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.