Joints

Major Joint Classifications u Synarthrodial u Amphiarthrodial –Cartilage –Ligament u Diarthrodial

Diarthrodial Joints u Characteristics –Joint Capsule

Diarthrodial Joint Types u Gliding u Hinge u Pivot u Condyloid u Saddle u Ball and Socket

Range of Motion of Joint Type u Anatomical Compromises –some sacrifice mobility for stability –some sacrifice stability for mobility »Flexibility

Planes of Movement u Three primary planes –Sagittal –Frontal –Transverse

So How Can Knowledge of Planes Help Us? u More effectively determine cause(s) of (sport) injury u More effectively correct poor movement practices u More effectively...

Axis of Rotation u The line formed by the intersection of the two planes NOT involved in the movement. u Perpendicular to Plane of Movement.

Levers u Machines u composed of a rigid bar and a fulcrum. u eg. of rigid bar? u eg. of fulcrum?

Levers u 3 Classifications –1st Class - –2nd Class - –3rd Class -

Articular (Hyaline) Cartilage u Location: Covers articulating ends of bones (in synovial joints) u Purposes: –decrease friction –decrease load

Characteristics of AC u Highly Specialized u Can withstand relatively rigorous joint environment without failure. u Isolated tissue u Assists fitting of bone ends

Importance of AC u Least understood tissue in the body u Known Information: –Limited capacity for self-repair –does not follow Wolff’s Law (as we know it)

Factors affecting Breakdown of AC u High load u total number of stress peaks u changes in the intrinsic molecular and microscopic structure of AC u changes in its mechanical properties

How does Breakdown of AC occur? u loosens the collagen matrix u decrease in stiffness u increase in permeability

Special Cases u Disruption of Load carrying capacity of AC –Knee Meniscectomy –Ligament Rupture –Abnormal Joint Articulation –Cartilage degeneration –Excessive loads and load distribution disruptions

Joint Degeneration u Sport Examples: