Joints of the Skeletal System
2. Define joint .
A joint is a functional junction between bones.
3. Explain how joints ar e classified.
The type of tissue that binds the bones together at each junction can classify joints. They can also be classified according to the degree of movement possible at the bony junctions.
4. Compar e the str uctur e of a fibr ous joint with that of a car tilaginous joint.
A fibr ous joint uses fibrous connective tissue to hold bones together that were in close contact with one another. A car tilaginous joint uses hyaline or fibrocartilage to hold the articulation together.
Neither type allows much movement.
5. Distinguish between a syndesmosis and a sutur e.
A syndesmosis is characterized by bone being bound together by long fibers of connective tissue that form an interosseous ligament. This type of joint has slight movement. A sutur e has a thin layer of fibrous connective tissue that forms the sutural ligament. This type of joint has no movement.
6. Descr ibe a gomphosis, and name an example.
A gomphosis is a joint formed by the union of a cone-shaped bony process in a bony socket. The peglike root of a tooth fastened to a jawbone by a periodontal ligament is such a joint.
7. Compar e the str uctur es of a synchondr osis and a symphysis.
A synchondr osis uses bands of hyaline cartilage to unite to bones. Many of these joints are temporary structures that disappear during growth. This particular type of joint allows no movement. A symphysis has the articular surfaces of bones covered with hyaline cartilage that is attached to a pad of fibrocartilage. This particular type of joint allows a limited type of movement.
8. Explain how the joints between adjacent ver tebr ae per mit movement.
Each of these are symphysis joints. Between each vertebra, there is an inter ver tebr al disk that is composed of a band of fibrocartilage that surrounds a gelatinous core. The disk absorbs shocks and helps equalize pressure between the vertebrae during body movement. As each disk is slightly flexible, the combined movements of many of the joints in the vertebral column allow the back to bend forward, to the side, or to twist.
9. Descr ibe the gener al str uctur e of a synovial joint.
A synovial joint will include the following components:
a. Ar ticular car tilage—Thin layer of hyaline cartilage on the ends of the articulating bones.
b. J oint capsule—Tubular structure that has two distinct layers. The outer layer is made up of dense fibrous connective tissue. The inner layer is a shiny vascular membrane called the synovial membrane. c. Synovial fluid—A clear viscous fluid secreted by the synovial membrane for lubrication of the joint. d. Ligaments—Bundles of tough collagenous fibers that serve to reinforce the joint capsule.
e. Menisci—Disks of fibrocartilage found in some synovial joints that serve as shock absorbers.
f. Bur sae—Fluid-filled sacs that cushion and aid the movement of tendons within a synovial joint.
10. Descr ibe how a joint capsule may be r einfor ced.
Ligaments are used to bind the articular ends of bones together reinforcing the joint capsule. These can be thickenings in the fibrous layer of the joint capsule or accessory structures that are located outside of the joint capsule.
11. Explain the function of the synovial membr ane.
The synovial membr ane covers all surfaces within the joint capsule, except the areas the articular
cartilage covers. It fills spaces and irregularities within the cavity. It secretes synovial fluid. It may store adipose tissue. It also reabsorbs the synovial fluid.
12. Explain the function of synovial fluid
Synovial fluid helps to cushion, moisten, and lubricate the smooth cartilaginous surfaces within the joint. It also supplies the articular cartilage with nutrients.
13. Define meniscus.
A meniscus is a disk of fibrocartilage that occurs in some synovial joints dividing them into two compartments. It serves as a shock absorber and