Anatomy & Physiology – Skeletal System

44 vocabulary flashcards covering skeletal system functions, cells, structures, bone types, growth mechanisms, remodeling, fracture repair, and regional anatomy.

Support

Primary bone function that provides the rigid framework for the body and anchors soft tissues.

Protection

Bone function in which structures like the cranium and rib cage shield vital organs from injury.

Movement

Bone function whereby skeletal muscles pull on bones acting as levers to create body motion.

Mineral storage

Role of bone in reserving calcium, phosphate, and other minerals for release into the bloodstream when needed.

Hematopoiesis

Blood-cell formation that occurs in red bone marrow.

Osteoblast

Bone-building cell that secretes osteoid and initiates mineralization.

Osteoclast

Large, multinucleate cell that breaks down bone matrix for resorption.

Osteocyte

Mature bone cell housed in lacunae that maintains daily bone metabolism.

Osteogenic cell

Mitotically active stem cell that differentiates into an osteoblast.

Red bone marrow

Marrow type that carries out hematopoiesis by producing blood cells.

Yellow bone marrow

Marrow rich in adipose tissue serving as an energy (fat) store.

Osteoid

Organic portion of bone matrix consisting mainly of collagen fibers and ground substance.

Mineral salts (calcium phosphate)

Inorganic part of bone that hardens osteoid, forming hydroxyapatite crystals.

Spongy bone

Lightweight bone with trabeculae; houses red marrow.

Trabeculae

Lattice-like bars of bone inside spongy bone that align along lines of stress.

Compact bone

Dense outer bone layer composed of orderly osteons.

Osteon

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

Lamellae

Rings of calcified matrix within an osteon.

Central canal

Canal running through an osteon that contains blood vessels and nerves.

Short bones

Cube-shaped bones such as carpals and tarsals that provide stability with limited motion.

Diaphysis

Shaft of a long bone containing the medullary cavity.

Epiphysis

Expanded end of a long bone that articulates with adjacent bones.

Endosteum

Thin vascular membrane lining the medullary cavity and trabeculae surfaces.

Periosteum

Double-layered connective tissue covering the outer surface of bones except at joints.

Longitudinal growth

Increase in a bone’s length via cartilage expansion at the epiphyseal plate.

Epiphyseal plate

Hyaline cartilage growth plate responsible for lengthwise bone growth in children.

Epiphyseal line

Remnant of the epiphyseal plate seen in adult bones after growth stops.

Intramembranous ossification

Bone formation process in which flat bones (e.g., skull, clavicle) develop from fibrous membranes.

Endochondral ossification

Bone formation process in which most bones replace a hyaline cartilage model.

Bone remodeling

Continuous bone resorption and deposition regulated by mechanical stress, hormones, diet, and vitamins.

Calcium homeostasis

Physiologic balance whereby bone releases calcium when blood levels drop and stores it when levels are high.

Hematoma (fracture repair)

First stage of bone healing marked by a blood clot at the fracture site.

Callus (fracture repair)

Fibrocartilaginous tissue bridging a fracture during the second stage of healing.

Axial skeleton

Central skeleton comprising skull, vertebral column, and rib cage.

Appendicular skeleton

Bones of the limbs and the pectoral and pelvic girdles.

Female pelvis

Pelvis that is wider, shallower, and has a pubic arch greater than 90°.

Cervical vertebrae

First seven vertebrae characterized by transverse foramina.

Thoracic vertebrae

Twelve vertebrae that each articulate with a pair of ribs.

Lumbar vertebrae

Lower five vertebrae distinguished by the largest bodies to support weight.

Floating ribs

Ribs 11 and 12 that do not attach anteriorly to the sternum.

Fontanelles

Soft membranous gaps in a newborn’s skull that later ossify.

Humerus

Long bone of the upper arm forming part of the elbow joint with the ulna and radius.

Tibia

Medial, weight-bearing bone of the lower leg.

Fibula

Slender lateral bone of the lower leg that bears the lateral malleolus.