1. Chapter 9: Articulations

2. Articulations
Body movement occurs at joints (articulations) where 2 bones connect

3. Joint Structure
Determines direction and distance of movement (range of motion)
Joint strength decreases as mobility increases

4. Functional Classifications
Synarthrosis:
no movement
Amphiarthrosis:
little movement
Diarthrosis:
more movement

5. Synarthroses Also called immovable joints
Fibrous or cartilaginous connections
May fuse over time

6. Amphiarthroses Also called slightly moveable joints
Fibrous or cartilaginous connections

7. Diarthroses Synovial joints Also called freely moveable joints
Subdivided by type of motion

8. Structural Classifications
Bony
Fibrous
Cartilaginous
Synovial

9. Synarthroses (Immovable Joints)
Are very strong
Edges of bones may touch or interlock

10. 4 Types of Synarthrotic Joints
Suture
Gomphosis
Synchondrosis
Synostosis

11. Suture Bones interlocked Are bound by dense fibrous connective tissue
Are found only in skull

12. Gomphosis Fibrous connection (periodontal ligament)
Binds teeth to sockets

13. Synchondrosis Is a rigid cartilaginous bridge between 2 bones:
epiphyseal cartilage of long bones
between vertebrosternal ribs and sternum

14. Synostosis Fused bones, immovable:
- two bones fuse together and boundary
disappears
metopic suture of skull (frontal suture)
epiphyseal lines of long bones

15. Amphiarthroses More moveable than synarthrosis
Stronger than freely movable joint

16. 2 Types of Amphiarthroses
Syndesmosis:
bones connected by ligaments
distal articulation between tibia/fibula
Symphysis:
bones separated by fibrocartilage

17. Synovial Joints (Diarthroses)
Also called moveable joints
At ends of long bones
Within articular capsules
Lined with synovial membrane

18. Articular Cartilages
Pad articulating surfaces within articular capsules:
prevent bones from touching
Smooth surfaces lubricated by synovial fluid:
reduce friction

19. Synovial Fluid
Contains slippery proteoglycans secreted by fibroblasts

20. Functions of Synovial Fluid
Lubrication
Nutrient distribution
Shock absorption

21. Synovial Joints: Accessory Structures
Cartilages
Fat pads
Ligaments
Tendons
Bursae

22. Cartilages
Cushion the joint:
fibrocartilage meniscus (articular disc)

23. Fat Pads
Superficial to the joint capsule
Protect articular cartilages

24. Accessory Ligaments Support, strengthen joints Sprain:
ligaments with torn collagen fibers

25. Tendons
Attach to muscles around joint
Help support joint

26. Bursae Pockets of synovial fluid
Cushion areas where tendons or ligaments rub

27. Synovial Joints: Stabilizing Factors
Prevent injury by limiting range of motion:
collagen fibers (joint capsule, ligaments)
articulating surfaces and menisci
other bones, muscles, or fat pads
tendons of articulating bones

28. Injuries Dislocation (luxation): Subluxation:
articulating surfaces forced out of position
damages articular cartilage, ligaments, joint capsule
Subluxation:
a partial dislocation

29. Types of Dynamic Motion
Linear motion (gliding)
Angular motion
Rotation

30. Linear Motion
Pencil maintains vertical orientation, but changes position
Figure 9–2a, b

31. Angular Motion Pencil maintains position, but changes orientation
Figure 9–2c

32. Circumduction
Circular angular motion
Figure 9–2d

33. Rotation Pencil maintains position and orientation, but spins
Figure 9–2e

34. Planes (Axes) of Dynamic Motion
Monaxial (1 axis)
Biaxial (2 axes)
Triaxial (3 axes)

35. Types of Movements at Synovial Joints
Terms describe:
plane or direction of motion
relationship between structures

36. Linear Motion Also called gliding 2 surfaces slide past each other:
between carpal or tarsal bones

37. Flexion
Figure 9–3a

38. Flexion Angular motion Anterior–posterior plane
Reduces angle between elements

39. Extension Angular motion Anterior–posterior plane
Increases angle between elements

40. Hyperextension
Angular motion
Extension past anatomical position

41. Abduction
Figure 9–3b, c

42. Abduction Angular motion Frontal plane
Moves away from longitudinal axis

43. Adduction
Angular motion
Frontal plane
Moves toward longitudinal axis

44. Circumduction Circular motion without rotation Angular motion
Figure 9–3d

45. Rotation
Figure 9–4

46. Rotation Direction of rotation from anatomical position
Relative to longitudinal axis of body

47. Rotation Left or right rotation Medial rotation (inward rotation):
rotates toward axis
Lateral rotation (outward rotation):
rotates away from axis

48. Pronation and Supination
rotates forearm, radius over ulna
Supination:
forearm in anatomical position

49. Inversion and Eversion
Figure 9–5a

50. Inversion and Eversion
twists sole of foot medially
Eversion:
twists sole of foot laterally

51. Dorsiflexion and Plantar Flexion
Figure 9–5b

52. Dorsiflexion and Plantar Flexion
flexion at ankle (lifting toes)
Plantar flexion:
extension at ankle (pointing toes)

53. Opposition Thumb movement toward fingers or palm (grasping)
Figure 9–5c

54. Protraction and Retraction
Figure 9–5d

55. Protraction and Retraction
moves anteriorly
in the horizontal plane (pushing forward)
Retraction:
opposite of protraction
moving anteriorly (pulling back)

