1. 8
Joints: Part A

2. Joints (Articulations)
Articulation—site where two or more bones meet
Functions of joints:
Give skeleton mobility
Hold skeleton together

3. Classification of Joints
There are two ways to classify joints: Functional and Structural
Functional Classification of joints is based on amount of movement allowed by the joint
Synarthroses—immovable
Amphiarthroses—slightly movable
Diarthroses—freely movable

4. Classification of Joints
Structural Classification of Joints - Based on material binding bones together and whether or not a joint cavity is present (Fibrous, Cartilagenous, Synovial)
Three types of fibrous joints:
Sutures-occur only between skull bones; jagged articulations w/ short fibers btwn.
Syndesmoses- bones connected by ligaments, cords/bands of CT
Gomphoses –a peg in socket joint; the only example is a tooth in its bony alveolar socket

5. Joint held together with very short,
(a) Suture
Joint held together with very short,
interconnecting fibers, and bone edges
interlock. Found only in the skull.
Suture
line
Dense
fibrous
connective
tissue
Figure 8.1a

6. (b) Syndesmosis Joint held together by a ligament.
Fibrous tissue can vary in length, but
is longer than in sutures.
Fibula
Tibia
Ligament
Figure 8.1b

7. (c) Gomphosis “Peg in socket” fibrous joint. Periodontal
ligament holds tooth in socket.
Socket of
alveolar
process
Root of
tooth
Periodontal
ligament
Figure 8.1c

8. Classification of Joints
Cartilagenous Joints:
Two types of cartilagenous joints
Synchondroses- a bar of hyaline cartilage unites bone; mostly all are synarthrotic; (ex. epiphyseal plates in children)
Symphyses – articular surfaces of bones covered with hyaline which is fused to an intervening pad of fibrocartilage (ex. intervertebral discs)

9. Bones united by hyaline cartilage
(a) Synchondroses
Bones united by hyaline cartilage
Sternum
(manubrium)
Epiphyseal
plate (temporary
hyaline cartilage
joint)
Joint between
first rib and
sternum
(immovable)
Figure 8.2a

10. Bones united by fibrocartilage
(b) Symphyses
Bones united by fibrocartilage
Body of vertebra
Fibrocartilaginous
intervertebral
disc
Hyaline cartilage
Pubic symphysis
Figure 8.2b

11. Synovial Joints General Structures of Synovial Joints
Articular cartilage: pad of hyaline cartilage on ends of long bones
Joint (synovial) cavity: small potential space; contains synovial fluid
A double-layered joint capsule : an outer fibrous capsule (dense irregular CT) and an inner synovial membrane (loose CT)

12. Synovial Joints General Structures of Synovial Joints
Synovial fluid- a viscous fluid occupying joint cavity; lubricates and nourishes articular cartilage
May have wedges of fibrocartilage separating the articular surfaces called: menisci
Fibrous (bursae) lined with: synovial membrane contains synovial fluid and acts as friction reducing ball bearings

13. Ligament Joint cavity (contains synovial fluid) Articular (hyaline)
cartilage
Fibrous
capsule
Articular
capsule
Synovial
membrane
Periosteum
Figure 8.3

14. Subacromial bursa Humerus resting Cavity in bursa containing
synovial fluid
Humerus
moving
Figure 8.4b

15. Types of Synovial Joints
Plane-Nonaxial joints, short gliding movements
Hinge -Uniaxial joints, flexion and extension only
Pivot – Uniaxial joints, rotation
Condyloid - Biaxial joints, permit all angular movements
Saddle – Biaxial, more movement than condyloid
Ball and socket - Multiaxial joints; the most freely moving synovial joints

16. Plane joint (intercarpal joint)f
Nonaxial
Uniaxial
Biaxial
Multiaxial c b a
Plane joint (intercarpal joint) a e d
Figure 8.7a

17. Hinge joint (elbow joint)f
Nonaxial
Uniaxial
Biaxial
Multiaxial c b b
Hinge joint (elbow joint) a e d
Figure 8.7b

18. Pivot joint (proximal radioulnar joint)f
Nonaxial
Uniaxial
Biaxial
Multiaxial c b c
Pivot joint (proximal radioulnar joint) a e d
Figure 8.7c

