Bone and Cartilage Anatomy

Hyaline cartilage

Glassy matrix, fine collagen; reduces friction; nose, trachea, ribs, joints.

Fibrocartilage

Thick collagen fibers; resists compression; intervertebral discs, pubic symphysis, menisci.

Elastic cartilage

Elastic fibers + collagen; flexible support; ear and epiglottis.

Chondroblasts

Cartilage‑forming cells that produce matrix.

Chondrocytes

Mature cartilage cells housed in lacunae.

Lacunae

Small spaces that contain chondrocytes or osteocytes.

Extracellular matrix (Cartilage)

Protein fibers + ground substance surrounding cartilage cells.

Perichondrium

Dense connective tissue covering cartilage; contains stem cells.

Cartilage functions

Supports soft tissues, provides smooth surfaces, models bone formation.

Bone functions

Support, protection, movement, mineral/energy storage, blood cell formation.

Long bones

Longer than wide; act as levers; femur, humerus.

Short bones

Cube‑shaped; stability; carpals, tarsals.

Flat bones

Thin, flat; protect organs; skull, sternum.

Irregular bones

Complex shapes; vertebrae, pelvis.

Compact bone

Dense outer bone providing strength.

Spongy bone

Porous bone with trabeculae; houses marrow.

Proximal epiphysis

End of bone closest to body trunk.

Distal epiphysis

End of bone farthest from trunk.

Diaphysis

Shaft of long bone.

Metaphysis

Region between diaphysis and epiphysis.

Epiphyseal line

Remnant of growth plate.

Articular cartilage

Hyaline cartilage covering joint surfaces.

Medullary cavity

Central cavity containing marrow.

Endosteum

Lining of medullary cavity; contains bone cells.

Periosteum

Outer covering of bone; anchors tendons/ligaments.

Perforating fibers

Collagen fibers attaching periosteum to bone.

Nutrient foramen

Opening for blood vessels and nerves.

Yellow bone marrow

Fat storage tissue.

Red bone marrow

Site of blood cell formation.

Osteoprogenitor cells

Stem cells that produce osteoblasts.

Osteoblasts

Bone‑forming cells that secrete matrix.

Osteocytes

Mature bone cells maintaining matrix.

Osteoclasts

Bone‑resorbing cells that break down matrix.

Organic matrix

Collagen + proteins; gives flexibility.

Inorganic matrix

Calcium phosphate crystals; gives hardness.

Osteon

Structural unit of compact bone.

Central canal

Canal for blood vessels and nerves.

Lamellae

Concentric rings of matrix.

Canaliculi

Channels connecting lacunae.

Perforating canal

Connects central canals across osteons.

Trabeculae

Lattice‑like bone structures.

Intramembranous ossification

Bone develops from mesenchyme; forms flat bones and clavicle.

Endochondral ossification

Bone replaces cartilage model; forms most bones.

Interstitial growth

Lengthwise growth at epiphyseal plate.

Appositional growth

Width growth via periosteum.

Fracture repair stages

Hematoma → soft callus → hard callus → remodeling.

Osteomalacia

Soft bones due to vitamin D deficiency; rickets in children.

Osteoporosis

Bone density loss due to aging, hormones, or inactivity.