Name the two bone types. Describe the structural units of each type. What services are contained within the Haversian canals and canalicules?
There are two bone types: spongy bone and compact bone. Spongy bone is composed of hardened bars arranged in a network with a relatively large amount of space between each bar. Compact bone is composed of hardened structural units, called Haversian systems. These units form an almost continuous mass containing only microscopic interstices, where the bone cells are located. Roughly cylindrical, each Haversian system is made of concentric layers of hard matrix centered around a microscopic passage, called the Haversian canal. The canals contain the nerves and blood vessels that service the bone cells. Even smaller channels, called canalicules, radiate from the canals through the matrix to carry nutrients to the bone cells and wastes away from them back to the blood.
