The Skeletal System Vocabulary

Vocabulary flashcards covering the anatomical components, cell types, tissues, structures, and developmental processes of the skeletal system.

Red Bone Marrow

A type of connective tissue located in spongy bone that stores stem cells responsible for generating blood cells and platelets.

Yellow Bone Marrow

Adipose tissue housed within the medullary cavity of long bone shafts that serves as an energy reserve of last resort.

Ligaments

Structures composed of dense regular connective tissue that connect two bones together.

Dense Regular Connective Tissue

Connective tissue consisting of fibroblasts and collagen fibers aligned parallel in one direction, allowing pull in a single direction.

Hyaline Cartilage

Cartilage providing firm but flexible support, made of chondrocytes in lacunae and a thick gelatinous extracellular matrix with thin non-visible collagen fibers.

Fibrocartilage

Cartilage designed to resist compression and distortion to increase support, containing chondrocytes in lacunae and thick collagen fibers.

Elastic Cartilage

Cartilage that provides flexible and elastic support allowing distortion and recoil, containing chondrocytes in lacunae and elastic fibers.

Osteocytes

Mature bone cells stuck within lacunae and surrounded by calcified extracellular matrix that maintain the bone matrix.

Osteogenic Cells

Stem cells located on the outer edges of bones that divide and differentiate into osteoblasts.

Osteoblasts

Bone-building cells located on outer edges of bones that create new bone extracellular matrix, including minerals and collagen.

Osteoclasts

Multinucleated cells derived from white blood cells that crush and digest bone extracellular matrix for remodeling.

Osteoid (Bone Matrix)

The extracellular matrix of bone composed of calcium and phosphorus salt crystals for compression strength/hardness, and collagen fibers for flexibility and twisting resistance.

Osteogenesis Imperfecta

A genetic disorder characterized by improperly formed collagen, causing bones to become extremely brittle and shatter easily.

Rickets

A condition in which bones lack sufficient minerals (calcium), causing them to bend easily under body weight.

Compact Bone

Dense, solid bone tissue located on the superficial aspect of all bones that provides rigid structural support.

Osteon

The elongated cylindrical structural unit of compact bone containing a central canal for blood vessels/nerves, lamellae rings, and osteocytes in lacunae.

Spongy Bone

Deep bone tissue composed of a honeycomb network of trabeculae that reduces bone weight and houses red bone marrow.

Trabeculae

Elongated irregular cylinders of bone in spongy bone surrounded by endosteum, containing lamellae and osteocytes without a central canal.

Periosteum

A connective tissue layer covering the outer surface perimeter of a bone that harbors osteogenic cells and osteoblasts.

Endosteum

A connective tissue layer lining the internal medullary cavity and covering the trabeculae of spongy bone.

Diaphysis

The long, narrow shaft forming the middle section of a long bone.

Medullary Cavity

The hollow center within the diaphysis of long bones, filled with yellow bone marrow in adults and red bone marrow in children.

Epiphysis

The expanded rounded end of a long bone, filled with spongy bone and covered by compact bone and articular cartilage.

Epiphyseal Plate

A hyaline cartilage region in children's long bones between the diaphysis and epiphysis where longitudinal bone growth occurs.

Epiphyseal Line

The bony line remaining between the diaphysis and epiphysis of adult long bones after epiphyseal plate closure.

Axial Skeleton

The central skeleton division consisting of the skull, ribs, sternum, and vertebrae that protects vital organs.

Appendicular Skeleton

The skeletal division comprising the upper and lower limb bones along with the pectoral and pelvic girdles.

Endochondral Ossification

The process of bone formation in which a hyaline cartilage model is created and progressively replaced by bone tissue.

Intramembranous Ossification

The process of bone development where mesoderm (embryonic connective tissue) directly forms bone, producing roofing bones of the skull and clavicles.

Fontanels

Soft unossified membrane spaces (soft spots) in an infant's skull formed during intramembranous ossification.