GLOSSARY

Compact bone, or cortical bone, is the hard, dense outer layer of bone and makes up about 80 percent of skeletal weight.

Structure

The structural unit of compact bone is the osteon, or Haversian system: concentric cylindrical layers of bone matrix called lamellae arranged around a central canal containing vessels and nerves. Bone cells, or osteocytes, lie in small spaces called lacunae between the lamellae and communicate through tiny channels called