Articulations (Joints)

1. Articulations (Joints) Martini Chapter 9 Bio 103 Feb 11, 2008

2. Joint Classifications Functional Classification based on range of motion Anatomical (structural) Classification based on material in joint

3. Structural vs. Functional Joint Classifications structural categories do have some relationship with the functional categories (structure  function)

4. Structural Joint Categories • Fibrous • no joint cavity • held together with fibrous connective tissue

5. Structural Joint Categories • Fibrous • no joint cavity • held together with fibrous connective tissue • Cartilaginous • no joint cavity • held together with cartilage

6. Structural Joint Categories • Fibrous • no joint cavity • held together with fibrous connective tissue • Cartilaginous • no joint cavity • held together with cartilage • Synovial • has a joint cavity • articular capsule and ligaments join bones

7. Functional Joint Classification

8. 3 Functional Classifications Synarthrosis (together + joint) no movement structural type: fibrous, cartilaginous, or bony fusion

9. 4 Types of Synarthrotic Joints Suture (sewn together) fibrous bound by dense fibrous connective tissue found only in skull

10. 4 Types of Synarthrotic Joints Gomphosis (bolted together) fibrous binds teeth to bony sockets (maxillary bone and mandible) fibrous connection between tooth and socket is called periodontal ligament

11. 4 Types of Synarthrotic Joints Synchondrosis (together + cartilage) cartilaginous rigid bridge between 2 bones epiphyseal cartilage of long bones Between ribs and sternum

12. 4 Types of Synarthrotic Joints Synostosis totally rigid fused bones (bony fusion) epiphyseal lines of mature long bones metopic suture in frontal bone (doesn’t always fuse!)

13. Craniosynostosis • when skull sutures fuse prematurely

14. 3 Functional Classifications Amphiarthrosis (both sides + joint) little movement structural type: fibrous or cartilaginous

15. 2 Types of Amphiarthroses Syndesmosis (desmos = ligament) bones connected by ligaments example between tibia and fibula

16. 2 Types of Amphiarthroses Symphysis bones separated by a wedge or pad of fibrocartilage intervertebral discs connection between pubic bones

17. 3 Functional Classifications Diarthrosis (through + joint) more movement articular cartilage + synovial fluid + accessory structures

18. Diarthrosis (Synovial) Joints freely moveable joints catagorized by movement type typically located in appendicular skeleton, at connections of long bones The shoulder joint is the most freely moving joint in the body.

19. Synovial Joint Structure articular capsule unites 2 bone ends

20. Synovial Joint Structure articular capsule unites 2 bone ends outer layer fibrous, dense irregular connective tissue that blends with the periostea of the two bones to form ligaments

21. Synovial Joint Structure articular capsule unites 2 bone ends outer layer fibrous, dense irregular connective tissue that blends with the periostea of the two bones to form ligaments inner layer (synovial membrane) composed of areolar tissue and epithelial tissue

22. Synovial Joint Structure articular cartilage like hyaline cartilage, but no perichondrium matrix more watery

23. Synovial Joint Structure synovial fluid thin film between articular cartilage creates smooth gliding surface

24. Synovial Joint Structure synovial fluid thin film between articular cartilage creates smooth gliding surface similar to interstitial fluid with high concentration of proteoglycans consistency of molasses

25. Functions of Synovial fluid Lubrication cartilage sucks up fluid like sponge and releases when compressed to reduce friction

26. Functions of Synovial fluid Lubrication cartilage sucks up fluid like sponge and releases when compressed to reduce friction Nutrient Distribution fluid circulates bringing nutrients and removing wastes for chondrocytes

27. Functions of Synovial fluid Lubrication cartilage sucks up fluid like sponge and releases when compressed to reduce friction Nutrient Distribution fluid circulates bringing nutrients and removing wastes for chondrocytes Shock absorption lessens shock by distributing pressure evenly across articular surface

28. Synovial Joint Accessory Structures Cartilages meniscus(crescent) aka articular disc pad of fibrocartilage that sits between 2 bones

29. Synovial Joint Accessory Structures Fat pads covered by synovial membrane protect articular cartilages act as packing material for joint, filling in spaces left as joint cavity changes shape

30. Synovial Joint Accessory Structures Ligaments attach bone to bone support and strengthen joints

31. Synovial Joint Accessory Structures Ligaments Intrinsic (capsular) ligaments thickening of joint capsule

32. Synovial Joint Accessory Structures Ligaments Extrinsic ligaments separate from joint capsule intracapsular (inside capsule) e.g., ACL, PCL extracapsular (outside capsule) patellar ligament

33. Sprains • ligament collagen stretched/torn • more likely to break bone than tear ligament

34. Synovial Joint Accessory Structures Tendons attach to muscles around joint, but not a part of articulation pass through/around joint and can affect joint movement

35. Synovial Joint Accessory Structures Bursae(pouch) pockets of synovial fluid that cushion areas where tendons or ligaments rub against other tissue synovial tendon sheaths tubular bursae that surround tendons where they cross bone

36. Bursitis • inflammation of bursae causing pain during motion • caused by: • overuse • pressure • bunion • chemicals/infection

37. Stabilization of Joints • movement beyond range causes joint damage

38. Stabilization of Joints • movement beyond range causes joint damage • greater range of motion = greater chance for injury

39. Stabilization of Joints • movement beyond range causes joint damage • greater range of motion = greater chance for injury • To reduce chance of injury joints are stabilized by:

40. Stabilization of Joints • movement beyond range causes joint damage • greater range of motion = greater chance for injury • To reduce chance of injury joints are stabilized by: • collagen fibers of capsule and ligaments • shape of articulating surfaces and menisci might prevent movement in certain directions • presence of other bones, muscles, fat pads around joint • tension in tendons encourages movement in specific direction

41. Describing Dynamic Motion 3 possible movements 1. linear (gliding) 2. angular (circumduction) 3. rotation

42. Types of Movements at Synovial Joints

43. Types of Movements at Synovial Joints Linear Motion (Gliding) 2 opposing surfaces slide past one another between carpal bones clavicle and sternum between tarsal bones

44. Types of Movements at Synovial Joints Flexion/Extension movement in anterior/posterior plane flexion reduces the angle extension increases the angle in the anatomical position, all major joints (except ankle) are at full extension. extension past the anatomical position is called hyperextension example is bending your neck backwards to look at the sky

45. Types of Movements at Synovial Joints Abduction/Adduction angular movement in frontal plane abduction moves away from the longitudinal axis of the body adduction moving towards the longitudinal axis of the body

46. Types of Movements at Synovial Joints Circumduction angular motion, without rotation

47. Types of Movements at Synovial Joints Rotation Left or right rotation Medial rotation (inward rotation) rotates toward axis Lateral rotation (outward rotation) rotates away from axis

48. Types of Movements at Synovial Joints Rotation of the forearm Pronation: rotates forearm, radius over ulna Supination: forearm in anatomical position

49. Special Movements Inversion/Eversion twisting motion of the foot that turns sole inward (inversion) or outward (eversion)

50. Special Movements Dorsiflexion/Plantar flexion flexion at ankle joint dorsiflexion elevates sole plantar flexion elevates heel NOTE: it is acceptable to use the terms flexion and extension for these movements of the ankle.