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ARTICULATIONS. WHAT IS A JOINT?. A site where two or more bones meet. Provides mobility Weakest point of skeleton. Joint Structure. Fibrous connective membranes Sutures – connected by short fibers from the periosteum (becomes synostosis in adult)
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WHAT IS A JOINT? A site where two or more bones meet. Provides mobility Weakest point of skeleton
Joint Structure • Fibrous connective membranes • Sutures – connected by short fibers from the periosteum (becomes synostosis in adult) • Syndesmoses – connected by ligaments (distal end of tibia & fibula) • Gomphoses -- “peg in sockets” (tooth sockets)
Joint Structure • Cartilaginous - hyaline cartilage holding joint together • Synchondroses– cartilage unites bones (epiphyseal plates & costal joints) • Symphyses – connected by fibrocartilage (pubic symphysis, vertebral joints)
Joint Structure • Synovial joints – separated by a fluid containing joint cavity • Diarthroses - freely moveable joints such as shoulder, knee, hip, and most others
Joints classified by function • Synarthroses • NO MOVEMENT • (sutures, gomphoses, synchondroses, some syndesmoses) • Amphiarthroses – • SLIGHT MOVEMENT • (symphyses, some syndesmoses
Joints by function • Diarthroses - FREELY MOVABLE • Plane (gliding) - tarsals and carpals • Condyloid (ellipsoid) – metacarpophalangeal joints • Pivot - Atlas/Axis; Radius/Capitulum • Saddle - Thumbs • Hinge – Elbow, Knee • Ball and socket – Shoulders, Hips
Structure of Diarthrotic Joint • Two or more opposing bones • Joint capsule of connective tissue surrounds joint cavity • Joint cavity lined with synovial membrane • Articular cartilage – covers ends of bone • Menisci (articular disks) - cartilage pads (knee) • Bursae – flattened sacs filled with synovial fluid • Ligaments – attach bone to bone • Tendons – attach muscle to bone
Types of Movement • Flexion/Extension • Abduction/Adduction • Circumduction • Rotation • Protraction/Retraction
Types of Movement • Elevation/Depression • Inversion/Eversion • Pronation/Supination • Dorsiflexion/Plantar flexion
Joint Injuries • Sprains - ligaments stretched or torn • Cartilage Injuries - torn cartilage rarely repairs because it’s avascular) • Dislocations (luxation) - bones moved out of alignment
Inflammatory/Degenerative Conditions • Bursitis - inflammation of a bursa caused by blow or friction • Tendonitis - inflammation of tendons caused by overuse • Arthritis
Arthritis • >100 different types; affecting 1 out of 7 • Osteoarthritis - Wear & Tear; affects 85% • Rheumatoid Arthritis - Autoimmune • May occur at any age; Most common around 40-50; Affects 1-2% of Americans • Immune cells attack joint tissue causing scarring & ossification • Ankylosis = stiff deformed joints • Gouty Arthritis (Gout) • Caused by build up of Uric Acid
Other Bone Disorders • Rickets - soft bones; lack of calcium due to vitamin D deficiency • Osteoporosis - excessive bone loss • Paget’s disease - excessive bone formation • Osteomyelitis - Inflammation caused by pus-forming bacteria • Achondroplasia - defective endochondral bone growth; form of dwarfism
Osteosarcoma - form of bone cancer • Scoliosis - abnormal lateral curvature of the spine • Kyphosis - abnormal thoracic curvature • Lordosis - abnormal lumbar curvature • Herniated Disk (Ruptured or Slipped Disk) - compression on intervertebral disk presses on nerves