In which of the following bone structures do osteocytes live?

Correct Answer: C

Rationale: Osteocytes reside in lacunae, small spaces within the lamellae of osteons in compact bone, extending processes into canaliculi for nutrient exchange. Osteons are the units, canaliculi are channels, and lamellae are layers. Answer is C, per the document.

Correct Answer: D

Rationale: Blood vessels in compact bone are in the central (Haversian) canal of osteons, supplying osteocytes via canaliculi. Canaliculi, periosteum, and lacunae don’t house vessels. Answer is D, per the document.

Correct Answer: B

Rationale: The epiphyseal plate (growth plate) is hyaline cartilage between the diaphysis (shaft) and epiphysis (end), ossifying into a line in adults. Answer is B, per the document.

Correct Answer: C

Rationale: Hydroxyapatite, Ca₁₀(PO₄)₆OH₂, is the primary inorganic salt in bone, containing calcium and phosphorus. Others are organic molecules. Answer is C, per the document.

Correct Answer: C

Rationale: The Haversian (central) canal in an osteon contains blood vessels. Canaliculi connect osteocytes, endosteum lines cavities, medullary canal is larger in long bones. Answer is C, per the document.