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Anatomy & Physiology: Bone and Skeletal System Fundamentals

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Terms in this set (28)

  • Periosteum

    Tough connective-tissue covering on the outside of bone except where articular cartilage covers joints; contains blood vessels, nerves, and bone-forming cells.

  • Endosteum

    Thin membrane lining internal bone surfaces, including the medullary cavity and trabeculae.

  • Haversian system (osteon)

    Cylindrical structural unit of compact bone; concentric rings of bone matrix surround a central canal containing blood vessels and nerves.

  • Osteocyte

    Mature bone cell housed in lacunae that maintains bone tissue.

  • Osteoblast

    Bone-forming cell that secretes bone matrix (osteoid).

  • Osteoclast

    Cell that breaks down or resorbs bone tissue during remodeling.

  • Compact bone

    Dense, strong bone tissue organized into osteons; provides strength and resistance to bending.

  • Spongy bone

    Bone tissue arranged as trabeculae with spaces containing marrow; lighter and aligns with stress.

  • Long bones

    Bones longer than wide with a shaft and two ends; examples include femur and humerus.

  • Intramembranous ossification

    Bone forms directly within connective tissue membrane without a cartilage model; forms flat skull bones and clavicle.

  • Endochondral ossification

    Bone replaces a hyaline cartilage model; forms most bones including long bones.

  • Epiphyseal plate

    Cartilage growth plate in long bones where lengthening occurs; later becomes the epiphyseal line.

  • Functions of the skeletal system

    Support, protection, movement, mineral storage/release, and blood-cell formation (hematopoiesis).

  • Bone remodeling

    Continuous process where osteoclasts resorb bone and osteoblasts deposit new matrix to repair damage and regulate minerals.

  • Parathyroid hormone (PTH)

    Hormone that raises blood calcium by increasing bone resorption, kidney calcium retention, and vitamin D activation.

  • Calcitonin

    Hormone from thyroid C cells that lowers blood calcium by inhibiting osteoclast activity; less dominant than PTH in adults.

  • Axial skeleton

    Central framework including skull, vertebral column, ribs, and sternum; consists of 80 bones.

  • Appendicular skeleton

    Includes upper and lower limbs plus pectoral and pelvic girdles; consists of 126 bones.

  • Vertebral column curves

    Cervical and lumbar curves are convex forward (secondary); thoracic and sacral curves are convex backward (primary).

  • Scoliosis

    Abnormal lateral (side-to-side) curvature of the vertebral column.

  • Pectoral girdle

    Clavicle and scapula; attaches upper limbs, prioritizes mobility, and is relatively light.

  • Pelvic girdle

    Right and left hip bones; attaches lower limbs, transfers body weight, and prioritizes stability and organ protection.

  • Typical female pelvis features

    Wider and shallower with larger pelvic inlet/outlet and wider subpubic angle to accommodate childbirth.

  • Typical male pelvis features

    Narrower and deeper with smaller pelvic inlet/outlet and narrower subpubic angle; generally more robust bone markings.

  • Fracture repair stages

    Hematoma formation, soft callus formation, bony callus formation, and remodeling into lamellar bone.

  • Canaliculi

    Tiny channels connecting lacunae that allow osteocytes to exchange nutrients and wastes.

  • Marrow cavity (medullary cavity)

    Hollow space in the diaphysis of a long bone; contains yellow marrow in adults.

  • Sesamoid bone

    Bone that develops within a tendon to reduce friction or alter tendon pull; the patella is the largest example.