Narrow tubes within compact bone containing blood vessels and nerves. They generally run parallel to the bone surface. Each canal is surrounded by a series of concentric cylinders of bony matrix (lamellae) containing osteocytes within small cavities (lacunae). Each canal and its lamellae forms a Haversian system, or osteon. Haversian systems are separated from each other by boundaries called glue lines. They are named after the English anatomist Clopton Havers (1657–1702).