Question

which is not a part of all synovial joints?

a. labrum
b. articular cartilage
c. articular capsule
d. synovial membrane

Explanation:

Identify core synovial joint features

Using the Joint Anatomy knowledge point, we recall that all synovial joints share basic structural features. These universal components include an articular capsule, a synovial membrane, a joint cavity containing synovial fluid, and articular cartilage covering the bone surfaces.

Evaluate the given options

• Articular cartilage (B), Articular capsule (C), and Synovial membrane (D) are standard, defining features present in every synovial joint.
• A Labrum (A) is a fibrocartilaginous ring that deepens certain ball-and-socket joints (like the shoulder and hip) but is not found in all synovial joints.

Formulate the final conclusion

Since a labrum is an accessory structure restricted to specific joints, it is not a part of all synovial joints.

Answer:

• A. Labrum (Correct answer)
• B. Articular cartilage
• C. Articular capsule
• D. Synovial membrane