A&p Chapter 9 - Joints

A point of contact between two bones, between bone and cartilage, or between bone and teeth is referred to as a joint, articulation, or arthrosis. These terms are used interchangeably to describe the location where two or more skeletal elements meet and allow for movement. Joints are crucial for mobility and provide stability to the skeletal system. They can be classified into different types based on their structure and function, such as synovial joints, cartilaginous joints, or fibrous joints.

Osteoarthritis is the most common degenerative joint disease in the elderly, usually caused by wear and tear. It is characterized by the breakdown of cartilage in the joints, leading to pain, stiffness, and reduced range of motion. Unlike rheumatoid arthritis, which is an autoimmune disease, osteoarthritis is not caused by an immune system malfunction. Rheumatism is a general term that refers to any disorder of the joints, muscles, or connective tissues, but it is not specific to degenerative joint diseases. Gouty arthritis is caused by the buildup of uric acid crystals in the joints, and ankylosing spondylitis primarily affects the spine and sacroiliac joints.

Shrugging your shoulders involves elevation and depression, not flexion and extension. Flexion and extension refer to movements that occur in the sagittal plane, such as bending and straightening of a joint. Elevation and depression, on the other hand, refer to movements that occur in the frontal plane, such as raising and lowering the shoulders. Therefore, the statement is false.

Chewing your food involves elevations and depression. When you chew, your mandible (jawbone) moves up and down in a motion called elevation. This allows you to close your mouth and crush the food between your teeth. Additionally, your mandible also moves forward and backward in a motion called depression. This allows you to open your mouth and take bites of food. Therefore, options 4 and 5 (elevations and depression) are the correct choices for this question.

The correct answer is 2, 3, and 5. Structural classifications of joints include cartilaginous, synovial, and fibrous joints. Amphiarthrosis and synarthrosis are functional classifications of joints, not structural classifications.

Arthroplasty is the correct answer because it refers to the surgical procedure of replacing a severely damaged joint with an artificial joint. This procedure is commonly performed to relieve pain and improve mobility in individuals with conditions such as arthritis or joint injuries.

Menisci are not fluid-filled sacs located outside of the joint cavity. Instead, they are crescent-shaped pieces of cartilage that are located inside the joint cavity. Their main function is to provide stability, cushioning, and support to the joint, rather than easing friction between bones and softer tissue. Therefore, the correct answer is False.

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Synovial fluid does not become more viscous as movement at the joint increases. In fact, the opposite is true. Synovial fluid becomes less viscous when movement occurs at the joint. This decrease in viscosity allows for smoother and easier movement of the joint, reducing friction and providing lubrication.

Synovial fluid functions to absorb shocks at joints, lubricate joints, supply oxygen and nutrients to chondrocytes, and provide phagocytes to remove debris from joints.

The correct answer is 1,2,3,4, and 5. The articular surfaces of synovial joints are kept in contact and their range of motion is affected by multiple factors. The structure or shape of the articulating bones plays a role in maintaining contact between the surfaces. The strength and tension of the joint ligaments also contribute to this. The arrangement and tension of muscles surrounding the joint affect its movement. Lack of use can lead to stiffness and decreased range of motion. Finally, the contact of soft parts such as cartilage and synovial fluid also helps in keeping the surfaces in contact.

The correct answer is 2, 3, and 4. This is because statement 2 is true, as the articular capsule does surround a synovial joint and encloses the synovial cavity, uniting the articulating bones. Statement 3 is also true, as the fibrous membrane of the articular capsule allows for considerable movement at a joint. Statement 4 is true as well, as the tensile strength of the fibrous membrane helps prevent bones from disarticulating. Statement 1 is false, as the bones at a synovial joint are not covered by a mucous membrane. Statement 5 is also false, as not all synovial joints contain a fibrous membrane.