Joints

1. Part 5 Joints

2. Selected Synovial Joints • Shoulder (Glenohumeral) joint • The most freely movable joint lacks stability • Articular capsule is thin and loose • Muscle tendons contribute to joint stability

3. Glenohumeral Joint Figure 9.8a

4. Glenohumeral Joint • The rotator cuff is made up of four muscles and their associated tendons • Subscapularis • Supraspinatus • Infraspinatus • Teres minor • Rotator cuff injuries are common shoulder injuries

5. The shoulder joint Figure 9.8b, c

6. The Shoulder Joint Figure 9.8d, e

7. Selected Synovial Joints • Elbow joint • Allows flexion and extension • The humerus’ articulation with the trochlear notch of the ulna forms the hinge • Tendons of biceps and triceps brachii provide stability

8. Elbow Joint Figure 9.9a, b

9. Elbow Joint Figure 9.9c, d

10. Wrist Joint • Stabilized by numerous ligaments • Composed of radiocarpal and intercarpal joint • Radiocarpal joint – joint between the radius and proximal carpals (the scaphoid and lunate) • Allows for flexion, extension, adduction, abduction, and circumduction • Intercarpal joint – joint between the proximal and distal rows or carpals • Allows for gliding movement

11. Wrist Joint Figure 9.10a

12. Wrist Joint Figure 9.10b

13. Wrist Joint Figure 9.10c

14. Selected Synovial Joints • Hip joint • A ball-and-socket structure • Movements occur in all axes • Limited by ligaments and acetabulum • Head of femur articulates with acetabulum • Stability comes chiefly from acetabulum and capsular ligaments • Muscle tendons contribute somewhat to stability PLAY Movement at the hip joint: An overview

15. Frontal Section and Anterior View of the Hip Joint Figure 9.11a, b

16. Posterior View of the Hip Joint Figure 9.11c, d

17. Selected Synovial Joints • Knee joint • The largest and most complex joint • Primarily acts as a hinge joint • Has some capacity for rotation when leg is flexed • Structurally considered compound and bicondyloid • Two fibrocartilage menisci occur within the joint cavity

18. Sagittal Section and Superior View of Knee Joint Figure 9.12a

19. Sagittal Section and Superior View of Knee Joint Figure 9.12b

20. Knee Joint • Capsule of knee joint • Covers posterior and lateral aspects of the knee • Covers tibial and femoral condyles • Does not cover the anterior aspect of the knee • Anteriorly covered by three ligaments • Patellar, medial, and lateral retinacula

21. Anterior View of Knee Figure 9.12c

22. Knee Joint • Ligaments of the knee joint • Become taut when knee is extended • These extracapsular ligaments are • Fibular and tibial collateral ligament • Oblique popliteal ligament • Arcuate popliteal ligament

23. Posterior View of Knee Joint Figure 9.12d

24. Knee Joint • Intracapsular ligaments • Cruciate ligaments • Cross each other like an “X” • Each cruciate ligament runs from the proximal tibia to the distal femur • Anterior cruciate ligament • Posterior cruciate ligament

25. Anterior View of Flexed Knee Figure 9.12e, f

26. Knee Joint • Cruciate ligaments • Prevent undesirable movements at the knee joint Figure 9.13a

27. Selected Synovial Joint • Ankle Joint • A hinge joint between • United inferior ends of tibia and fibula • The talus of the foot • Allows the movements • Dorsiflexion and plantar flexion only

28. The Ankle Joint • Medially and laterally stabilized by ligaments • Medial (deltoid) ligament • Lateral ligament • Inferior ends of tibia and fibula are joined by ligaments • Anterior and posterior tibiofibular ligaments

29. The Ankle Joint Figure 9.15a

30. Ligaments of the Ankle Joint Figure 9.15b

31. Ligaments of the Ankle Joint Figure 9.15c

32. Ligaments of the Ankle Joint Figure 9.15d

33. Selected Synovial Joints • Temporomandibular joint (TMJ) • Lies anterior to the ear • Head of the mandible articulates with the mandibular fossa • Two surfaces of the articular disc allow two kinds of movement • Hinge-like movement • Superior surface of disc glides anteriorly

34. The Temporomandibular Joint Figure 9.16a, b

35. Selected Synovial Joints • Sternoclavicular Joint • Is a saddle joint • Muscles and ligaments contribute to joint stability • Unique joint shape allows for multiple complex movements • Another example of a saddle joint • Joint between trapezium and metacarpal 1

36. Sternoclavicular Joint Figure 9.17a

37. Sternoclavicular Joint Figure 9.17b

38. Disorders of Joints • Structure of joints makes them prone to traumatic stress • Function of joints makes them subject to friction and wear • Affected by inflammatory and degenerative processes

39. Joint Injuries • Sprains – ligaments of a reinforcing joint are stretched or torn • Dislocation – occurs when the bones of a joint are forced out of alignment • Torn cartilage – common injury to meniscus of knee joint

40. Inflammatory and Degenerative Conditions • Bursitis – inflammation of a bursa do to injury or friction • Tendonitis – inflammation of a tendon sheath

41. Inflammatory and Degenerative Conditions • Arthritis – describes over 100 kinds of joint-damaging diseases • Osteoarthritis – most common type “wear and tear” arthritis • Rheumatoid arthritis – a chronic inflammatory disorder • Gouty arthritis (gout) – uric acid build-up causes pain in joints • Lyme disease – inflammatory disease often resulting in joint pain

42. The Joints Throughout Life • Synovial joints develop from mesenchyme • By week 8 of fetal development, joints resemble adult joints • Outer region of mesenchyme becomes fibrous joint capsule • Inner region becomes the joint cavity

43. The Joints Throughout Life • During youth – injury may tear an epiphysis off a bone shaft • Advancing age – osteoarthritis becomes more common • Exercise – helps maintain joint health