structure of compact and spongy bone

osteon

functional unit of compact bone

concentric lamellae

layers of bone matrix that surround central canal

lacunae

small cavities between lamellae that house osteocytes

osteocytes

mature bone cells that maintain the matrix

canaliculi

small canals that allow exchange of nutrients, wastes, and gases

central canal

contains blood vessels and run parallel to surface of bone

perforating canal

perpendicular to bone surface. carry blood vessels into deep bone and marrow

circumferential lamellae

lamellae wrapped together around long bone and bind osteons together. involved in bone growth

interstitial lamellae

remnants of osteons that fill in the spaces between osteons

trabeculae

open network formed by the matrix of a type of bone. lacks osteons, capillaries, and venules

red bone marrow

fills spaces between trabeculae. form blood cells and contain blood vessels that supply nutrients to osteocytes via diffusion

yellow bone marrow

stores fat. found in other sites of spongy bone

periosteum

outer fibrous membrane of bones. covers all bone except parts enclosed in joint capsules. fibers are interwoven with tendon fibers

perforating fibers

fibers that become incorporated into bone tissue. increase strength of attachments

functions of periosteum

• isolate bone from surrounding tissues

• provide routes for blood vessels and nerves

• participate in bone growth and repair

endosteum

incomplete inner cellular layer lining the medullary cavity. active during bone growth, repair, and remodeling. contains osteoclasts and osteogenic cells, covers trabeculae of spongy bone, and lines central canal of compact bone