The basic functional unit of compact bone is the osteon, which centers around what structure?

The basic functional unit of compact bone is the osteon, which centers around what structure?

• A. Central canal
• B. Medullary cavity
• C. Periosteum
• D. Lacuna

Answer: (A)

Osteons are organized around a central canal, the Haversian canal, which contains the blood vessels and nerves servicing the bone. The lamellae form concentric rings around this canal, with osteocytes sitting in lacunae between the rings and connected through tiny canaliculi. This central canal is the defining feature around which the osteon centers. The other options don’t fit as the central structure: the medullary cavity is the hollow space inside the bone where marrow sits, the periosteum is the outer protective membrane, and a lacuna is just a small cavity housing an osteocyte, not the central organizing channel of the osteon.

Osteons are organized around a central canal, the Haversian canal, which contains the blood vessels and nerves servicing the bone. The lamellae form concentric rings around this canal, with osteocytes sitting in lacunae between the rings and connected through tiny canaliculi. This central canal is the defining feature around which the osteon centers. The other options don’t fit as the central structure: the medullary cavity is the hollow space inside the bone where marrow sits, the periosteum is the outer protective membrane, and a lacuna is just a small cavity housing an osteocyte, not the central organizing channel of the osteon.