Ch 7 Skeletal System

System Objectives

  • Main Functions of Skeletal System

    • Support: Provides structure and shape to the body.

    • Protection: Shields vital organs, e.g., cranium protects the brain.

    • Movement: Muscles attach to bones for leverage and motion.

    • Mineral Storage: Stores minerals like calcium and phosphorus.

    • Blood Cell Formation: Hematopoiesis occurs in the red marrow.

Types of Joint Movement

  • Flexion: Decreasing the angle between bones.

  • Extension: Increasing the angle between bones.

  • Abduction: Moving a limb away from the midline.

  • Adduction: Moving a limb toward the midline.

  • Circumduction: Circular movement of a limb.

  • Rotation: Moving a bone around its axis.

Bone Formation Process

  1. Development: The skeleton starts as cartilage.

  2. Ossification: Cartilage is replaced by mineralized bone over time.

  3. Growth: Bones lengthen and widen through cellular activities of osteoblasts and osteoclasts.

Common Bone and Joint Disorders

  • Osteoarthritis: Degeneration of joint cartilage.

  • Rheumatoid Arthritis: Autoimmune disorder affecting joints.

  • Osteoporosis: Loss of bone density, increasing fracture risk.

  • Osteomyelitis: Bone infection usually caused by bacteria.

Key Terms

  • Abduction: Movement away from the midline.

  • Compact Bone: Dense bone tissue; forms outer layer.

  • Diaphysis: Shaft of a long bone.

  • Osteocytes: Bone cells maintaining bone tissue.

  • Epiphysis: End part of a long bone, contributing to joint structure.

  • Synovial Fluid: Lubricant found in joint cavities.

Skeletal System Structure

  • Axial Skeleton: Includes skull, vertebral column, and rib cage.

  • Appendicular Skeleton: Comprises limbs and girdles (shoulder and pelvic).

Types of Bones

  • Long Bones: Humerus, femur.

  • Short Bones: Carpals, tarsals.

  • Flat Bones: Sternum, skull bones.

  • Irregular Bones: Vertebrae, some facial bones.

Procedure of Bone Healing

  1. Hematoma Formation: Blood clots form at fracture site.

  2. Soft Callus Formation: Cartilage develops to stabilize fracture.

  3. Hard Callus Formation: Bone replaces cartilage.

  4. Remodeling: Compact bone develops and shape is refined via activity of osteoblasts and osteoclasts.

Joints Types and Movements

  • Diarthroses (Freely Movable): Includes ball-and-socket, hinge, pivot joints.

  • Amphiarthroses (Slightly Movable): Like the ribs articulation.

  • Synarthroses (Immovable): Sutures of the skull.

Common Fractures

  • Greenstick: Incomplete fracture common in children.

  • Comminuted: Bone shatters into multiple pieces.

  • Open/Compound: Broken bone penetrates skin.

  • Closed/Simple: No skin penetration.

Age and Its Effects on the Skeletal System

  • Bones lose density and strength with age leading to conditions like osteoporosis.

  • Cartilage loses hydration, causing joint stiffness.

Key Takeaways

  • Knowledge of bone anatomy and functionality is critical for understanding injuries and disorders.

  • Maintaining bone health requires attention to nutrition (calcium, vitamin D) and physical activity.

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