What is the fundamental cylindrical unit of dense or compact bone?

What is the fundamental cylindrical unit of dense or compact bone?

• A. Lamellae
• B. Canaliculi
• C. Osteon
• D. Trabeculae

Answer: (C)

Dense bone is organized into osteons, the cylindrical units that give this tissue its strength. Each osteon centers on a Haversian canal that houses blood vessels and nerves, and is wrapped by concentric rings of mineralized bone called lamellae. Between these lamellae lie lacunae with osteocytes, and tiny channels called canaliculi connect the osteocytes to one another and to the central canal, enabling nutrient and waste exchange. This precise, repeating cylindrical arrangement is what makes compact bone both strong and capable of remodeling. The other structures—lamellae are the rings themselves, canaliculi are the tiny communication pathways, and trabeculae are the lattice-like elements of cancellous bone—are parts of the overall bone anatomy but not the cylindrical unit of dense bone.

Dense bone is organized into osteons, the cylindrical units that give this tissue its strength. Each osteon centers on a Haversian canal that houses blood vessels and nerves, and is wrapped by concentric rings of mineralized bone called lamellae. Between these lamellae lie lacunae with osteocytes, and tiny channels called canaliculi connect the osteocytes to one another and to the central canal, enabling nutrient and waste exchange. This precise, repeating cylindrical arrangement is what makes compact bone both strong and capable of remodeling. The other structures—lamellae are the rings themselves, canaliculi are the tiny communication pathways, and trabeculae are the lattice-like elements of cancellous bone—are parts of the overall bone anatomy but not the cylindrical unit of dense bone.