56. Elevation and Depression
Figure 9–5e

57. Elevation and Depression
moves in superior direction (up)
Depression:
moves in inferior direction (down)

58. Lateral Flexion
Bends vertebral column from side to side
Figure 9–5f

59. Classification of Synovial Joints by Shape
Gliding
Hinge
Pivot
Ellipsoidal
Saddle
Ball-and-socket

60. Gliding Joints Flattened or slightly curved faces
Limited motion (nonaxial)
Figure 9–6 (1 of 6)

61. Hinge Joints Angular motion in a single plane (monaxial)
Figure 9–6 (2 of 6)

62. Pivot Joints
Rotation only (monaxial)
Figure 9–6 (3 of 6)

63. Ellipsoidal Joints Oval articular face within a depression
Motion in 2 planes (biaxial)
Figure 9–6 (4 of 6)

64. Saddle Joints
2 concave faces, straddled (biaxial)
Figure 9–6 (5 of 6)

65. Ball-and-Socket Joints
Round articular face in a depression (triaxial)
Figure 9–6 (6 of 6)

66. KEY CONCEPT A joint can’t be both mobile and strong
The greater the mobility, the weaker the joint
Mobile joints are supported by muscles and ligaments, not bone-to-bone connections

67. Intervertebral Articulations
Figure 9–7

68. Intervertebral Articulations
C2 to L5 spinal vertebrae articulate:
at inferior and superior articular processes (gliding joints)
between adjacent vertebral bodies (symphyseal joints)

69. Intervertebral Discs Intervertebral discs: pads of fibrocartilage
separate vertebral bodies

70. Verterbral Joints Also called symphyseal joints
As vertebral column moves:
nucleus pulposus shifts
disc shape conforms to motion

71. Intervertebral Ligaments
Bind vertebrae together
Stabilize the vertebral column

72. Damage to Intervertebral Discs
Figure 9–8

73. Damage to Intervertebral Discs
Slipped disc:
bulge in anulus fibrosus
invades vertebral canal
Herniated disc:
nucleus pulposus breaks through anulus fibrosus
presses on spinal cord or nerves

74. Movements of the Vertebral Column
Flexion:
bends anteriorly
Extension:
bends posteriorly
Lateral flexion:
bends laterally
Rotation

75. The Shoulder Joint
Figure 9–9a

76. The Shoulder Joint
Figure 9–9b

77. The Shoulder Joint Also called the glenohumeral joint:
allows more motion than any other joint
is the least stable
supported by skeletal muscles, tendons, ligaments

78. Structure of the Shoulder Joint
Ball-and-socket diarthrosis
Between head of humerus and glenoid cavity of scapula

79. Socket of the Shoulder Joint
Glenoid labrum:
deepens socket of glenoid cavity
fibrocartilage lining
extends past the bone

80. Processes of the Shoulder Joint
Acromion (clavicle) and coracoid process (scapula):
project laterally, superior to the humerus
help stabilize the joint

81. Shoulder Separation
Dislocation of the shoulder joint

82. Shoulder Muscles Also called rotator cuff: supraspinatus infraspinatus
subscapularis
teres minor

83. The Elbow Joint
Figure 9–10

84. The Elbow Joint A stable hinge joint
With articulations between humerus, radius, and ulna

85. Articulations of the Elbow
Humeroulnar joint:
largest articulation
trochlea of humerus and trochlear notch of ulna
limited movement
Humeroradial joint:
smaller articulation
capitulum of humerus and head of radius

86. The Hip Joint
Figure 9–11a

87. The Hip Joint
Figure 9–11b, c

88. The Hip Joint Also called coxal joint
Strong ball-and-socket diarthrosis
Wide range of motion

89. Structures of the Hip Joint
Head of femur fits into it
Socket of acetabulum
Which is extended by fibrocartilage acetabular labrum

90. The Knee Joint
Figure 9–12a, b

91. The Knee Joint
Figure 9–12c, d

92. The Knee Joint A complicated hinge joint
Transfers weight from femur to tibia

93. Articulations of the Knee Joint
2 femur–tibia articulations:
at medial and lateral condyles
1 between patella and patellar surface of femur

94. Menisci of the Knee Medial and lateral menisci: fibrocartilage pads
at femur–tibia articulations
cushion and stabilize joint
give lateral support

95. Locking Knees Standing with legs straight:
“locks” knees by jamming lateral meniscus between tibia and femur

96. 7 Ligaments of the Knee Joint
Patellar ligament (anterior)
2 popliteal ligaments (posterior)
Anterior and posterior cruciate ligaments (inside joint capsule)
Tibial collateral ligament (medial)
Fibular collateral ligament (lateral)

97. Rheumatism
A pain and stiffness of skeletal and muscular systems

98. Arthritis
All forms of rheumatism that damage articular cartilages of synovial joints

99. Osteoarthritis
Caused by wear and tear of joint surfaces, or genetic factors affecting collagen formation
Generally in people over age 60

100. Rheumatoid Arthritis An inflammatory condition
Caused by infection, allergy, or autoimmune disease
Involves the immune system

101. Gouty Arthritis Occurs when crystals (uric acid or calcium salts):
form within synovial fluid
due to metabolic disorders

102. Joint Immobilization Reduces flow of synovial fluid
Can cause arthritis symptoms
Treated by continuous passive motion (therapy)