1. Human Anatomy & Physiology Chapter 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 2

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 3

4. Classification of Joints: Functional Functional classification is based on the amount of movement allowed by the joint The 3 functional class of joints are: Synarthroses – immovable Amphiarthroses – slightly movable Diarthroses – freely movable 4

5. Fibrous Structural Joints The bones are jointed by fibrous tissues There is no joint cavity Most are immovable There are 3 types: sutures, syndesmoses, and gomphoses 5 Figure 8.1a

6. Fibrous Structural Joints: Sutures Occur between the bones of the skull Comprised of interlocking junctions completely filled with short CT fibers Bind bones tightly together, but allow for growth during youth 6

7. Fibrous Structural Joints: Syndesmoses Bones are connected by a fibrous tissue ligament Movement varies from immovable to slightly movable Examples include the connection between the tibia and fibula, and the radius and ulna 7

8. Fibrous Structural Joints Figure 8.1b

9. 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

10. Cartilaginous Joints Articulating bones are united by cartilage Lack a joint cavity Two types – synchondroses & symphyses 10 Figure 8.2a

11. 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

12. Cartilaginous Joints Figure 8.2b

13. 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 13

14. Cartilaginous Joints Figure 8.2c

15. 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 15

16. Synovial Joints: General Structure Synovial joints all have the following: Articular cartilage Joint (synovial) cavity Articular capsule Synovial fluid Reinforcing ligaments 16 Figure 8.3a

17. 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 17

18. Synovial Joints: Friction-Reducing Structures Figure 8.4a, b

19. Synovial Joints: Stability Stability is determined by: Articular surface: shape determines what movements are possible Ligaments – unite bones to prevent excessive or undesirable motion Muscle tone is accomplished by: Muscle tendons across joints are the most important stabilizing factor Tendons kept tight by muscle tone 19

20. 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 20

21. 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 21

22. 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 22

23. Angular Movement Flexion Extension Dorsiflexion and plantar flexion of the foot Abduction Adduction Circumduction 23 Figure 8.5a

24. Angular Movement Flexion: Bending movement that brings bones closer together (decreasing angle of movement) Dorsiflexion of the Foot: drawing the toes posteriorly towards the shin Plantar flexion of the Foot: Pressing foot flat against the ground or pointing toes. Extension: Extends bones away from one another (increasing angle of movement) 24 Figure 8.5a

25. Angular Movement Figure 8.5b

26. Angular Movement Figure 8.5c, d

27. Angular Movements (Cont.) Abduction: Moving away from the midline of the body or spreading the toes and fingers Adduction: Moving towards the midline of the body or closing the fingers and toes Circumduction: Circular cone- shaped movements of the arm or leg 27

28. Angular Movement Figure 8.5e, f

29. Rotation The turning of a bone around its own long axis Examples: Between first two vertebrae Hip and shoulder joints 29 Figure 8.5g

30. Special Movements Supination: Radius and Ulna parallel, palms up or facing anterior Pronation: Radius and Ulna cross in an “X”, palms down or facing posterior 30 Figure 8.6a

31. Special Movements Figure 8.6b

32. Special Movements Inversion: Sole of the foot turns medially (inward) Eversion: Sole of the foot turns laterally (outward) 32 Figure 8.6a

33. Special Movements Figure 8.6b

34. Special Movements Protraction: Jaw pressed forward (protrudes) Retraction: Jaw pulled back (retracted) 34 Figure 8.6a

35. Special Movements Figure 8.6c

36. Special Movements Elevation: Jaw draws upward (biting down?) Depression: Jaw drops down 36 Figure 8.6a

37. Special Movements Figure 8.6d

38. Special Movements Opposition: Movement when two appendages work against one another isometrically (holds objects in place) 38 Figure 8.6a

39. Special Movements Figure 8.6e

40. Types of Synovial Joints Plane joints Articular surfaces are essentially flat Allow only slipping or gliding movements Only examples of nonaxial joints. 40 Figure 8.7a

41. Types of Synovial Joints Hinge joints Projections of one bone fits into a trough-shaped surface on another Motion is along a single plane Uniaxial joints permit flexion-extension only Examples: elbow and interphalangeal joints 41 Figure 8.7b

42. Pivot Joints Rounded end of one bone protrudes into a “sleeve,” or ring, composed of bone or ligaments of another Only uniaxial movement Examples: joint between axis and the dens, and proximal radioulnar joint 42 Figure 8.7c

43. Condyloid, or Ellipsoidal, Joints Oval articular surface of one bone fits into a depression in another Both articular surfaces are oval Biaxial joints permit all angular motions Examples: wrist joints, and knuckle joints 43 Figure 8.7d

44. Saddle Joints Similar to condyloid joints but with greater movement Each articular surface has a concave and a convex surface Example: joint of the thumb 44 Figure 8.7e

45. Ball-and-Socket Joints A spherical 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 45 Figure 8.7f

46. 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 the scapula 46

47. Synovial Joints: Shoulder Stability Weak stability is maintained by: Thin, loose joint capsule Four ligaments 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 47

48. Synovial Joints: Shoulder Stability Figure 8.8a

49. Synovial Joints: Hip Joint Hip (coxal) joint Ball-and-socket joint Head of the femur articulates with the hip socket Good range of motion, but limited by the deep socket and strong ligaments 50

50. Synovial Joints: Hip Stability Figure 8.9a

51. Synovial Joints: Elbow Hinge joint that allows flexion and extension only Radius and ulna articulate with the humerus 53

52. Synovial Joints: Elbow Stability Figure 8.10a

53. Synovial Joints: Knee Largest and most complex joint of the body Allow flexion, extension, and some rotation 56

54. Figure 8.11c Synovial Joints: Major Ligaments and Tendons – Anterior View Tibial (Medial) Collateral Ligament Fibular (lateral) Collateral Ligament 57

55. Anterior cruciate ligament Posterior cruciate ligament Medial meniscus Lateral meniscus 58 Figure 8.11b Synovial Joints: Knee – Other Supporting Structures

56. Sprains The ligaments reinforcing a joint are stretched or torn Partially torn ligaments slowly repair themselves Completely torn ligaments require prompt surgical repair 59

57. Cartilage Injuries The snap and pop of overstressed cartilage Common aerobics injury Repaired with arthroscopic surgery 60

58. 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 61

59. 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 62

60. Inflammatory and Degenerative Conditions Tendonitis Inflammation of tendon sheaths typically caused by overuse Symptoms and treatment are similar to bursitis 63

61. Arthritis More than 100 different types of inflammatory or degenerative diseases that damage the joints Most widespread crippling U.S. disease 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 64

62. 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 65

63. Rheumatoid Arthritis (RA) Chronic, inflammatory, Usually arises between the ages of 40 to 50, but may occur at any age Symptoms include joint tenderness, anemia, osteoporosis, muscle atrophy, and cardiovascular problems 66

64. Developmental Aspects of Joints By embryonic week 8, synovial joints resemble adult joints Few problems occur until late middle age 67

65. Developmental Aspects of Joints Advancing years toll on the joints include: Ligaments and tendons shorten and weaken Intervertebral discs often 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 68