What channels run perpendicular to central canals and connect vessels of periosteum, medullary cavity, and central canal?

• A. Perforating canals
• B. Canaliculi
• C. Lacunae
• D. Central canal

Answer: (A)

Perforating canals are the channels that run perpendicular to the central (Haversian) canals and connect the vascular systems of the periosteum and the medullary cavity with the central canals of adjacent osteons. This arrangement allows blood vessels and nerves to travel deep into the bone, linking the different parts of the osteon network. Canaliculi are tiny passages between lacunae that allow osteocytes to communicate and exchange nutrients locally within an osteon, not to connect vessels between osteons. Lacunae are the spaces housing osteocytes, and the central canal is the main vertical channel inside an osteon containing vessels and nerves, but it does not itself bridge across osteons.