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Chapter 9: Articulations

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1 Chapter 9: Articulations

2 Articulations Body movement occurs at joints where 2 bones connect
Articulation = joints; site where two or more bones meet

3 Joint Structure Determines direction and distance of movement (range of motion) Joint strength decreases as mobility increases

4 Anatomical/Structural Classification of Joints (based on connecting material
Fibrous: bones joined by fibrous CT with no space Cartilaginous: bones joined by pad or bridge of cartilage Synovial: bones separated by fluid-filled cavity, surrounded by CT

5 Structural Classification
Table 9–2

6 Physiological/Functional Classifications of Joints: (based on the amount of movement)
Synarthrosis: immovable joints - No movement - Fibrous or cartilaginous connections Amphiarthrosis: slightly moveable joint - Little movement Diarthrosis: freely moveable joint - More movement - always synovial connections

7 What common characteristics do typical synarthrotic and amphiarthrotic joints share?
joint capsules filled with fluids non-restricted movement of bony regions bony regions separated by fibrous connective tissue articular cartilages and bursae

8 Synarthroses (Immovable Joints)
Are very strong Edges of bones may touch or interlock 4 Types of Synarthrotic Joints Suture Gomphosis Synchondrosis Synostosis

9 1. Synarthoroses * Immoveable Strength Synotosis: fused bones
- Suture of skull and epiphyseal lines of long bones Suture: interlocked bones, sealed with dense CT - Found only in the skull Gomphosis: tooth in alveolar socket, held by peridontal ligament - Binds teeth to sockets Synchrondrosis: hyaline cartilage bridge between bones - Epiphyseal cartilage of long bones and between vertebrosternal ribs and sternum

10 2. Amphiarthroses * Slightly Moveable, strength with some mobility
Syndesmosis: bones connected by ligament Symphasis: bones separated by pad of fibrocartilage

11 3. Diarthorses = Synovial Joints
Great mobility, less strength and stability At ends of long bones Within articular capsules Lined with synovial membrane

12 Features of Synovial Joints
Articular Cartilage Synovial Cavity Articular Capsule Synovial Fluid Accessory Structures - Meniscus, fat pad, accessory ligaments, tendons, bursa, synovial tendon sheath

13 (a) (b) Synovial ligament Bursa ibia Femur Patella Articular cartilage Fat pad Joint capsule Meniscus Joint cavity Intracapsular ligament Quadriceps tendon Patellar ligament T Marrow cavity Spongy bone Periosteum Synovial membrane Articular capsule Joint cavity (containing synovial fluid) Compact bone

14 1. Articular Cartilages Hyaline cartilage
No perichondrium or periosteum Pad articulating surfaces within articular capsules: prevent bones from touching Smooth surfaces lubricated by synovial fluid: reduce friction

15 Features of Synovial Joints
Synovial cavity: Space between/around opposing bones Has synovial fluid Articular Capsule: 2 layers Outer dense irregular connective tissue, continuous with periosteum Inner synovial membrane (areolar CT), covers inside surface of cavity except articular cartilage, secretes synovial fluid

16 4. Synovial Fluid filtrate from blood plasma + hyaluronic acid from fibroblasts * Functions: 1. Lubrication 2. Nutrient distribution: diffusion medium 3. Shock absorption

17 Synovial Joints: Accessory Structures
Cartilages (Meniscus) Fat pads Ligaments Tendons Bursae Synovial Tendon Sheath

18 Synovial Joints: Accessory Structures
Meniscus: fibrocartilage pad = articular disc Subdivides cavity or changes shape of articular surface, limits range of motion Cushion the joint Fat Pad: Adipose Superficial to joint capsule, Function: protection and space filler

19 Synovial Joints: Accessory Structures
Accessory Ligaments: Dense regular connective tissue Either part of capsule, inside joint, or outside capsule Function: support and strengthen joint Sprain: Ligaments with torn collagen fibers Tendons: Attach muscle to bone Function: Add stability to the joint

20 Synovial Joints: Accessory Structures
Bursa: Synovial fluid filled pocket Function: reduces friction Cushion areas where tendons or ligaments rub Synovial Tendon Sheath: - Tubular bursa around a tendon

21 Synovial Joints: Stabilizing Factors
Prevent injury by limiting range of motion: collagen fibers (joint capsule, ligaments) articulating surfaces and menisci other bones, muscles, or fat pads tendons of articulating bones

22 Functional Classification
Table 9–1

23 synarthrosis; gomphosis symphysis; sutural synchondrosis; synostosis
In a newborn infant, the large bones of the skull are joined by fibrous connective tissue. Which type of joints are these? The bones later grow, interlock, and form immovable joints. Which type of joints are these? synarthrosis; gomphosis symphysis; sutural synchondrosis; synostosis syndesmosis; sutural

24 Why would improper circulation of synovial fluid lead to the degeneration of articular cartilages in the affected joint? Synovial fluid nourishes articular cartilage. Blood flow follows synovial fluid circulation. Articular cartilage is composed of synovial fluid. Both A and B.

