1. Joints and Skeletal Articulations5

2. Joints (Articulations) - know
Articulation – site where two or more bones meet
Functions of joints
Give the skeleton mobility
Hold the skeleton together
Joints are a weak part of the skeleton and are often injured

3. Classification of Joints: Structural - know
Structural classification focuses on the material binding bones together and whether or not a joint cavity is present
The three structural classifications are:
Fibrous (cranial bones)
Cartilaginous (ribs – sternum)
Synovial (knee)

4. Classification of Joints: Functional - know
Functional classification is based on the amount of movement allowed by the joint
The three functional classes of joints are:
Synarthroses – immovable (cranial bones)
Amphiarthroses – slightly movable (vertebrae)
Diarthroses – freely movable (knee)
We will discuss joints based on structural classification:

5. 1. Fibrous Joints (structural classification) - know
The bones are joined by fibrous tissues
There is no joint cavity
Most are immovable
There are three types – sutures, syndesmoses, and gomphoses

6. a. Fibrous Joints: Sutures - know
Occur between the bones of the skull
*Comprised of interlocking junctions completely filled with connective tissue fibers*
Bind bones tightly together, but allow for growth during youth
Skull bones fuse and are called synostoses
Begins as early as age 10-15, generally complete by age 30-50

7. Fibrous Structural Joints: Sutures - example
Figure 8.1a

8. b. Fibrous Joints: Syndesmoses - know
*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
b. Fibrous Joints: Syndesmoses - know

9. Fibrous Joints: Syndesmoses - example
Figure 8.1b

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

11. 2. Cartilaginous Joints (structural classification) - know
Articulating bones are united by cartilage
*Lack a joint cavity*
Two types – synchondroses and symphyses
2. Cartilaginous Joints (structural classification) - know

12. a. Cartilaginous Joints: Synchondroses - understand
A bar or plate of hyaline cartilage unites the bones
All synchondroses are synarthrotic (immovable)
Examples include:
Epiphyseal plates of children
Joint between the costal cartilage of the 1st rib and the sternum

13. Cartilaginous Joints: Synchondroses - example
Figure 8.2a, b

14. b. Cartilaginous Joints: Symphyses - understand
Hyaline cartilage covers the articulating surface of the bone and is fused to an intervening pad of fibrocartilage
Amphiarthrotic (slightly movable) joints designed for strength and flexibility
Examples include intervertebral joints and the pubic symphysis of the pelvis (expansion in female for childbirth)

15. Cartilaginous Joints: Symphyses - example

16. 3. Synovial Joints (structural classification) - know
Most common
*Those joints in which the articulating bones are separated by a fluid-containing joint cavity*
All are diarthroses (freely movable)
Examples – all limb joints, and most joints of the body (regardless of size!)

17. Synovial Joints: General Structure - understand
All synovial joints have:
Articular cartilage
Joint (synovial) cavity
Articular capsule
Synovial fluid
Reinforcing ligaments

18. Synovial Joints: General Structure - example
Cadaver dissection

19. Synovial Joints: Friction-Reducing Structures - know
These friction-reducing structures are found in synovial joints and are common where ligaments, muscles, skin, tendons, or bones rub together:
Bursae – flattened, fibrous sacs lined with synovial membranes and containing synovial fluid
Tendon sheath – elongated bursa that wraps completely around a tendon

20. Synovial Joints: Friction-Reducing Structures – understand complexity

21. Synovial Joints: Stability - understand
Stability is determined by:
Articular surfaces – shape determines what movements are possible
Ligaments – unite bones and prevent excessive or undesirable motion
Muscle tone
Tendons of muscles cross the joint and help stabilize it
The tendons are kept tight by muscle tone

22. Synovial Joints: Movement - know
The two muscle attachments across a joint are:
Origin – attachment to the immovable bone
Insertion – attachment to the movable bone
Described as movement along transverse, frontal, or sagittal planes

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

24. 1. Gliding Movements - understand
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
1. Gliding Movements - understand

25. Angular Movement – know – (important slide!)
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

26. Articulations

27. Gliding Movement – know (be able to identify)

28. Angular Movement – know (be able to identify)

29. Angular Movement – know (be able to identify)

30. Angular Movement – know (be able to identify)

31. Rotation – know (be able to identify)
The turning of a bone around its own long axis
Examples
Between atlas and axis
Hip and shoulder joints

32. Special Movements – know (be able to identify)
Supination and pronation
Inversion and eversion
Protraction and retraction
Elevation and depression
Opposition
Special Movements – know (be able to identify)

33. Special Movements – know (be able to identify)

34. Special Movements – know (be able to identify)

35. Special Movements – know (be able to identify)
Figure 8.6c

36. Special Movements – know (be able to identify)
Figure 8.6d

37. Special Movements – know (be able to identify)

38. How joints are classified
Examples
Link to table of joints
Medical school site: Joints
Arthritis Foundation Website

39. Types of Joints: examples
Various kinds of joints. Fibrous: A, syndesmosis (tibiofibular); B, suture (skull). Cartilaginous: C, symphysis (vertebral bodies); D, synchondrosis (first rib and sternum). Synovial: E, condyloid (wrist); F, gliding (radioulnar); G, hinge or ginglymus (elbow); H, ball and socket (hip); I, saddle (carpometacarpal of thumb); J, pivot (atlantoaxial).