gouty arthritis over rich diet in urines causes uric acid to form sodium urate salt that accumulates in soft tissues of a joint most commonly in ball of big toe...