1. Ch 8
Joints

2. Joints (Articulations)
Weakest parts of the skeleton
 Articulation – site where two or more bones meet
Functions
    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 class of joints are:
    Synarthroses – immovable
    Amphiarthroses – slightly movable
    Diarthroses – freely movable

5. Fibrous Structural Joints
The bones are jointed by fibrous tissues
There is no joint cavity
Most are immovable
There are three types:
Sutures
Syndesmoses
Gomphoses

6. Fibrous Structural Joints: Sutures
Occur between the bones of the skull
Comprised of interlocking junctions completely filled with CT 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: 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

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

9. Cartilaginous Joints Articulating bones are united by cartilage
Lack a joint cavity
Two types – synchondroses and symphyses

10. 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

11. 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

12. 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

13. Synovial Joints: General Structure
Synovial joints all have the following:
    Articular cartilage
    Joint (synovial) cavity
    Articular capsule
    Synovial fluid
    Reinforcing ligaments

15. 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

16. Synovial Joints: Stability
Stability is determined by:
    Articular surfaces – shape determines what movements are possible
    Ligaments – unite bones and prevent excessive or undesirable motion
Muscle tone is accomplished by:
    Muscle tendons across joints are the most important stabilizing factor
    Tendons are kept tight at all times by muscle tone

17. Synovial Joints: Movement
Muscle attachment across a joint
Origin – attachment to the immovable bone
Insertion – attachment to the movable bone
Described as movement along transverse, frontal, or sagittal planes

18. 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

19. 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

20. Angular Movement Flexion Extension
Dorsiflexion and plantar flexion of the foot
Abduction
Adduction
Circumduction

21. Rotation The turning of a bone around its own long axis Examples:
    Between first two vertebrae
    Hip and shoulder joints

22. Special Movements Supination and pronation Inversion and eversion
Protraction and retraction
Elevation and depression
Opposition

23. Types of Synovial Joints
Plane joints
    Articular surfaces are essentially flat
    Allow only slipping or gliding movements
    Only examples of nonaxial 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

24. 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

25. Pivot Joints

26. 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

27. Saddle Joints Similar to condyloid joints but with greater movement
Each articular surface has both a concave and a convex surface
Example: carpometacarpal joint of the thumb

28. 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

29. 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

31. 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) encircles the shoulder joint and blends with the articular capsule

32. Synovial Joints: Knee Largest and most complex joint of the body
Allow flexion, extension, and some rotation
Three joints in one surrounded by a single joint cavity
    Femoropatellar
    Lateral and medial tibiofemoral joints

33. Types of Joints

34. Synovial Joints: Major Ligaments and Tendons – Anterior View
Tendon of the quadriceps femoris muscle
Lateral and medial patellar retinacula
Fibular collateral ligament
Tibial collateral ligament
Patellar ligament

35. Synovial Joints: Knee – Other Supporting Structures
Anterior cruciate ligament
Posterior cruciate ligament
Medial meniscus (semilunar cartilage)
Lateral meniscus

36. Synovial Joints: Knee – Posterior Superficial View
Adductor magnus tendon
Articular capsule
Oblique popliteal ligament
Arcuate popliteal ligament
Semimembranosus tendon

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

38. Sprain

39. Cartilage Injuries The snap and pop of overstressed cartilage
Common aerobics injury
Repaired with arthroscopic surgery

40. Cartilage Injuries

41. 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

42. Dislocation

43. Dislocation

44. 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
      Tendonitis
    Inflammation of tendon sheaths typically caused by overuse
    Symptoms and treatment are similar to bursitis

45. 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

46. 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

48. 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

50. Osteoarthritis: Treatments
OA is slow and irreversible
Treatments include:
    Mild pain relievers, along with moderate activity
    Magnetic therapy
    Glucosamine sulfate decreases pain and inflammation
    SAM-e (s-adenosylmethionine) builds up cartilage matrix and regenerates tissue

51. 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

52. Rheumatoid Arthritis: Course
RA begins with synovitis of the affected joint
Inflammatory blood cells migrate to the joint, causing swelling
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

53. Rheumatoid Arthritis: Treatment
Conservative therapy – aspirin, long-term use of antibiotics, and physical therapy
Progressive treatment – anti-inflammatory drugs or immunosuppressants
The drug Embrel, a biological response modifier, removes cells that promote inflammation

54. 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
Treatment – colchicine, nonsteroidal anti-inflammatory drugs, and glucocorticoids

55. Developmental Aspects of Joints
By embryonic week 8, synovial joints resemble adult joints
Few problems occur until late middle age
Advancing years take their toll on joints including:
Ligaments and tendons shorten and weaken
Intervertebral discs become more likely to herniate
OA is inevitable, and all people of 70 have some degree of OA
Prudent exercise (especially swimming) that coaxes joints through their full range of motion is key to postponing joint problems