KEY TO OBJECTIVES CHAPTER 8: JOINTS OF THE SKELETAL SYSTEM

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1. Define the term articulation.

A joint (articulation) is the site where two bones come together.

2. Distinguish between the structural and functional classification of joints, and

relate the terms that are essentially synonymous.

Structural Classification Functional Classification

Fibrous

synarthoses

Cartilaginous

amphiarthroses

Synovial

diarthroses

3. Compare and contrast the terms synarthroses, amphiarthroses and diarthroses

and identify the examples of each in the diagrams below.

Functional Classification Definition Example

Synarthroses

Immovable joint Suture (1stdiagram)

Amphiarthroses

Slightly moveable joint Intervertebral disc (2nd diagram)

Diarthroses Freely moveable Elbow, shoulder, hip, and knee (3rd

diagram)

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4. Name the three types of fibrous joints, give an example of each, and identify

each in the diagrams below.

Type of Fibrous Joint Example

Sutures

Coronal suture, etc. (1st diagram)

Syndesmoses

Tibiofibular joint (3rd diagram)

Gomphoses

Periodontal ligaments (2nd diagram)

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5. Identify the two differences between the epiphyseal plate and an intervertebral disc, and identify each in the diagrams below.

Example of Cartilaginous Joint

Difference 1 (hint: Structural classification)

Difference 2 (hint: Functional classification

Epiphyseal Plate (on right) Synchrondrosis Synarthrosis

Intervertebral Disc (bad of fibrocartilage in left diagram)

Symphysis Amphiarthrosis

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6. Label all structures associated with the typical synovial joint below, and provide

the function of each of the labeled structures.

Structure Associated with Synovial Joint Function

Articular cartilage Resists wear and minimizes friction

Joint (articular) capsule Attaches bone to bone; stabilizes joint

Synovial membrane Lines joint cavity and reabsorbs fluid following injury or infection

Synovial fluid

Reduces friction between bones; weeping lubrication

Reinforcing ligaments Reinforce joint capsule; join bone to bone; stabilize/prevent excessive movement by joint

7. Name the components and functions of synovial fluid.

Synovial Fluid Component Function(s) of Synovial Fluid

Water Lubrication and moisturizes cartilage

Phagocytes Phagocytosis

N/A Nourishes cartilage

8. Define the terms fatty pads, articular discs, and bursae, name a key location for

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each, and identify each in the diagram below.

Synovial Joint Feature Definition/description Key location

Fatty pads Pad of adipose tissue that cushions and protects

Hip and knee

Articular Discs (Fibrocartilage)that separates the joint into two compartments (a meniscus)

Knee

Bursae Flattened fibrous sacs with synovial fluid to prevent friction between bone and an adjacent structure

Acromion and skin

9. List and discuss three factors that influence the stability of a synovial joint.

Shape of opposing bone surfaces

Reinforcing ligaments that enclose joint

Muscles that enclose joint

10. Distinguish between the origin and insertion of a muscle, and identify each in the

diagram below.

Origin Insertion

Anchored, immoveable end of a muscle Moveable end of a muscle

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11. Name the three general types of movements allowed by joints.

Gliding angular special

12. List the angular movements allowed by synovial joints, provide a description of

each, and review each movement in the diagrams below.

Angular Movement Description

Flexion Decreasing the angle between two bones

Extension Increasing the angle between two bones

Abduction Moving a bone/body part away from the midline

Adduction Moving a bone/body part toward the midline

Circumduction Moving a limb in a circular motion

Rotation Turning movement of a bone along its long axis

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13. Identify the special movements allowed by the proximal radioulnar joint (i.e. between

radius and ulna), by the sole, by the shoulders, by the jaw, and review each special movement in the diagrams above and below.

Special Movements of Movement 1 Movement 2

Radius/Ulna

supination pronation

Sole

eversion inversion

Shoulders

elevation depression

Jaw

protration retraction

14. Name the six types of synovial joints and provide an example of each.

Type of Synovial Joint Movements Allowed Example

Plane Gliding Intervertebral discs and within carpals

Hinge

Flexion and extension Knee and elbow

Pivot

Rotation First intervertebral disc

Condyloid

All angular movement except rotation Carpals and knuckles

Saddle Concave and convex bone surfaces that allow for free movement

Thumb

Ball-and-socket Head of one bone surface fits into socket of other bone surface permitting all angular movement

Shoulder and hip

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15. Explain how an intervertebral disc can be all of the following: an amphiarthrosis, cartilaginous joint, symphyses, gliding joint, and plane joint.

Intervertebral Disc as How ?

Amphiarthosis

Allows for slight movement

Cartilaginous Joint

Composed of fibrocartilage

Symphyses

Composed of a pad of fibrocartilage

Gliding Joint

Allows for slight movement between body’s of vertebrae

Plane Joint

Allows for gliding movement

16. Name all of the joint classifications that the sutures in the skull, elbows, and hip

joints may satisfy.

Sutures of Skull Elbow Hip

Classifications that each may satisfy

Fibrous Suture Synarthroses

Synovial Diarthrosis Hinge

Synovial Diarthrosis Ball-and-socket

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17. Construct a table comparing the structural and functional classifications of joints, and draw arrows to show the relationships between the two.

18. Discuss some important joint disorders.

Sprains, bursitis, osteoarthritis, rheumatoid arthritis, gout (see pages 271-274)