I. Classification of Joints Diagram
- Structural classification is based on material binding bones together and
presence/absence of a cavity
- Types of joints: Fibrous, Cartilaginous, Synovial.
- Functional classification is based on extent of movement:
- Synarthroses - immovable joints (e.g. sternocostal,
- Amphiarthroses - slightly movable (e.g. vertebral
bodies, pubic bones)
- Diarthroses - freely movable (most appendicular)
II. Fibrous Joints (fibrous tissue, no cavity)
- Few amphiarthrotic, mostly synarthrotic
- Three types: sutures, syndesmoses, gomphoses
- Sutures - e.g. skull, interdigitating articulating
bone; sutures contain dense fibrous connective tissue until adulthood when
they ossify (synostoses), becoming bony junctions.
- Syndesmoses - bones connected by a filamentous sheet or
cord (ligament or interosseous membrane); fibers are longer than in sutures
but are only slightly more resilient, therefore still synarthrotic (e.g.
tibiofibular joint, distal ends).
- Gomphoses - articulation of tooth with bony alveolar
socket (fibrous connection = periodontal ligament).
III. Cartilaginous Joints (articulating bones united by cartilage)
- Lack a joint cavity
- Two types: synchondroses and symphyses
- Synchondroses - hyaline cartilage unites bones at a
synchondrosis which are usually temporary joints (sites of bone growth);
cartilage is replaced by bone (become synostotic); e.g. synarthrotic
epiphyseal plate and manubrium/first rib & functionally amphiarthrotic
- Symphyses - articular surfaces of bones covered by
hyaline cartilage fused to an intervening pad or plate; compressible,
resilient, and functionally amphiarthrotic; e.g. pubic symphysis (junction
of pubic bones) and intervertebral discs.
Synovial Joints (articular bones separated by a fluid-filled joint
- Joints of limbs, diarthrotic
- Five distinct features:
- Articular cartilage (hyaline)
- Joint cavity
- Articular capsule, containing:
- fibrous capsule (external)
- synovial membrane (internal)
- Synovial fluid
- Reinforcing ligaments
- intrinsic - parallel bundles of fibers within fibrous capsule
- extracapsular - extend bone to bone outside capsule
- intracapsular - located inside synovial cavity
- Some synovial joints contain fatty pads between fibrous capsules and
synovial membrane (egs knee and hip joint); others have articular discs
(menisci) which are fibrocartilaginous discs extending inward
from articular capsule and divide synovial cavity into two.
- Synovial joints have supportive structures called bursae. DIAGRAM These
structures are flattened sacs lined with synovial membrane and contain a thin
film of synovial fluid. Bursae are located where ligaments, muscles, and
tendons overlie and rub against bone. Elongated bursae wrapping around tendons
are referred to as tendon sheaths.
- Movements by synovial joints:
- Axis of motion:
- Nonaxial - slipping movements
- Uniaxial - movement in one plane; phalanges, radius/ulna, femur/tibia
- Biaxial - movement in two planes; occipital bone/atlas
- Multiaxial - movement in three planes; scapula/humerus, and coxal
- Type of motion:
- Gliding - bones displaced in relation to one another, e.g.
intercarpal, intertarsal, and intervertebral joints
- Angular - changing the angle between two bones, egs....
- Flexion (bending, decreasing the angle)
- Extension (stretching, increasing the angle)
- Abduction (move away)
- Adduction (move toward)
- Circumduction (draw around, conical shape)
- Rotation - turning movement of a bone around its own axis (e.g. atlas
and axis of vertebrae).
- Types of synovial joints Diagram
Gliding - intercarpal and intertarsal
Hinge - elbow
Pivot - head of radius in radial norch
Condyloid - metacarpophalangeal
Saddle - carpometacarpal
Ball-and-socket - shoulder
V. Clinical Terms
- Sprain - stretching/tearing of a ligament
- Dislocation - (luxation), bones forced out of their normal position
- Bursitis - inflammation of bursa
- Arthritis - inflammatory or degenerative disease; synovial membrane
thickens, fluid production decreases, increase in friction and pain. Types:
- Osteo arthritis - degenerative
- Rheumatoid arthritis - autoimmune
- Gouty arthritis - uric acid accumulation
- Synovitis - inflammation of synovial membrane
- Tendinitis - inflammation of tendon sheaths