Joints/Articulations

Articulations - any place two bones 'meet'
Arthrology is the study of articulations

Classification of Joints:
Joints are named for bones involved
Classification based on anatomical arrangement of two bones and range of motion

3 Physiological Classes:
Immovable
Slightly movable
Freely movable

4 Anatomical Classes:
Bony
Also called synostoses
Immovable
Two bones ossified together ex: epiphyseal line in an adult

Fibrous
Also called synarthroses
Two bones bound by collagen fibers
3 subclasses:
   Sutures - collagen fibers are short (between flat bones and skull)
   Gomphoses - immovable collagen fibers (between teeth and mandible, maxilla)
     Peridontal ligament
   Syndesmoses - slightly movable, joined by long fibers (tibia to fibula, radius to ulna)
     Interosseous membrane

Cartilaginous
Also called ampirthroses
Two bones bound by cartilage
All semi-movable
2 subclasses:
   Synchondroses - bound by hyaline cartilage (epiphyseal plate in child)
   Synphysis - bound by fibrocartilage (intervertebral discs)

Synovial
Also called diarthroses
Mostly freely movable

General Anatomy:
Articular cartilage (line capsule)
Articular cavity and synovial fluid (knee, shoulder)
Articulate capsule (surround epiphyses of bones)

Accessory Structure:
   Menisci - pad of fibrocartilage
   Tendons - muscle to bone
   Ligaments - bone to bone, extrinsic or intrinsic
   Bursae - packet of synovial fluid

Classes of Synovial Joints:
Based on patterns of movement
   Monaxial
   Biaxial
   Multiaxial

Hinge joints - monaxial - two flat surfaces (elbow)

Gliding joints - limited monaxial - both faces smooth (carpals)

Pivot joints - monaxial - rotational (C1-C2)

Saddle joints - biaxial - linear angular (twiddle thumb)

Condyloid joints - biaxial - (carpals)

Ball and Socket joints - multiaxial (shoulders, hips)

What limits ROM?
Structure and action of muscles
Structure of articular surface of bones
Strength and tautness of ligaments, tendons, and joint capsules