ANATOMY

Detailed explanation-1: -Compact bone consists of closely packed osteons or haversian systems. The osteon consists of a central canal called the osteonic (haversian) canal, which is surrounded by concentric rings (lamellae) of matrix. Between the rings of matrix, the bone cells (osteocytes) are located in spaces called lacunae.

Detailed explanation-2: -Compact bone: also known as cortical bone, this hard-outer layer is strong and dense. Cancellous bone: also known as trabecular bone, this spongy inner layer network of trabeculae is lighter and less dense than cortical bone.

Detailed explanation-3: -Osteocytes only exist in cancellous, or spongy bone.

Detailed explanation-4: -In compact bone, osteocytes and intercellular material are organized into osteons that are cemented together. 5. Osteonic canals contain blood vessels and nerve fibers, and extend longitudinally through bone.

Detailed explanation-5: -Osteoblasts in the periosteum form compact bone around the external bone surface. At the same time, osteoclasts in the endosteum break down bone on the internal bone surface, around the medullary cavity.