CHAPTER 8: JOINTS OF THE SKELETAL SYSTEM (M

CHAPTER 8: JOINTS OF THE SKELETAL SYSTEM (M.C. FLATH, Ph.D.)

KEY TO OBJECTIVES:

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 (1^stdiagram)*
*Amphiarthroses*	*Slightly moveable joint*	*Intervertebral disc (2^nd diagram)*
*Diarthroses*	*Freely moveable*	*Elbow, shoulder, hip, and knee (3^rd diagram)*

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. (1^st diagram)*
*Syndesmoses*	*Tibiofibular joint (3^rd diagram)*
*Gomphoses*	*Periodontal ligaments (2^nd diagram)*

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 (top right arrow of bottom diagram below)*	*Synchrondrosis*	*Synarthrosis*
*Intervertebral Disc (blue pad of fibrocartilage in b of first diagram)*	*Symphysis*	*Amphiarthrosis*

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*
*Reinfocring 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 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*

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*

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*

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*