The canaliculi are small channels that link together the lacunae as well as having a function of routing nutrients to osteocytes and expelling waste products. Lacunae are minute spaces that contain bone cells, otherwise known as the osteocytes.
Canaliculi are found in both compact and spongy bone. Compact bones are also many of the human body's larger and long bones, and spongy bone contains bone marrow. In spongy bone, canaliculi are part of the trabeculae, and red bone marrow is located in the spaces between the trabeculae. Spongy bone also allows the osteocytes to receive nourishment from red blood cells.
Compact bone is also known as a Haversian unit, and it contains four parts. These four parts include a Harversian canal, which contains blood and nerves; lamallae which makes bone hard; lacunae; and canaliculi. The bone cells, or osteocytes, do not fill canaliculi completely, and the resulting leftover space is referred to as periosteocytic space. This space will fill up with fluid to help nourish osteocytes. This fluid, known as periosteocytic fluid, contains both calcium and phosphate ions. Canaliculi are important in cartilage types of bone as well as they provide a route by which materials adjacent to the blood vessels are permitted to travel. This materials are then distributed by the canaliculi.