prevent bones from dislocating • Other capsule features include ligaments and articular fat pads
13 Special Features • Synovial Membrane – secretes synovial fluid containing slippery hyaluronic acid – brings nutrients to articular cartilage • Accessory ligaments – extracapsular ligaments • outside joint capsule – intracapsular ligaments • within capsule • Articular discs or menisci – attached around edges to capsule – allow 2 bones of different shape to fit tightly – increase stability of knee - torn cartilage • Bursae = saclike structures between structures – skin/bone or tendon/bone or ligament/bone 14 Sprain versus Strain • Sprain – twisting of joint that stretches or tears ligaments – may damage nearby blood vessels, muscles or tendons – swelling & hemorrhage from blood vessels – ankle is frequently sprained • Strain – generally less serious injury – overstretched or partially torn muscle 15 Bursae and Tendon Sheaths • Bursae – fluid-filled saclike extensions of the joint capsule – reduce friction between moving structures • skin rubs over bone • tendon rubs over bone • Tendon sheaths – tubelike bursae that wrap around tendons at wrist and ankle where many tendons come together in a confined space • Bursitis – chronic inflammation of a bursa 16 TYPES OF MOVEMENT AT SYNOVIAL JOINTS • Gliding • Angular movements – Flexion/extension/hyperextension – Lateral flexion – Abduction/adduction – Circumduction • Rotation • Special movements – Elevation/depression – Protraction/retraction – Inversion/eversion – Dorsiflexion/plantar flexion – Pronation/supination – Opposition
17 Gliding (Linear) Movements • Gliding movements occur when relatively flat bone surfaces move back and forth or side to side with respect to one another • In gliding joints there is no significant alteration of the angle between the bones • Occur at carpal and plantar joints 18 Flexion, Extension & Hyperextension • Flexion - decrease in the angle between articulating bones • Extension - increase in the angle between articulating bones • Hyperextension - continuation of extension beyond the anatomical position 19 Abduction and Adduction • Abduction - movement of a bone away from the midline • Adduction - movement of a bone toward the midline 20 Circumduction • Movement of a distal end of a body part in a circle • Occurs at ball and socket, saddle and condyloid joints
21 Rotation • Bone revolves around its own longitudinal axis – medial rotation is turning of
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