Which of the following is an example of a hinge joint?

Correct Answer: D

Rationale: The elbow is a hinge joint, allowing flexion and extension in one plane. The hip and shoulder are ball-and-socket, and the ribcage has slightly movable joints, making 'Elbow' correct.

Correct Answer: B

Rationale: Osteocytes reside in lacunae, small pits in bone matrix (compact or spongy). Haversian canals hold vessels, trabeculae are spongy structures, and endosteum lines cavities—not homes for osteocytes. Answer is B, per the document.

Correct Answer: A

Rationale: A tuberosity is a projection for muscle attachment, not a depression. Facet (flat surface), meatus (tube), and sinus (cavity) are depressions/cavities. Answer is A, per the document.

Correct Answer: A

Rationale: Osteoblasts (bone-forming) and osteoclasts (bone-resorbing) are in the periosteum, the membrane around bones. Lacunae hold osteocytes, not these cells. Answer is A, per the document.

Correct Answer: D

Rationale: Synovial joints are freely movable (diarthrotic) due to synovial fluid, unlike fibrous (immovable), cartilaginous (slightly movable), or amphiarthroses (slightly movable). Answer is D, per the document.