1. Articulations (Joints)

2. Connect 2 bones.
Classified by structure or function

3. Joint classification Classification by structure
1. Fibrous joints
- bones held together by fibrous connective tissue
2. Cartilagenous joints
- bones held together by cartilage
3. Synovial joints
- complex structure with cartilage and cavities
Classification by function
1. Synarthroses
Immovable joints
2. Amphiarthrose
Slightly movable joints
3. Diarthroses
Freely movable joints

4. General background 1 extra joint category Bony joint (synostosis)
Immobile (immovable)
Fond when 2 bones ossify together (essentially merge or weld together)
Some cranial sutures (fissures in the cranium) become ossified
When the growth plate fuses/calcifies over (joining the epiphysis and diaphysis in long bones)

5. Fibrous joint (synarthrosis)
1. Suture
2. Gomphosis
3. Syndesmosis

6. 1. Sutures
Suture: immobile joints in the skull (the fissures you see) through the thickness of the outer compact bone
-“serrate” = wavy lines (like a serrated knife)
- skull: parieta/frontal bones
“lap”/ “squamous” = diagonal line
Skull: temporal/parietal bones
“plane” / “butt” = straight line
Paired maxillary and palatine bones

7. 2. Gomphosis where teeth attach to bone
Tooth is “held in place” by fibrous peridontal ligament” made of collagen that originates from the jaw bone
Fibrous “joint” permits slight movement when biting
An important sensory mechanism that lets you know how hard or soft you are biting

8. Gingivitis (gum disease)
Bacterial infection destroys the ligament holding the teeth in place
Promoted by the presence of plaque

9. Scurvy A chronic lack of vitamin C leads to scurvy
Vitamin C is necessary for collagen synthesis
With decreased collagen synthesis, joints are weakened, wounds do not heal well.
How do you treat scurvy?

10. 3. Syndesmosis Colllagen fibers bind 2 bones
More mobility than suture or gomphosis, but still very limited
Tibia – fibula at distal end
Radius – ulna at distal ends

11. Tibia/fibula Radius/ulna
Note how far apart the radius/ulna are from one another compared to the tibia/fibula. This is one reason why your forearm is more “mobile” or flexible than your lower leg.

12. Cartilaginous joints: (amphiarthrosis)
Synchondoses: when bone is bound /joined by hyaline cartilage
The growth plate in long bones
The first rib attaches to the sternum (ONLY the first rib)
Symphyses: where bones are joined by fibrous cartilage
Pubic bone (pelvis)
Between vertebrae

13. Trick question
How/why do infants and children have more joints than adults?

14. Synovial joints - Very complex
“synovial” joint because the joints are separated by a space (“synovial cavity”), where synovial fluid is retained
Synovial fluid rich in albumin (blood protein) and hyaluronic acid (a lubricant)

15. Synovial joints Joint membrane:
Outer fibrous capsule (continuous with the periosteum)
Inner synovial membrane secretes the synovial fluid into the joint capsule
Each bone involved in the joint is covered by articular cartilage  2 mm thick
-The bones making up the joint are “held together” by ligaments
Help to locate the bones in the correct “place” so that their articular cartilage “rides” correctly

16. Types of joints: classification by shape
Ball & Socket joints (hip and shoulder)
Hinge joints (ulna and femur…knee, fingers and toes)
Pivot joints (radius and ulna…forearm/elbow and the first 2 vertebrae of your spine)
Saddle joints (thumb, sternum/clavicle)
Condyloid joints (fingers)

17. Types of joints: classification by shape
Ball & Socket joints (hip and shoulder)
The ONLY multi-directional joints you have

18. Types of joints: classification by shape
Ball & Socket joints
Hinge joints (ulna and femur…knee, fingers and toes)
1 range of movement (flip-phone)

19. Types of joints: classification by shape
Ball & Socket
Hinge joints
Pivot joints (radius and ulna…forearm/elbow and the first 2 vertebrae of your spine)
When 1 bone spins on another, when you say no, or turn a door knob)

20. Types of joints: classification by shape
Ball & Socket joints
Hinge joints
Pivot joints
Saddle joints (thumb, sternum/clavicle)
2 ranges of motion (hold something tight = sagittal plane, spread hand = frontal plane)
Condyloid joints (fingers)
2 ranges of motion: make a fist = sagittal plane, spread fingers = frontal plane

21. Types of joints: classification by shape
Ball & Socket joints
Hinge joints
Pivot joints
Saddle joints
Condyloid joints
Gliding joints
Bone surface almost flat
Bones slide along each other
Ex: carpal bone, patella-femur

22. Complex joints
Many joints have characteristics of multiple joint types
Elbow is both a hinge joint (where ulna and humerus meet), as well as a pivot joint (where radius and ulna meet)
Knee is similar to the elbow joint, without as much flexibility (much stronger and limited)
Temporo-mandibular joint has both lateral and dorsal/ventral movement

23. Complex synovial joints
In a few joints (jaw = temporo-mandibular), (sternum/collarbone =sterno-clavicular), (ankle = distal tibia-fibula), there is an articular disc
In your knee, this is called a meniscus
for guidance of the knee bones
for shock absorption