19. (metacarpophalangeal joint)f
Nonaxial
Uniaxial
Biaxial
Multiaxial c b d
Condyloid joint
(metacarpophalangeal joint) a e d
Figure 8.7d

20. Saddle joint (carpometacarpal joint of thumb)
Nonaxial
Uniaxial
Biaxial
Multiaxial c b e
Saddle joint (carpometacarpal joint
of thumb) a e d
Figure 8.7e

21. Ball-and-socket joint (shoulder joint)f
Nonaxial
Uniaxial
Biaxial
Multiaxial c b f
Ball-and-socket joint (shoulder joint) a e d
Figure 8.7f

22. Common Joint Injuries
Sprains - Ligaments are stretched or torn; slow to repair themselves
Cartilage tears - Due to compression and shear stress, fragments may cause joint to lock or bind; Cartilage rarely repairs itself
Dislocations – Bones are forced out of alignment

23. Torn
meniscus
Figure 8.14

24. Inflammatory and Degenerative Conditions
Bursitis - Inflammation of a bursa, usually caused by a blow or friction
Tendonitis - Inflammation of tendon sheaths typically caused by overuse

25. Arthritis
Symptoms; pain, stiffness, and swelling of a joint
Acute forms: caused by bacteria, treated with antibiotics
Chronic forms: osteoarthritis, rheumatoid arthritis, and gouty arthritis

26. 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 joints
Intertarsal joints
Between articular processes of vertebrae

27. (a) Gliding movements at the wrist
Figure 8.5a

28. Movements that occur along the sagittal plane:
Angular Movements
Movements that occur along the sagittal plane:
Flexion—decreases the angle of the joint
Extension— increases the angle of the joint
Hyperextension—excessive extension beyond normal range of motion

29. (b) Angular movements: flexion, extension, and
Hyperextension
Extension
Flexion
(b) Angular movements: flexion, extension, and
hyperextension of the neck
Figure 8.5b

30. Extension Hyperextension Flexion
(c) Angular movements: flexion, extension, and hyperextension of the vertebral column
Figure 8.5c

31. (d) Angular movements: flexion and extension at the shoulder and knee
Figure 8.5d

32. Movements that occur along the frontal plane:
Angular Movements
Movements that occur along the frontal plane:
Abduction—movement away from the midline
Adduction—movement toward the midline
Circumduction—flexion + abduction + extension + adduction of a limb so as to describe a cone in space

33. Abduction Circumduction Adduction
(e) Angular movements: abduction, adduction, and circumduction of the upper limb at the shoulder
Figure 8.5e

34. The turning of a bone around its own long axis Examples:
Rotation
The turning of a bone around its own long axis
Examples:
Between C1 and C2 vertebrae
Rotation of humerus and femur

35. (f) Rotation of the head, neck, and lower limb
Lateral
rotation
Medial
rotation
(f) Rotation of the head, neck, and lower limb
Figure 8.5f

36. Movements of radius around ulna:
Special Movements
Movements of radius around ulna:
Supination - lateral rotation of hands
Pronation - medial rotation of hands

37. (a) Pronation (P) and supination (S)
(radius
rotates
over ulna)
Supination
(radius and
ulna are
parallel)
(a) Pronation (P) and supination (S)
Figure 8.6a

38. Special Movements Movements of the foot:
Dorsiflexion - upward movement
Plantar flexion - downward movement

39. (b) Dorsiflexion and plantar flexion
Figure 8.6b

40. Special Movements Movements of the foot:
Inversion - turn sole medially
Eversion - turn sole laterally

41. (c) Inversion and eversion
Figure 8.6c

42. Movements in a transverse plane:
Special Movements
Movements in a transverse plane:
Protraction- anterior movement
Retraction-posterior movement

43. (d) Protraction and retraction
of mandible
Retraction
of mandible
(d) Protraction and retraction
Figure 8.6d

44. Special Movements
Elevation - lifting a body part superiorly
Depression - moving a body part inferiorly

45. (e) Elevation and depression
of mandible
Depression
of mandible
(e) Elevation and depression
Figure 8.6e

46. Special Movements
Opposition of the thumb -Movement in the saddle joint so that the thumb touches the tips of the other fingers

47. Opposition
(f) Opposition
Figure 8.6f