Which term describes channels in bone that contain blood vessels and nerves?

• A. Haversian canal
• B. Endosteum
• C. Epiphysis
• D. Ethmoid bone

Answer: (A)

Blood vessels and nerves travel through the central channels of bone known as Haversian canals. These canals run through each osteon and house a small blood vessel plus a nerve, delivering nutrients and removing wastes to keep bone tissue alive. Each central canal is surrounded by concentric lamellae with tiny spaces called lacunae that hold osteocytes; these osteocytes connect to the canal and to each other via tiny channels called canaliculi, allowing communication and nutrient exchange. Perforating (Volkmann) canals link neighboring Haversian canals to spread blood supply throughout the bone from the outer periosteum inward. The other terms refer to different structures: endosteum is a membrane lining the inner bone surfaces, epiphysis is the end part of a long bone, and the Ethmoid bone is a skull bone, not a channel for vessels and nerves.