Skeletal System Overview

Skeletal System

• Contains 206 separate bones
• Includes bones, cartilages, joints, ligaments, and connective tissues
• Has 5 primary functions:
  • Support: Provides structural support for the entire body
  • Storage: Stores calcium, phosphate, and energy reserves (lipids)
  • Blood cell production: Red blood cells, white blood cells, and other blood elements are produced in bone marrow
  • Protection: Soft tissues and organs are often surrounded by skeletal elements
  • Leverage: Bones act as levers, providing a rigid structure for muscles to act upon.

Bone Structure

• Supporting connective tissue containing specialized cells and matrix
• Four general shapes:
  • Long (femur)
  • Short (ankle, carpal)
  • Flat (frontal cranium, sternum)
  • Irregular (vertebra)
  • Sesamoid (patella)
• Two types of bone structure:
  • Compact bone: Solid
  • Spongy bone: Network of bone rods separated by space
  • Bone marrow: Also known as myeloid tissue

Bone Cells

• Osteocytes
• Osteoclasts
• Osteoblasts

Bone Growth and Maintenance

• Requires calcium and phosphate salts for normal growth and maintenance
• Vitamins D3, A, and C are important for bone formation
• Hormones (growth hormone, thyroid hormone, sex hormones, calcitonin, parathyroid hormone) are involved

Bone Injury and Repair

• Fractures occur when subjected to extreme loads
• Repair occurs in 4 stages:
  • Formation of fracture hematoma
  • Formation of internal and external callus
  • Osteoblasts replace central cartilage with spongy bone
  • Remodeling of spongy bone at the fracture site

Skeletal Divisions

• Axial division:
  • Forms the central axis of the body, containing 80 bones:
    • Skull (22 bones) and associated bones.
    • Thoracic cage (24 ribs and sternum)
    • Vertebral column (26 bones)
• Appendicular division:
  • Includes bones of limbs and pectoral & pelvic girdles that attach limbs to the trunk.

Skull

• Composed of 22 bones (8 cranial, 14 facial)
  • Cranium bones (8): frontal, parietal, temporal, occipital, sphenoid, ethmoid
  • Facial bones (14): Form the face.
• Connected by immovable sutures

Test your knowledge of the skeletal system, including the structure and functions of bones in the human body. This quiz covers the types of bones, their shapes, and the vital roles they play in support, protection, and blood cell production.