Which components make up the Haversian system (osteon) in compact bone?

Which components make up the Haversian system (osteon) in compact bone?

• A. A central Haversian canal with blood vessels and nerves, concentric lamellae, lacunae containing osteocytes, and canaliculi.
• B. A system of trabeculae with red marrow and osteoclasts only.
• C. A fibrous capsule around bone with hyaline cartilage.
• D. A single osteon with no vascular supply.

Answer: (A)

The Haversian system, or osteon, is the basic structural unit of compact bone and centers on a central vascular channel. Each osteon has a central Haversian canal that contains blood vessels and nerves, surrounded by concentric rings of mineralized matrix called lamellae. Within these lamellae are lacunae, small spaces that house osteocytes, and these osteocytes connect through tiny channels called canaliculi to enable nutrient and signal exchange. This combination—central canal with vessels, concentric lamellae, lacunae with osteocytes, and canaliculi—defines the osteon’s organization in compact bone. Other descriptions don’t fit this arrangement: trabeculae characterize spongy bone, a joint capsule with hyaline cartilage isn’t the osteon, and a single osteon without a vascular supply would lack the essential central canal.

The Haversian system, or osteon, is the basic structural unit of compact bone and centers on a central vascular channel. Each osteon has a central Haversian canal that contains blood vessels and nerves, surrounded by concentric rings of mineralized matrix called lamellae. Within these lamellae are lacunae, small spaces that house osteocytes, and these osteocytes connect through tiny channels called canaliculi to enable nutrient and signal exchange. This combination—central canal with vessels, concentric lamellae, lacunae with osteocytes, and canaliculi—defines the osteon’s organization in compact bone. Other descriptions don’t fit this arrangement: trabeculae characterize spongy bone, a joint capsule with hyaline cartilage isn’t the osteon, and a single osteon without a vascular supply would lack the essential central canal.