bone microanatomy

perforating fibers

the connections between muscle, bone and periosteum

osteon

each circular grouping of osteocytes, lamellae, central canal, canaliculi, etc.

central canal

space at the center of an osteon; contains blood vessels

periosteum

external "shrink wrapping" around the diaphysis of bones

endosteum

wrapping inside bones; lines medullary cavity

lacunae

pockets that contain osteocytes

lamellae

layers of matrix (calcium phosphate)

concentric lamellae

layers of matrix arranged in circles (like a target)

canaliculi

small tunnels through which nutrients can pass from blood vessels to lamellae; tiny black lines in image

circumferential lamellae

layers creating the outer edge of compact bone

interstitial lamellae

layers filling in spaces between osteons; not circular

trabeculae of spongy bone

"spokes" of bone tissue; branch out while also creating holes for red bone marrow

epiphyseal line

line of bone tissue that has "closed"... composed of bone, not cartilage. growth at this stage has stopped

epiphyseal plate

Growth plate, made of cartilage, gradually ossifies; (letter c in the image)

perforating canals

Perpendicular to the central canal

Carry blood vessels into bone and marrow

Epiphyses

proximal and distal ends of the bone; long bone

Epiphyseal Plate

Growth plate, made of cartilage, gradually ossifies

articular cartilage

covers the surfaces of bones where they come together to form joints

Medullary Cavity

The marrow cavity in the shaft of a long bone.

Lacuna

chambers containing osteocytes

Lamella

Concentric matrix of collagen and calcium

Canaliculi

Connect lacuna together so bone cells can communicate with each other.

perforating canal

Connect blood vessels and nerve supply and run transversely

Osteoprogenitor/ osteogenic

can undergo mitosis and become osteoblasts

Osteoblasts

cannot undergo mitosis, build bone

Osteocytes

also cannot undergo mitosis, maintain daily cellular activities

Osteoclasts

bone resorption, clear away bone matrix

Endosteum

lines the medullary cavity

periosteum

A dense fibrous membrane covering the surface of bones (except at their extremities) and serving as an attachment for tendons and muscles.

Trebeculae

thin strands of bone within spongy bone

Diaphysis

shaft of a long bone

Haversian canals

major passageways running in the direction of the length of long bones, providing paths for blood vessels

osteon

functional unit of compact bone

metaphysis

growth zone between the epiphysis and the diaphysis during development of a long bone

ossification

process of bone formation, osteoblasts replace cartilage framework with new bone

Bone remodeling

ongoing replacement of old bone tissue by new bone tissue