Joints

1
Chapter 8

• Joints

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
• Bind bones tightly together, but allow for growth
  during youth
• In middle age, skull bones fuse and are called
  synostoses

7
Fibrous Structural Joints Sutures
Figure 8.1a
8
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

9
Fibrous Structural Joints Syndesmoses
Figure 8.1b
10
Fibrous Structural Joints Gomphoses

• The peg-in-socket fibrous joint between a tooth
  and its alveolar socket
• The fibrous connection is the periodontal ligament

11
Cartilaginous Joints

• Articulating bones are united by cartilage
• Lack a joint cavity
• Two types synchondroses and symphyses

12
Cartilaginous Joints Synchondroses

• A bar or plate of hyaline cartilage unites the
  bones
• All synchondroses are synarthrotic
• Examples include
• Epiphyseal plates of children
• Joint between the costal cartilage of the first
  rib and the sternum

13
Cartilaginous Joints Synchondroses
Figure 8.2a, b
14
Cartilaginous Joints Symphyses

• Hyaline cartilage covers the articulating surface
  of the bone and is fused to an intervening pad of
  fibrocartilage
• Amphiarthrotic joints designed for strength and
  flexibility
• Examples include intervertebral joints and the
  pubic symphysis of the pelvis

15
Cartilaginous Joints Symphyses
Figure 8.2c
16
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

17
Synovial Joints General Structure

• Synovial joints all have the following
• Articular cartilage
• Joint (synovial) cavity
• Articular capsule
• Synovial fluid
• Reinforcing ligaments

18
Synovial Joints General Structure
Figure 8.3a, b
19
Table 8.2.1
20
Table 8.2.2
21
Table 8.2.3
22
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

23
Synovial Joints Friction-Reducing Structures
Figure 8.4
24
Synovial Joints Stability

• Stability is determined by
• Articular surfaces shape determines what
  movements are possible
• Ligaments unite bones and prevent excessive or
  undesirable motion

25
Synovial Joints Stability

• Muscle tone is accomplished by
• Muscle tendons across joints acting as
  stabilizing factors
• Tendons that are kept tight at all times by
  muscle tone

26
Synovial Joints Movement

• 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

27
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

28
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

29
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

30
Angular Movement

• Abduction movement away from the midline
• Adduction movement toward the midline
• Circumduction movement describes a cone in space

31
Gliding Movement
Figure 8.5a
32
Angular Movement
Figure 8.5b
33
Angular Movement
Figure 8.5c, d
34
Angular Movement
Figure 8.5e, f
35
Rotation

• The turning of a bone around its own long axis
• Examples
• Between first two vertebrae
• Hip and shoulder joints

Figure 8.5g
36
Special Movements

• Supination and pronation
• Inversion and eversion
• Protraction and retraction
• Elevation and depression
• Opposition

37
Special Movements
Figure 8.6a
38
Special Movements
Figure 8.6b
39
Special Movements
Figure 8.6c
40
Special Movements
Figure 8.6d
41
Special Movements
Figure 8.6e
42
Plane Joint

• Plane joints
• Articular surfaces are essentially flat
• Allow only slipping or gliding movements
• Only examples of nonaxial joints

Figure 8.7a
43
Types of Synovial Joints

• Hinge joints
• Cylindrical projections of one bone fits into a
  trough-shaped surface on another
• Motion is along a single plane
• Uniaxial joints permit flexion and extension only
• Examples elbow and interphalangeal joints

44
Hinge Joints
Figure 8.7b
45
Pivot Joints

• Rounded end of one bone protrudes into a
  sleeve, or ring, composed of bone (and possibly
  ligaments) of another
• Only uniaxial movement allowed
• Examples joint between the axis and the dens,
  and the proximal radioulnar joint

46
Pivot Joints
Figure 8.7c
47
Condyloid or Ellipsoidal Joints

• Oval articular surface of one bone fits into a
  complementary depression in another
• Both articular surfaces are oval
• Biaxial joints permit all angular motions
• Examples radiocarpal (wrist) joints, and
  metacarpophalangeal (knuckle) joints

48
Condyloid or Ellipsoidal Joints
Figure 8.7d
49
Saddle Joints

• Similar to condyloid joints but allow greater
  movement
• Each articular surface has both a concave and a
  convex surface
• Example carpometacarpal joint of the thumb

50
Saddle Joints
Figure 8.7e
51
Ball-and-Socket Joints

• A spherical or hemispherical head of one bone
  articulates with a cuplike socket of another
• Multiaxial joints permit the most freely moving
  synovial joints
• Examples shoulder and hip joints

52
Ball-and-Socket Joints
Figure 8.7f
53
Synovial Joints Knee

• Largest and most complex joint of the body
• Allows flexion, extension, and some rotation
• Three joints in one surrounded by a single joint
  cavity
• Femoropatellar joint
• Lateral and medial tibiofemoral joints

54
Synovial Joints Knee Ligaments and Tendons
Anterior View

• Tendon of the quadriceps femoris muscle
• Lateral and medial patellar retinacula
• Fibular and tibial collateral ligaments
• Patellar ligament

Figure 8.8c
55
Synovial Joints Knee Other Supporting
Structures

• Anterior cruciate ligament
• Posterior cruciate ligament
• Medial meniscus (semilunar cartilage)
• Lateral meniscus

