What is the primary function of the ribs in the axial skeleton?

Correct Answer: D

Rationale: The ribs, part of the axial skeleton’s thoracic cage, primarily protect thoracic organs like the heart and lungs by forming a bony enclosure. They don’t support lower limbs, protect the spinal cord (vertebral column’s role), or aid digestion, making 'Protecting the thoracic organs' correct.

Correct Answer: B

Rationale: Tendons are tough, fibrous connective tissues that attach skeletal muscles to bones, transmitting force to enable movement (e.g., Achilles tendon). Ligaments connect bones to bones, cartilage cushions joints, and joints are bone meeting points, not attachments, making 'tendons' the correct answer.

Correct Answer: C

Rationale: The epiphysis is the end of a long bone, containing spongy bone and red marrow, articulating with other bones. The diaphysis is the shaft, the endosteum lines the medullary cavity, and the periosteum covers the exterior, making 'epiphysis' the correct answer.

Correct Answer: A

Rationale: Lamellae are the concentric rings of bone matrix surrounding the central canal in osteons of compact bone, providing strength. Lacunae house osteocytes, canaliculi connect them, and the endosteum lines the interior, making 'lamellae' correct.

Correct Answer: D

Rationale: Osteoclasts are specialized cells that resorb or break down bone tissue, aiding in remodeling and calcium release. Osteoprogenitor cells are stem cells, osteoblasts build bone, and osteocytes maintain it, making 'osteoclasts' correct.