Bone Anatomy and Ossification Flashcards

Vocabulary flashcards covering long bone anatomy, bone cell types, compact and spongy bone histology, and ossification pathways based on the provided lecture slides.

Diaphysis

The long, main cylindrical shaft portion of a long bone.

Epiphysis

The proximal and distal ends or extremities of a long bone.

Metaphysis

The region in a mature long bone where the diaphysis joins the epiphysis, containing the epiphyseal plate or epiphyseal line.

Epiphyseal Plate

A layer of hyaline cartilage in the metaphysis of a growing bone that allows the diaphysis to grow in length.

Epiphyseal Line

The remnant bony structure formed when cartilage in the epiphyseal plate stops dividing and is replaced by bone tissue.

Articular Cartilage

A thin layer of hyaline cartilage covering the epiphysis where a bone forms a joint with another bone.

Periosteum

A connective tissue membrane covering the bone surface consisting of two layers: an outer fibrous layer of dense irregular connective tissue (D.I.C.T.) and an inner osteogenic layer.

Medullary Cavity

The hollow space within the diaphysis that contains yellow bone marrow in adults.

Endosteum

A thin membrane that lines the medullary cavity of a long bone.

Hemopoiesis

The process of blood cell production, occurring within red bone marrow located in spongy bone.

Osteoprogenitor Cell

Unspecialized stem cell derived from mesenchyme that undergoes mitosis and differentiates into an osteoblast.

Osteoblast

A bone-building cell that synthesizes and deposits bone extracellular matrix (collagen fibers and organic components).

Osteocyte

A mature bone cell that maintains daily bone tissue metabolism and matrix.

Osteoclast

A large cell derived from white blood cell lineage that functions in bone resorption by releasing enzymes and acids to break down bone extracellular matrix.

Calcification

The process where mineral salts, mainly calcium ($\text{Ca}$) and phosphorus ($\text{P}$), crystallize and deposit on collagen fibers in the bone matrix, causing it to harden.

Osteon

The basic structural unit of compact bone (also known as a Haversian system), consisting of concentric lamellae arranged around a central canal.

Concentric Lamellae

Rings of calcified extracellular matrix surrounding the central canal of an osteon.

Haversian Canal

A longitudinal central canal in an osteon containing blood vessels and nerves.

Volkmann's Canal

A transverse or perforating canal that carries blood vessels and nerves from the periosteum into compact bone, connecting central canals and the medullary cavity.

Bone Lacuna

Small spaces located between concentric lamellae containing osteocytes.

Bone Canaliculi

Tiny canals containing extracellular fluid and cytoplasmic processes that connect lacunae with each other and central canals for transport of nutrients and wastes.

Sharpey's Fibers

Perforating collagen fibers that attach the periosteum firmly to underlying compact bone.

Trabeculae

An irregular lattice or network of thin columns of bone tissue found in spongy bone, surrounding spaces filled with red or yellow bone marrow.

Osteoporosis

A condition where bone resorption exceeds bone deposition, resulting in fragile and porous bone structure.

Dual Energy Xray Absorptiometry (DXA or DEXA)

An imaging technique used to measure bone mineral density.

Intra-membranous Ossification

Bone formation occurring directly within fibrous loose connective tissue membranes formed by sheets of mesenchyme, producing flat bones of skull, facial bones, mandible, and clavicle.

Endochondral Ossification

Bone formation where bone tissue replaces a pre-existing hyaline cartilage model, producing long bones such as the femur and humerus.

Interstitial Growth

Growth from within a tissue, such as cartilage model growth in length through cell division of chondrocytes.

Appositional Growth

Growth at the outer surface, leading to an increase in bone or cartilage thickness or width.

Periosteal Bone Collar

A ring of compact bone that develops around the diaphysis of the cartilage model during endochondral ossification.

Periosteal Bud

A collection of blood vessels, osteoblasts, osteoclasts, and bone marrow cells that invades the calcifying central cartilage during endochondral ossification.

Primary Ossification Center

A region in the diaphysis of a long bone where bone tissue first replaces most of the cartilage during endochondral ossification.

Secondary Ossification Center

Regions that develop in the epiphyses of a bone where spongy bone is formed during endochondral ossification.