Chapter 6: Cartilage and Bone Tissue

Types and Functions of Cartilage

Cartilage is a specialized connective tissue that provides support and flexibility to various parts of the body. It is classified based on structure and function.

• Hyaline cartilage: Most abundant; found in nose, trachea, larynx, and at the ends of long bones. Provides smooth surfaces for joint movement.

• Elastic cartilage: Contains elastic fibers; found in ear and epiglottis. Provides flexibility.

• Fibrocartilage: Contains thick collagen fibers; found in intervertebral discs and pubic symphysis. Provides strong support and resists compression.

Perichondrium: A dense layer of connective tissue that surrounds most cartilage, providing nutrients and support.

Cartilage Growth

• Appositional growth: New cartilage is added to the surface by chondroblasts in the perichondrium.

• Interstitial growth: Chondrocytes within the cartilage divide and secrete new matrix, expanding cartilage from within.

Classification of Bones

Bones are classified by location and shape:

• Axial skeleton: Skull, vertebral column, and thoracic cage.

• Appendicular skeleton: Limbs and girdles.

Bones are also classified by shape:

• Long bones: Longer than wide (e.g., femur, humerus).

• Short bones: Cube-shaped (e.g., carpals, tarsals).

• Flat bones: Thin and broad (e.g., sternum, skull bones).

• Irregular bones: Complex shapes (e.g., vertebrae, hip bones).

Bone Structure

• Diaphysis: Shaft of a long bone.

• Epiphysis: Ends of a long bone.

• Periosteum: Outer fibrous covering of bone.

• Endosteum: Membrane lining the medullary cavity.

• Sharpey's (perforating) fibers: Collagen fibers that anchor periosteum to bone.

Bone Cells and Bone Matrix

• Osteogenic cells: Stem cells that differentiate into osteoblasts.

• Osteoblasts: Bone-forming cells; secrete bone matrix.

• Osteocytes: Mature bone cells; maintain bone matrix.

• Osteoclasts: Bone-resorbing cells; break down bone matrix.

Bone matrix: Composed of organic (collagen fibers) and inorganic (hydroxyapatite crystals) components, providing strength and flexibility.

Bone Remodeling and Growth

• Bone remodeling: Continuous process of bone resorption and formation, involving osteoclasts and osteoblasts.

• Appositional growth: Increase in bone thickness.

• Longitudinal growth: Occurs at the epiphyseal plate (growth plate) through proliferation and ossification of cartilage.

Microscopic structure of compact bone: Organized into osteons (Haversian systems) with central (Haversian) canals, lamellae, lacunae, canaliculi, and perforating (Volkmann's) canals.

Bone Healing and Homeostasis

• Bone fracture healing stages: Hematoma formation, fibrocartilaginous callus formation, bony callus formation, bone remodeling.

• Hormonal control: Parathyroid hormone (PTH) increases blood calcium by stimulating osteoclasts; calcitonin lowers blood calcium by inhibiting osteoclasts.

• Wolff's Law: Bone grows and remodels in response to the forces placed upon it.

Bone Diseases

• Osteoporosis: Decreased bone mass and increased fracture risk.

• Osteomalacia: Softening of bones due to vitamin D deficiency in adults.

• Rickets: Softening of bones in children due to vitamin D deficiency.

• Paget's disease: Disorganized bone remodeling.

Chapter 7: Axial Skeleton and Joints

Axial Skeleton Bones Identification

The axial skeleton includes the skull, vertebral column, and thoracic cage. Key bones and features should be identified for anatomical study.

• Skull: Cranial and facial bones.

• Vertebral column: Cervical, thoracic, lumbar, sacral, and coccygeal vertebrae.

• Thoracic cage: Ribs and sternum.

Sutures and Bone Markings

• Sutures: Immovable joints between skull bones (e.g., coronal, sagittal, squamous, lambdoid).

• Bone markings: Projections, depressions, and openings on bones for attachment and passage of structures.

Vertebral Column

• Types of vertebrae: Cervical (7), thoracic (12), lumbar (5), sacral (5 fused), coccygeal (4 fused).

• Structural and functional differences: Cervical vertebrae have transverse foramina; thoracic have facets for ribs; lumbar are large and robust.

• Male vs. female pelvis: Female pelvis is wider and shallower for childbirth.

• True, false, and floating ribs: True ribs (1-7) attach directly to sternum; false ribs (8-10) attach indirectly; floating ribs (11-12) do not attach to sternum.

Chapter 8: Joints (Articulations)

Classification of Joints

Joints are classified by structure and function:

• Structural classification: Fibrous, cartilaginous, synovial.

• Functional classification: Synarthrosis (immovable), amphiarthrosis (slightly movable), diarthrosis (freely movable).

Synovial Joints

• Components: Synovial cavity, synovial fluid, articular capsule (synovial membrane and fibrous capsule), articular cartilage, reinforcing ligaments.

• Types of synovial joints: Plane, hinge, pivot, condyloid, saddle, ball and socket.

• Functional types: Nonaxial, uniaxial, biaxial, multiaxial.

• Movements: Gliding, angular (flexion, extension, abduction, adduction), rotation, special movements (e.g., pronation, supination).

Knee Joint Structure

• Cruciate ligaments: Stabilize anterior-posterior movement.

• Menisci: Fibrocartilage pads that improve fit and absorb shock.

• Bursa and tendon sheaths: Reduce friction between moving structures.

Joint Stability and Muscle Tone

• Muscle tone: Continuous partial contraction of muscles stabilizes joints.

• Articular surface: Shape and fit of bone ends affect stability.

Joint Diseases

• Bursitis and tendinitis: Inflammation of bursae or tendons, often due to overuse or infection.

• Arthritis: Inflammation of joints. Types include:

  • Osteoarthritis: Degenerative, due to wear and tear.

  • Rheumatoid arthritis: Autoimmune, chronic inflammation.

  • Gouty arthritis: Caused by uric acid crystal accumulation.

Summary Table: Types of Joints

Key Equations

• Wolff's Law (qualitative): Bone adapts to the loads under which it is placed.

• Calcium Homeostasis:

Additional info: Some details, such as the specific number of vertebrae and the distinction between types of arthritis, were expanded for academic completeness.