Skeletal System Notes

Skeletal System

Introduction (November 4, 2020)

  • Happy Wednesday!
  • Two questions were posed:
    1. Identify tissues (A and B - not specified in this excerpt)
    2. Name one way the skin and the skeleton work together to maintain homeostasis.

Introduction to the Skeletal System (BIOL 2401)

Functions of the Skeletal System

  • There are seven important functions of bones:
    • Support
      • For body and soft organs.
    • Protection
      • Protects brain, spinal cord, and vital organs.
    • Movement
      • Levers for muscle action.
    • Mineral and growth factor storage
      • Calcium and phosphorus and growth factors reservoir.

Functions Continued

  • Blood cell formation
    • Hematopoiesis occurs in red marrow cavities of certain bones.
  • Triglyceride (fat) storage
    • Fat, used for an energy source, is stored in bone cavities.
  • Hormone production
    • Osteocalcin secreted by bones helps to regulate insulin secretion, glucose levels, and metabolism.

Classification of Bones

  • 206 named bones in human skeleton.
  • Divided into two groups based on location:
    • Axial skeleton
      • Long axis of body.
      • Skull, vertebral column, rib cage.
    • Appendicular skeleton
      • Bones of upper and lower limbs.
      • Girdles attaching limbs to axial skeleton.

Classifications of Bones

  • Bones are also classified according to one of four shapes:
    • Long bones
      • Longer than they are wide.
      • Limb bones.
    • Short bones
      • Cube-shaped bones (in wrist and ankle).
    • Sesamoid bones
      • Form within tendons (example: patella).
      • Vary in size and number in different individuals.

Classification of Bones (cont.)

  • Flat bones
    • Thin, flat, slightly curved.
    • Sternum, scapulae, ribs, most skull bones.
  • Irregular bones
    • Complicated shapes.
    • Vertebrae and hip bones.
  • Wormian bones or Sutural bones
    • Located between the flat bones of the skull.
    • They vary in size from a grain of sand to a quarter.

Ossa suturalia

  • Sutural Bones

Classification of Bones (Images)

  • (a), (b), (c), (d) - Refer to images for visual classification (not included in text).

Types of Bones

  • Bones can be classified by SHAPE.
  • ANATOMY TYPES OF BONES