Skeletal System & Basic Cell Biology Vocabulary

A comprehensive set of vocabulary flashcards covering key terms from the skeletal system anatomy, bone physiology, fracture types and healing, joint classifications, and fundamental cell biology concepts.

Axial Skeleton

The division of the skeleton forming the longitudinal axis of the body; includes skull, vertebral column, and bony thorax.

Appendicular Skeleton

The division of the skeleton consisting of the limbs and girdles (pectoral and pelvic) that attach them to the axial skeleton.

Compact Bone

Dense, smooth, homogeneous osseous tissue forming the external layer of bones.

Spongy Bone

Osseous tissue composed of small needle-like pieces with many open spaces; found mainly at the epiphyses.

Long Bone

Bone type longer than wide, with a shaft and two heads; primarily compact bone (e.g., femur, humerus).

Short Bone

Generally cube-shaped bone containing mostly spongy bone (e.g., carpals, tarsals).

Flat Bone

Thin, flattened, usually curved bone with two thin layers of compact bone sandwiching spongy bone (e.g., ribs, skull).

Irregular Bone

Bone with complex shape that does not fit other categories (e.g., vertebrae, hip).

Diaphysis

The shaft of a long bone composed of compact bone.

Epiphysis

The ends of a long bone composed mostly of spongy bone.

Periosteum

Fibrous connective tissue membrane covering the outer surface of the diaphysis.

Sharpey’s Fibers

Collagen fibers that secure the periosteum to the underlying bone.

Medullary Cavity

Central cavity within the diaphysis that contains yellow marrow in adults and red marrow in infants.

Articular Cartilage

Hyaline cartilage covering the epiphyses; reduces friction at joint surfaces.

Bone Markings

Surface features of bones serving as attachment sites or passageways for nerves and vessels; include projections and depressions.

Osteon (Haversian System)

Structural unit of compact bone consisting of concentric lamellae around a central canal.

Central (Haversian) Canal

Channel in the center of an osteon carrying blood vessels and nerves.

Perforating (Volkmann’s) Canal

Canal running perpendicular to osteons that connects blood and nerve supply between osteons and periosteum.

Lacunae

Small cavities in bone matrix housing osteocytes; arranged in concentric rings.

Lamellae

Concentric rings of bone matrix surrounding the central canal; contain lacunae.

Canaliculi

Tiny canals radiating from the central canal to lacunae, forming a transport network for nutrients.

Ossification

Process of bone formation whereby hyaline cartilage is replaced by bone matrix.

Osteoblast

Bone-forming cell responsible for depositing new bone matrix.

Osteocyte

Mature bone cell residing in lacunae that maintains bone tissue.

Osteoclast

Bone-destroying cell that breaks down bone matrix, releasing calcium.

Appositional Growth

Process by which bones increase in diameter via osteoblast activity on outer surface and osteoclast activity internally.

Bone Remodeling

Continuous process of bone resorption and deposition responding to blood calcium levels and mechanical stress.

Closed (Simple) Fracture

Bone break that does not penetrate the skin.

Open (Compound) Fracture

Bone break where the bone end penetrates the skin.

Comminuted Fracture

Fracture in which the bone breaks into many fragments; common in the elderly.

Compression Fracture

Bone is crushed; typical of porous, osteoporotic bones.

Depressed Fracture

Broken bone portion is pressed inward; common in skull fractures.

Impacted Fracture

Broken bone ends are driven into each other; often occurs during falls.

Spiral Fracture

Ragged break caused by excessive twisting forces; common sports injury.

Greenstick Fracture

Incomplete break where bone bends; common in children.

Gustilo Type I Fracture

Open fracture with a clean wound <1 cm, little soft-tissue damage, and no comminution.

Gustilo Type II Fracture

Open fracture with wound >1 cm, moderate soft-tissue damage, and minimal crushing; no comminution.

Gustilo Type III Fracture

Severely contaminated open fracture with extensive soft-tissue injury; subtypes IIIA (adequate coverage), IIIB (periosteal stripping), IIIC (associated arterial injury).

Hematoma

Blood-filled swelling that forms immediately after a bone fracture.

Fibrocartilage Callus

Temporary splint of collagen fibers and cartilage that bridges bone fracture during healing.

Bony Callus

Hard, bone-based bridge replacing the fibrocartilage callus during fracture repair.

Axial Skeleton

Skeleton section consisting of the skull, vertebral column, and bony thorax.

Cranium

Portion of skull composed of eight flat bones encasing the brain.

Parietal Bone

Paired cranial bone forming most of the superior and lateral skull walls.

Sphenoid Bone

Butterfly-shaped cranial bone forming part of the cranial floor.

Vertebrae

Individual bones of the spinal column separated by intervertebral discs.

Pectoral Girdle

Clavicle and scapula set attaching upper limbs to the axial skeleton.

Pelvic Girdle

Hip bones (ilium, ischium, pubis) supporting lower limbs and protecting pelvic organs.

Synarthrosis

Functionally immovable joint (e.g., skull sutures).

Amphiarthrosis

Slightly movable joint (e.g., intervertebral discs).

Diarthrosis

Freely movable joint; also called a synovial joint.

Cell Theory

Biological principle stating that all organisms are made of cells, the cell is the basic unit of life, and all cells arise from existing cells.

Cell Metabolism

Collective chemical reactions occurring within a cell that provide energy and synthesize molecules.

Energy Utilization (in Cells)

Use of metabolic energy for activities such as molecule synthesis, muscle contraction, and heat production.

Molecular Synthesis (in Cells)

Cellular production of proteins, nucleic acids, lipids, and other molecules determining cell structure and function.