Problem 28 - Anatomy and Physiology of Animals

Question

A cartilaginous joint ________. a. has a joint cavity b. is called a symphysis when the bones are united by fibrocartilage c. anchors the teeth to the jaws d. is formed by a wide sheet of fibrous connective

Step-by-Step Solution

Answer

A cartilaginous joint is called a symphysis when bones are united by fibrocartilage (Option b).

Step 1: Understanding Joint Cavity

A joint cavity is a space that is typically found in synovial joints. Cartilaginous joints do not have a joint cavity. Thus, option (a) is not correct for a cartilaginous joint.

Step 2: Identifying Cartilaginous Joint Types

Cartilaginous joints are mainly of two types: synchondroses and symphyses. In synchondroses, the bones are joined by hyaline cartilage, while in symphyses, they are united by fibrocartilage.

Step 3: Analyzing Symphysis Joint

Symphysis is a type of cartilaginous joint where the bones are connected by fibrocartilage. An example is the pubic symphysis. Thus, option (b) matches this description.

Step 4: Examining Teeth Anchoring

The anchoring of teeth to the jaws is referred to as a gomphosis, which is a type of fibrous joint, not a cartilaginous joint. Therefore, option (c) is incorrect for cartilaginous joints.

Step 5: Evaluating Option of Fibrous Connective

A joint formed by a wide sheet of fibrous connective tissue indicates a fibrous joint, not a cartilaginous joint. This makes option (d) incorrect for describing cartilaginous joints.

Key Concepts

Joint Cavity

In the world of joints, a joint cavity is a significant feature typically associated with synovial joints. It refers to the space between the articulating bones in a joint, which is filled with synovial fluid. This fluid serves several essential functions:

• Lubricating the joint, reducing friction during movement.
• Acting as a shock absorber to protect the joint surfaces.
• Nourishing the cartilage by facilitating the movement of nutrient-rich fluids.

However, when it comes to cartilaginous joints, they stand out because they don't have a joint cavity. Instead, these joints are connected entirely by cartilage - either hyaline or fibrocartilage. This characteristic differentiates them from their synovial counterparts, giving cartilaginous joints unique properties and functions.

Symphysis

Symphyses are a specific type of cartilaginous joint. In these joints, the connecting material is fibrocartilage, which lends both strength and flexibility. The configuration of a symphysis makes it capable of withstanding various forces, especially tension and compression, which occur during regular movement. One of the most well-known examples is the pubic symphysis.
Located at the front of the pelvis, the pubic symphysis plays a critical role in providing stability. It connects the two sides of the pelvis, allowing slight movement, which is crucial during activities like walking or childbirth. Other examples of symphyses include the intervertebral discs, which connect the bones of the spine or vertebrae. By dampening shocks, they protect the spinal column during motion.
Overall, symphyses are crucial components in the framework of our skeletal system, providing a balance of flexibility and strength.

Fibrocartilage

Fibrocartilage is a specialized form of cartilage known for its toughness and ability to handle pressure. It is often found in areas of the body that require a blend of strength and pliability, making it ideal for symphyses and other supportive structures. Unlike other types of cartilage, fibrocartilage contains dense bundles of collagen fibers.

• This density provides fibrocartilage with a robust structure capable of resisting tension and compression.
• The collagen fibers are arranged in a way that enhances the tissue's tensile strength.

Because of its durable nature, fibrocartilage is essential for the function and stability of joints like the pubic symphysis and the intervertebral discs. In addition, it helps maintain the integrity of these structures under mechanical stress, acting as a cushion and a solid anchor point between bones.
Despite its toughness, fibrocartilage maintains some degree of flexibility, essential for the adaptive movements we perform daily.