Osteoblasts build bone matrix. Osteoclasts resorb bone. Osteocytes are mature bone cells that help maintain matrix and sense mechanical environment. Remodeling continually balances formation and resorption.
Compact bone forms dense cortical tissue and is organized into osteons in many regions. Spongy/cancellous bone contains trabeculae and is prominent inside many bones. Bone marrow occupies internal spaces; red marrow is involved in blood-cell production.
Diaphysis: shaft. Epiphyses: ends. Metaphysis: transition region associated with growth plate in developing bone. Periosteum: vascular/innervated outer covering except at articular surfaces. Endosteum: lines internal bone surfaces. Articular cartilage: hyaline cartilage covering joint surfaces.
Intramembranous ossification forms bone directly within connective tissue membranes and contributes especially to flat bones of skull and parts of clavicle. Endochondral ossification replaces a cartilage model and forms most bones. Length growth occurs at epiphyseal plates until closure.
Fracture healing broadly progresses through hematoma/inflammatory response, soft callus, hard/bony callus and remodeling. Healing varies with blood supply, stability, health and injury severity. Massage does not accelerate an unstable acute fracture by working directly on it.
Axial: skull, vertebral column and thoracic cage. Appendicular: pectoral girdles/upper limbs and pelvic girdle/lower limbs.
Support · protection · leverage for movement · mineral storage, especially calcium/phosphate · blood-cell formation in red marrow · fat storage in yellow marrow.
Process = projection; foramen = opening; fossa = depression; condyle = rounded articular prominence; tubercle/tuberosity = projections of differing size; crest = ridge; epicondyle = projection near condyle; trochanter = large femoral projection.