Haversian canals (sometimes canals of Havers, named after British physician Clopton Havers) are a series of microscopic tubes in the outermost region of bone called cortical bone that allow blood vessels and nerves to travel through them. Each haversian canal generally contains one or two capillaries and nerve fibres. The channels are formed by concentric layers called lamellae. The haversian canals surround blood vessels and nerve cells throughout bones and communicate with bone cells (contained in spaces within the dense bone matrix called lacunae) through connections called canaliculi. This unique arrangement is conducive to mineral salt deposits and storage which gives bone tissue its strength.