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 st diagram) Amphiarthroses Slightly moveable joint Intervertebral disc (2 nd diagram) Diarthroses Freely moveable Elbow, shoulder, hip, and knee (3 rd diagram) 1
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) 2
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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 Difference 1 (hint: Structural Difference 2 (hint: Functional Joint classification) classification Epiphyseal Plate (top right Synchrondrosis Synarthrosis arrow of bottom diagram below) Intervertebral Disc (blue pad of fibrocartilage in b of first diagram) Symphysis Amphiarthrosis 4
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 Hip and knee cushions and protects Articular Discs (Fibrocartilage)that separates Knee the joint into two compartments (a meniscus) Bursae Flattened fibrous sacs with Acromion and skin synovial fluid to prevent friction between bone and an adjacent structure 5
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 6
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 7
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 Thumb for free movement 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 8
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 17. Construct a table comparing the structural and functional classifications of joints, and draw arrows to show the relationships between the two. Structural Classification Functional Classification Fibrous Synarthroses Cartilaginous Amphiarthoses Synovial Diarthroses 18. Discuss some important joint disorders. Sprains, bursitis, osteoarthritis, rheumatoid arthritis, gout (see pages 271-274) 9