The 'all-or-none' principle in muscle physiology refers to:

Correct Answer: B

Rationale: The 'all-or-none' principle states that a muscle fiber contracts fully or not at all when stimulated above a threshold. It doesn’t contract partially; the strength varies with the number of fibers recruited, not individual fiber response, making 'The idea that muscles can either contract fully or not at all' correct.

Correct Answer: C

Rationale: At joints, cartilage—specifically articular cartilage—covers bone ends, acting as a cushion to absorb shock and reduce friction during movement (e.g., knee cartilage). Ligaments stabilize joints by connecting bones, tendons attach muscles to bones, and muscles move bones, but cartilage directly protects and cushions, making it the correct answer.

Correct Answer: B

Rationale: The diaphysis is the long, cylindrical shaft of a long bone, primarily compact bone, providing strength. The epiphysis is the end, the endosteum lines the interior, and the periosteum (misspelled here as 'periosteium') is the outer membrane, making 'diaphysis' the correct answer.

Correct Answer: C

Rationale: Osteons (or Haversian systems) are the cylindrical units of compact bone, containing lamellae, a central canal, and osteocytes. Lamellae are layers within osteons, canaliculi are channels, and trabeculae are in spongy bone, making 'osteons' the correct answer.

Correct Answer: C

Rationale: Intramembranous ossification forms bone directly from fibrous connective tissue membranes, as in flat skull bones. Hematopoiesis makes blood cells, endochondral ossification uses cartilage, and remodeling reshapes bone, making 'intramembranous ossification' correct.