Articulations / Joints

Joints - Articulations Where 2 bones meet. Classified by degree of motion (functional) and major connective tissue types that bind the bones together (structural) Fibrous joints – united by fibrous tissue and has little to no movement. Example – Sutures, gomphosis (teeth), syndesmosis –tibia / fibula distal articulation Cartilaginous joints – united by cartilage. Only slight movement. Synchondrosis – epiphyseal plate, Symphysis - pubic Synovial joint – freely moveable contains synovial fluid in a cavity surrounding bones. Examples – shoulder, knee http://www.botany.uwc.ac.za/sci_ed/grade10/manphys/joints.htm

Function classification Synarthrosis – immovable joint Amphiarthrosis – slightly movable Diarthrosis – freely movable. -sis is replaced with –ses for the plural form

Capsular nature of a synovial joint Cavity (synovial joint) enclosed by a capsule (2 layers) Fibrous cartilage – dense irregular, encloses cavity Ligaments – connects bone to bone Tendons – connect muscles to bone Articular cartilage – hyaline cartilage at ends of bones Synovial membranes –areolar, produced synovial fluid for lubrication, nutrients, and metabolic waste removal

Capsular nature of a synovial joint Articular disc / meniscus – pads of fibrocartilage that lie between the articular surfaces of the bones (lateral and medial) Bursae – closed sacs, with a synovial lining. Subcutaneous (patella), subfascial – between muscles, Subtendinous – tendon and process or tendon

Synovial joint

The knee joint Patellar ligament – patella to tibia, anterior Oblique popliteal ligament - posterior surface Acruate popliteal ligament – lower later post. Medial collateral ligament – medial (inside) Lateral collateral ligament – lateral (outside) Anterior cruciate ligament – tibia, post and laterally to the femur, 70% serious injury Posterior cruciate ligament – tibia, anterior and medial to the femur (menisci, bursae)

Knee joint

Synovial joints Joint Description Example Planar Flat or slightly curved Wrist, ankle Hinge convex one concave other elbow, knee Ball and Socket ball one socket other shoulder, hip Saddle 2 saddle at right angles thumb, wrist Pivot Rotation on axis head (no) Condyloid Convex oval projection in a concave oval fossa Metacarpal, phalanges

Major joint movement Flexion – decrease in the angle Extension – increase in the angle Hyperextension – extension beyond position Abduction – away from midline Adduction – toward midline Pronation – palm down Supination – palm up Eversion – foot out Inversion – foot in Dorsiflexion – foot up Plantar flexion – foot down http://www.meddean.luc.edu/lumen/MedEd/GrossAnatomy/ue/ueaction.html

Major joint movement con’t Rotation – turn around long bone axis Protraction – structure glides to anterior (front) Retraction – structure glides to posterior (back) Elevation – move structure superior (up) Depression – move structure inferior (down) Excursion – move one side to another Opposition – move of thumb to pinky Reposition – return thumb / pinky to normal Circumduction – arm / hip circles

Aging and joints Decreased synovial fluid Articular cartilage thins (glucosamine chondroitin / shark cartilage) Ligaments shorten and lose flexibility Degenerative changes in vertebral column, hunched – over posture Stretching and aerobic exercise that help with range of motion, help to minimize aging effects

Joint Disorders Bursitis – inflammation of bursa (elbow and shoulder) Arthritis – inflammation of the whole joint Rheumatoid arthritis – connective tissue disorder (excess growth) with severe inflammation of small joints Rheumatic fever – bacterial (strep) infection that causes RA if left undetected. Fibrositis – inflammation of fibrous connective tissue in a joint; “rheumatism,” lumbago – lower back Osteoarthritis – Degenerative joint, elderly, weight – bearing joints

Joint disorders continued Gout – uric acid crystals in joint at large toe base Sprain – twisting tears ligaments (ankles and wrists) Strain – stretched or partially torn muscle Slipped Disk – intervertebral disk protrudes or moves out of place, pressure on nerve Dislocation – temporary displaced bone Cumulative trauma disorder – ongoing “repetitive” or overuse damage to soft tissue. Carpal tunnel- medial nerve as it passes through the carpal tunnel