24. Accessories to synovial joints
Other structures present in synovial joints:
Tendons: collagen-based connective tissue that hold muscle to bone
Ligaments: collagen-based connective tissue that hold bone to bone
Bursa: fibrous “sac” that holds synovial fluid
Wraps around muscles  prevent rubbing
“bursitis” = inflammation of the bursa
“tendon sheath”

25. Bursa

26. Movements of various joints
Your shoulder (ball and socket) is a good example of a joint that is “multiarticulate”
The ball and socket allows for:
Abduction of the arm (flap your arms like a bird, jumping jacks)
Flexion of the arm (extending to shake a hand or open a door)
Rotation of the arm (sweeping your desk)

27. Movements of various joints
Abduction = raising arms above head (moving away from the anatomical position in the FRONTAL PLANE)
Adduction = returning arms to side (returning to anatomical position in the FRONTAL PLANE)
The terms abduction and adduction refer to the ACTION, NOT THE APPENDAGE that you are moving (you can also abduct and adduct your legs at the hip joint).

28. Movements of various joints
Elevation = lifting body part in the FRONTAL PLANE (moving away from the anatomical position)
In this case, the model is raising their shoulders in the frontal or coronal plane
Depression = returning to anatomical position from elevation
These terms refer to movement FROM the anatomical position, as well as back TO the anatomical position. These movement terms also refer to the PLANE of movement. In this case, we are dealing with the FRONTAL or CORONAL plane.

29. Movements of various joints
Protraction = moving body part forward (anterior movement) in a transverse or horizontal direction
Retraction = posterior movement (“pushing out” his chest…he’s really pulling back his shoulders”)
With these terms, there is reference to direction and plane of movement, however, this DOES NOT refer to the movement FROM or TO the anatomical position.

30. Movements of various joints
Flexion = decreasing joint angle
In this case, the models elbow is in flexion
Extension = increasing joint angle to “zero position” (where it would “naturally rest)
Hyperextension = moving beyond the zero position
Note that this movement DOES NOT refer to the plane of a joint, is only refers to the ANGLE of the joint.

31. Movements of various joints
Hyperextension = moving beyond the zero position

32. Movements of various joints
Circumduction = 1 end of the joint remains stationary, the other end makes a CIRCLE.
Rotation = turning a joint longitudinally
on 1 bone of the joint

33. Movements of various joints
Supination =ONLY for FOREARM, when you turn your forearm so that the palms face forward or ventral (anatomical position)
Pronation = ONLY for the forearm, when you turn your forearm so that the palm faces posterior or dorsal

34. Movements of hand joints
Radial flexion = tilting the hand towards the thumb (towards the radius)
Ulnar flexion = tilting hand towards the pinky finger (towards the ulna)
Abduction of the FINGERS is when you spread your fingers apart
In terms of your fingers:
Flexion = curling fingers (like a fist)
Extension = pointing your fingers

35. Movements of hand joints
Your THUMB is turned 90 from the rest of your fingers, so the previous “terms” for finger movement are DIFFERENT for your thumb
Abduction = bring your thumb to your index finger (the “OK” sign)
Opposition = touch pinky with thumb
Reposition = return to “zero” from the opposition position
In terms of your THUMB:
Flexion = bending towards the palm of your hand
Extension = pointing thumb up (hitch-hiking)
Hyperextension = when you make a 90 angle between your thumb and index finger (straight up hitch hiker thumb)

36. Movements of foot/ankle joints
In terms of ANKLE movements
Dorsiflection = lift toes up (standing on your heels)
Zero position = feet flat on the ground, standing up
Plantar flexion = pointing toes down (standing on your toes)
In terms of your FEET:
Your ankle can “roll” just like your wrist can “wave”
Inversion = turning the plantar surface towards the median (standing on the outside of your feet)
Eversion = turning the plantar surface laterally (standing on the arches of your feet)

37. Complex joint: humero-scapular joint (shoulder)
The scapula is connected to the thorax only by the clavicle (collar bone)
Connection at the acromion process (look for a sharp hook)
The joint between the clavicle and acromion = acromial-clavicular joint

38. Humero-scapular joint
Posterior view
Anterior view
Note how the ligaments and tendons wrap around the joint to hold the head of the humerus into the glenoid cavity. Also note how shallow the “socket” on the scapula is; an effort to increase mobility of this joint

39. Loose ball and socket joint.
More mobility
Muscles and ligaments stabilize the joint

40. Complex joint: Elbow joint
Actually 2 joints in 1 area
Humero-ulnar joint
Humero-radial joint
Both enclosed by 1 single synovial joint capsule
3rd joint in the elbow: radio-ulnar joint
head of the radius - radial notch in the ulnus
important because it permits the forearm rotation (supine/prone) rotation
Your tibia/fibula (shins) cannot rotate as well

41. Features of the hand and wrist
Also remember that your hand and wrist comprise a number of different joint types: saddle, gliding and condyloid. Together, these joints give your hands and fingers a great deal of and mobility

42. Costovertebral joints

43. Hip joint: Coxal bone - femur

44. Knee and hip replacements

46. Rheumatoid arthritis
- An autoimmune disease

47. Osteoarthritis
- Bone degeneration due to old age

48. Osteoarthritis of the spinal cord

49. Bursitis
Accumulation of synovial fluid in the bursa – due to chronic or acute irritation
An extreme case!

50. Sprain and Strain
Sprain: ligament tear
Strain: Tendon or muscle tear