25 Joint Injuries Sprain: damage to ligament Bursitis:
Some collagen torn, slow to heal Bursitis: Inflammation of a bursa due to trauma, infection, or repetitive motion ** Synovial joints stabilized by articular capsule and accessory structures to restrict mobility: Increase Mobility = Decrease Stability = Increase chance of dislocation

26 Injuries Luxation: Subluxation: Dislocation Joint Displacement
articulating surfaces forced out of position Joint Displacement Usually damages articular cartilage, ligaments, and joint capsule Pain receptors in all CT of the Joint, except articular cartilage, to prevent actions Subluxation: Partial dislocation Displacement beyond usual anatomical limitation “Double Jointed”

27 The dynamic movements of the skeleton.

28 Movements at Synovial Joints
Linear Movements: Gliding: slight movement in any direction Angular Movements: one plane of motion Flexion: reduce angle in frontal plane Extension: increase angle in frontal place Hyperextension: extension past anatomical position Abduction: move away from longitudinal axis in sagittal plane Adduction: move toward longitudinal axis in Circumduction: move in loop without rotation Rotational Movements: turn on axis Medial Rotation: turn in toward body Lateral Rotation: turn out away from body

29 Linear Motion Pencil maintains vertical orientation, but changes position Figure 9–2a, b

30 Angular Motion Pencil maintains position, but changes orientation
Figure 9–2c

31 Circumduction Circular angular motion Figure 9–2d

32 Rotation Pencil maintains position and orientation, but spins
Figure 9–2e

33 Angular Motion: Flexion
Figure 9–3a

34 Angular Movement: Flexion Vs. Extension
Angular motion Anterior–posterior plane Reduces angle between elements Extension Increases angle between elements

35 Angular Motion: Abduction Vs. Adduction
Figure 9–3b, c

36 Abduction Vs. Adduction
Angular motion Frontal plane Moves away from longitudinal axis Adduction: Moves toward longitudinal axis

37 Circumduction Circular motion without rotation Angular motion
Figure 9–3d

38 Special and Specific Motion
Inversion: turn sole inward Eversion: turn sole outward Dorsiflexion: lift toes Plantar flexion: lift heal Opposition: thumb across palm Pronation: medial rotation of radius Superination: lateral rotation of radius Protraction: move anterior (toward front) Retraction: move posterior (toward back) Elevation: move superior (toward head) Depression: move inferior (toward feet)

39 Inversion and Eversion
Figure 9–5a

40 Dorsiflexion and Plantar Flexion
Figure 9–5b

41 Ranges of Motion Monaxial: movement in 1 plane
Biaxial: movement in 2 planes Triaxial: movement in 3 planes Multiaxial: gliding joints, all directions

42 When you do jumping jacks, which lower limb movements are necessary?
flexion and extension abduction and adduction flexion and abduction plantar flexion and eversion

43 The types of synovial joints, and the relationship of motion to structure.

44 Classification of Synovial Joints by Shape
Gliding Hinge Pivot Ellipsoidal Saddle Ball-and-socket

45 Gliding/Plane Joints Flattened or slightly curved faces
Slide in any direction Figure 9–6 (1 of 6)

46 Hinge Joints Cylindrical projections in trough-shaped surface
Angular motion in a single plane (monaxial) Figure 9–6 (2 of 6)

47 Pivot Joints Round projection in ring shaped depression
Rotation only (monaxial) Figure 9–6 (3 of 6)

48 Ellipsoidal Joints Oval articular facet within an oval depression
Motion in 2 planes (biaxial) Figure 9–6 (4 of 6)

49 Saddle Joints 2 concave faces into convex Straddled (biaxial)
Figure 9–6 (5 of 6)

50 Ball-and-Socket Joints
Spherical head into cup-like socket Round articular face in a depression (triaxial) Figure 9–6 (6 of 6)

51 KEY CONCEPT A joint can’t be both mobile and strong
The greater the mobility, the weaker the joint Mobile joints are supported by muscles and ligaments, not bone-to-bone connections

52 How the vertebrae in the vertebral column articulate.

53 Intervertebral Articulations
Figure 9–7

54 Damage to Intervertebral Discs
Figure 9–8

55 Damage to Intervertebral Discs
Slipped disc: bulge in anulus fibrosus invades vertebral canal Herniated disc: nucleus pulposus breaks through anulus fibrosus presses on spinal cord or nerves

56 Articulations and Movements of the Axial Skeleton
Table 9–3 (1 of 2)

57 Articulations and Movements of the Axial Skeleton
Table 9–3 (2 of 2)

58 The Elbow Joint Figure 9–10

59 The Hip Joint Figure 9–11b, c

60 The Knee Joint Figure 9–12a, b

61 Articulations of the Appendicular Skeleton
Table 9–4 (1 of 2)

62 Articulations of the Appendicular Skeleton
Table 9–4 (2 of 2)

63 The effects of aging on articulations, and the most common clinical problems.

64 Age Related Changes Rheumatism: Arthritis:
Pain and stiffness of skeletal system Arthritis: Rheumatism of synovial joints, caused by damage to articular cartilage Osteoarthritis: - Age 60+, cumulative wear and tear erodes cartilage Rheumatoid Arthritis: - Autoimmune attack, chronic inflammation and damage to joint - Ankylosis: ossification of the joint due to untreated RA Gouty Arthritis: Crystals of uric acid from nucleic acid metabolism form in synovial fluid, damage cartilage Due to metabolic disorders

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