1. Joints
Part A 8

2. Joints (Articulations)
Weakest parts of the skeleton
Articulation – site where two or more bones meet
Functions of joints
Give the skeleton mobility
Hold the skeleton together

3. Classification of Joints: Structural
Structural classification focuses on the material binding bones together and whether or not a joint cavity is present
The three structural classifications are:
Fibrous
Cartilaginous
Synovial

4. Classification of Joints: Functional
Functional classification is based on the amount of movement allowed by the joint
The three functional classes of joints are:
Synarthroses – immovable
Amphiarthroses – slightly movable
Diarthroses – freely movable

5. Fibrous Structural Joints
The bones are joined by fibrous tissues
There is no joint cavity
Most are immovable
There are three types – sutures, syndesmoses, and gomphoses

6. Fibrous Structural Joints: Sutures
Occur between the bones of the skull
Comprised of interlocking junctions completely filled with connective tissue fibers
Figure 8.1a

7. Fibrous Structural Joints: Syndesmoses
Bones are connected by a fibrous tissue ligament
Movement varies from immovable to slightly variable
Examples include the connection between the tibia and fibula, and the radius and ulna

8. Fibrous Structural Joints: Gomphoses
The peg-in-socket fibrous joint between a tooth and its alveolar socket
The fibrous connection is the periodontal ligament

9. Articulating bones are united by cartilage Lack a joint cavity
Cartilaginous Joints
Articulating bones are united by cartilage
Lack a joint cavity
Two types – synchondroses and symphyses

10. Cartilaginous Joints: Synchondroses
Figure 8.2a, b

11. Cartilaginous Joints: Symphyses
Hyaline cartilage covers the articulating surface of the bone and is fused to an intervening pad of fibrocartilage
Figure 8.2c

12. All are freely movable diarthroses
Synovial Joints
Those joints in which the articulating bones are separated by a fluid-containing joint cavity
All are freely movable diarthroses
Examples – all limb joints, and most joints of the body

13. Synovial Joints: General Structure
Synovial joints all have the following
Articular cartilage
Joint (synovial) cavity
Articular capsule
Synovial fluid
Reinforcing ligaments

14. Synovial Joints: General Structure
Figure 8.3a, b

15. Synovial Joints: Friction-Reducing Structures
Bursae – flattened, fibrous sacs lined with synovial membranes and containing synovial fluid
Common where ligaments, muscles, skin, tendons, or bones rub together
Tendon sheath – elongated bursa that wraps completely around a tendon

16. Synovial Joints: Friction-Reducing Structures
Figure 8.4

17. Synovial Joints: Range of Motion
Nonaxial – slipping movements only
Uniaxial – movement in one plane
Biaxial – movement in two planes
Multiaxial – movement in or around all three planes

18. One flat bone surface glides or slips over another similar surface
Gliding Movements
One flat bone surface glides or slips over another similar surface
Examples – intercarpal and intertarsal joints, and between the flat articular processes of the vertebrae

19. Flexion — bending movement that decreases the angle of the joint
Angular Movement
Flexion — bending movement that decreases the angle of the joint
Extension — reverse of flexion; joint angle is increased
Dorsiflexion and plantar flexion — up and down movement of the foot
Abduction — movement away from the midline
Adduction — movement toward the midline
Circumduction — movement describes a cone in space

20. Gliding Movement
Figure 8.5a

21. Angular Movement
Figure 8.5b

22. Angular Movement
Figure 8.5c, d

23. Angular Movement
Figure 8.5e, f

24. The turning of a bone around its own long axis
Rotation
The turning of a bone around its own long axis
Examples
Between first two vertebrae
Hip and shoulder joints
Figure 8.5g

25. Supination and pronation Inversion and eversion
Special Movements
Supination and pronation
Inversion and eversion
Protraction and retraction
Elevation and depression
Opposition

26. Special Movements
Figure 8.6a

27. Special Movements
Figure 8.6b

28. Special Movements
Figure 8.6c

29. Special Movements
Figure 8.6d

30. Special Movements
Figure 8.6e