1. Human Anatomy & Physiology, Sixth Edition 8 Joints

2. Classification of Joints:  Articulation  site where two or more bones meet  Structural classification  Criteria: tissues connecting bones; presence of a joint cavity  Fibrous  Cartilaginous  Synovial  Functional classification  Criteria: degree of movement  Synarthrotic – immovable  Amphiarthrotic – slightly movable  Diarthrotic – freely movable

3. Fibrous Structural Joints:  Sutures  interlocking junctions between the bones of the skull  allow for growth  form synostoses  Syndesmoses  immovable or slightly movable ligament connections  e.g. between tibia & fibula, and radius & ulna  Fibrous connective tissues joining bones, no joint cavity, synarthrotic

4. Cartilaginous Joints:  Synchondroses  hyaline cartilage between bones  synarthrotic, but cartilage itself can flex  e.g. between ribs & the sternum  Symphyses  Hyaline cartilage of articulating surface fused to fibrocartilage pad  Amphiarthrotic joints  e.g. intervertebral joints & pubic symphysis

5. Synovial Joints  Articular cartilage forming the articular capsule  Synovial cavity filled with synovial fluid  Surrounded by reinforcing ligaments  Diarthrotic  all limb joints

6. Synovial Joints: General Structure Figure 8.3a, b

7. Synovial Joints: Friction-Reducing Structures  Bursae – fibrous sacs containing synovial fluid  Common where ligaments, muscles, tendons, or bones rub together  Tendon sheath – elongated bursa that wraps completely around a tendon

8. Synovial Joints: Stability  Stability is determined by:  Articular surfaces – shape determines what movements are possible  Ligaments – unite bones and prevent excessive or undesirable motion  Tendons kept tight by muscle tone

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

10. 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

11. 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

12. Gliding Movement Figure 8.5a

13. Angular Movement  Flexion — decreases the angle of the joint  Extension — reverse of flexion; joint angle is increased  Abduction — movement away from the midline  Adduction — movement toward the midline  Circumduction — movement traces a cone in space

14. Angular Movement Figure 8.5b

15. Angular Movement Figure 8.5c, d

16. Angular Movement Figure 8.5e, f

17. Rotation  The turning of a bone around its own long axis  Examples  Between first two vertebrae  Hip and shoulder joints Figure 8.5g

18. Types of Synovial Joints - Plane joints  Articular surfaces are essentially flat  Allow gliding movements Figure 8.7a

19. Types of Synovial Joints- Hinge joints  Cylindrical projections of one bone fits into a trough-shaped surface on another  Uniaxial - Motion in a single plane - flexion and extension only  e.g.: elbow and phalangeal joints

20. Pivot Joints  Rounded end of one bone protrudes into a ligament or bone sleeve  Uniaxial movement allowed  e.g. joint between the dens of axis & the atlas; proximal radioulnar joint

21. Condyloid, or Ellipsoidal, Joints  Oval surface of one bone fits depression in another  Biaxial joints permit all angular motions  e.g. radiocarpal (wrist) joints, and metacarpophalangeal joints

22. Saddle Joints  Similar to condyloid joints  Each articular surface has both a concave and a convex surface  e.g. carpometacarpal joint of the thumb

23. Ball-and-Socket Joints  A spherical or hemispherical head of one bone articulates with a cuplike socket of another  Multiaxial joints are the most freely moving synovial joints  e.g. shoulder & hip

24. 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  Lateral and medial tibiofemoral joints

25.  Tendon of the quadriceps femoris muscle  Lateral and medial patellar retinacula  Fibular and tibial collateral ligaments  Patellar ligament Synovial Joints: Knee Ligaments and Tendons – Figure 8.8c

26. Figure 8.8b Synovial Joints: Knee - Anterior View

27.  Adductor magnus tendon  Articular capsule  Oblique popliteal ligament  Arcuate popliteal ligament  Semimembranosus tendon Figure 8.8e Synovial Joints: Knee – Posterior View

28. 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  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

29. Synovial Joints: Shoulder Stability Figure 8.10a

30. 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

31.  Acetabular labrum  Iliofemoral ligament  Pubofemoral ligament  Ischiofemoral ligament  Ligamentum teres Figure 8.11a Synovial Joints: Hip Stability

32. Synovial Joints: Elbow  Hinge joint that allows flexion and extension only  Radius and ulna articulate with the humerus

33. Figure 8.12b, d Synovial Joints: Elbow Stability  Annular ligament  Ulnar collateral ligament  Radial collateral ligament

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

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

36. 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

37. 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

38. 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

39. 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

40. 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

41. Osteoarthritis: Treatments  OA is slow and irreversible  Treatments include:  Mild pain relievers, along with moderate activity  Glucosamine sulfate decreases pain and inflammation

42. 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

43. 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  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

44. Rheumatoid Arthritis: Treatment  Conservative therapy – aspirin, long-term use of antibiotics, and physical therapy  Progressive treatment – anti-inflammatory drugs or immunosuppressants  The drug Enbrel, a response modifier, neutralizes the harmful properties of inflammatory chemicals