56
Synovial Joints Knee Other Supporting
Structures
Figure 8.8b
57
Synovial Joints Knee Posterior Superficial
View

• Adductor magnus tendon
• Articular capsule
• Oblique popliteal ligament
• Arcuate popliteal ligament
• Semimembranosus tendon

Figure 8.8e
58
Synovial Joints Shoulder (Glenohumeral)

• Ball-and-socket joint in which stability is
  sacrificed to obtain greater freedom of movement
• Head of humerus articulates with the glenoid
  fossa of the scapula

59
Synovial Joints Elbow

• Hinge joint that allows flexion and extension
  only
• Radius and ulna articulate with the humerus

60
Synovial Joints Elbow

• Annular ligament
• Ulnar collateral ligament
• Radial collateral ligament

Figure 8.10a
61
Synovial Joints Elbow
Figure 8.10b
62
Synovial Joints Elbow
Figure 8.10d
63
Synovial Joints Shoulder Stability

• Weak stability is maintained by
• Thin, loose joint capsule
• Four ligaments coracohumeral, and three
  glenohumeral
• Tendon of the long head of biceps, which travels
  through the intertubercular groove and secures
  the humerus to the glenoid cavity
• Rotator cuff (four tendons) that encircles the
  shoulder joint and blends with the articular
  capsule

64
Synovial Joints Shoulder Stability
Figure 8.11a
65
Synovial Joints Shoulder Stability
Figure 8.11b
66
Synovial Joints Hip (Coxal) Joint

• Ball-and-socket joint
• Head of the femur articulates with the acetabulum
• Good range of motion, but limited by the deep
  socket and strong ligaments

67
Synovial Joints Hip Stability

• Acetabular labrum
• Iliofemoral ligament
• Pubofemoral ligament
• Ischiofemoral ligament
• Ligamentum teres

Figure 8.12a
68
Synovial Joints Hip Stability
Figure 8.12c, d
69
Temporomandibular Joint (TMJ)

• Mandibular condyle articulate with the temporal
  bone
• Two types of movement
• Hinge depression and elevation of mandible
• Side to side (lateral excursion) grinding of
  teeth

70
Temporomandibular Joint
Figure 8.13a, b
71
Sprains

• The ligaments reinforcing a joint are stretched
  or torn
• Partially torn ligaments slowly repair themselves
• Completely torn ligaments require prompt surgical
  repair

72
Cartilage Injuries

• The snap and pop of overstressed cartilage
• Common aerobics injury
• Repaired with arthroscopic surgery

73
Dislocations

• Occur when bones are forced out of alignment
• Usually accompanied by sprains, inflammation, and
  joint immobilization
• Caused by serious falls and are common sports
  injuries
• Subluxation partial dislocation of a joint

74
Inflammatory and Degenerative Conditions

• Bursitis
• An inflammation of a bursa, usually caused by a
  blow or friction
• Symptoms are pain and swelling
• Treated with anti-inflammatory drugs excessive
  fluid may be aspirated

75
Inflammatory and Degenerative Conditions

• Tendonitis
• Inflammation of tendon sheaths typically caused
  by overuse
• Symptoms and treatment are similar to bursitis

76
Arthritis

• More than 100 different types of inflammatory or
  degenerative diseases that damage the joints
• Most widespread crippling disease in the U.S.
• Symptoms pain, stiffness, and swelling of a
  joint
• Acute forms are caused by bacteria and are
  treated with antibiotics
• Chronic forms include osteoarthritis, rheumatoid
  arthritis, and gouty arthritis

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Osteoarthritis (OA)

• Most common chronic arthritis often called
  wear-and-tear arthritis
• Affects women more than men
• 85 of all Americans develop OA
• More prevalent in the aged, and is probably
  related to the normal aging process

78
Osteoarthritis Course

• OA reflects the years of abrasion and compression
  causing increased production of metalloproteinase
  enzymes that break down cartilage
• As one ages, cartilage is destroyed more quickly
  than it is replaced
• The exposed bone ends thicken, enlarge, form bone
  spurs, and restrict movement
• Joints most affected are the cervical and lumbar
  spine, fingers, knuckles, knees, and hips

79
Rheumatoid Arthritis (RA)

• Chronic, inflammatory, autoimmune disease of
  unknown cause, with an insidious onset
• Usually arises between the ages of 40 to 50, but
  may occur at any age
• Signs and symptoms include joint tenderness,
  anemia, osteoporosis, muscle atrophy, and
  cardiovascular problems
• The course of RA is marked with exacerbations and
  remissions

80
Rheumatoid Arthritis Course

• RA begins with synovitis of the affected joint
• Inflammatory chemicals are inappropriately
  released
• Inflammatory blood cells migrate to the joint,
  causing swelling

81
Rheumatoid Arthritis Course

• Inflamed synovial membrane thickens into a pannus
• Pannus erodes cartilage, scar tissue forms,
  articulating bone ends connect
• The end result, ankylosis, produces bent,
  deformed fingers

82
Gouty Arthritis

• Deposition of uric acid crystals in joints and
  soft tissues, followed by an inflammation
  response
• Typically, gouty arthritis affects the joint at
  the base of the great toe
• In untreated gouty arthritis, the bone ends fuse
  and immobilize the joint