Lecture on the Axial Skeleton

Introduction to Axial Skeleton

• Components: Axial skeleton includes the spine, rib cage, and skull. Focus in this lecture on the spine, rib cage, and sternum.

The Spine (Vertebral Column)

• Sections: Cervical, Thoracic, Lumbar, Sacrum, Coccyx.

Cervical Spine

• Vertebrae: 7 vertebrae (C1 - C7).
• Abbreviation: C/S.
• Special Vertebrae:
  • C1 (Atlas): No body or spinous process.
  • C2 (Axis): Notable for the Dens (Odontoid process).

Thoracic Spine

• Vertebrae: 12 vertebrae (T1 - T12).
• Abbreviation: T/S.
• Connection: Each vertebra connects to ribs.

Lumbar Spine

• Vertebrae: 5 vertebrae (L1 - L5).
• Abbreviation: L/S.
• Characteristics: Larger bodies to support more weight.

Sacrum

• Characteristics: 5 fused vertebrae.
• Function: Connects the spine to the pelvis.

Coccyx

• Characteristics: 3 to 5 fused vertebrae.
• Known as: Tailbone.

Mnemonic for Vertebrae Count

• Trick: Breakfast, lunch, dinner (7, 12, 5).

Spinal Cord

• Function: Protected by the spine.
• Ends at: Approximately L1 or L2.

Medical Relevance

• Lumbar Puncture: Performed at L4 to avoid spinal cord.

Naming Conventions

• Example: C4, T4, S3 (denotes position in spine).

Vertebrae Anatomy

• Views: Superior and Lateral.
• Components:
  • Body: Main weight-bearing part.
  • Spinous Process: Posterior projection.
  • Transverse Process: Lateral projections.
  • Articular Facets: Joint-forming parts.
  • Costal Facets: Present in thoracic vertebrae only.
  • Transverse Foramen: Present in cervical vertebrae only.
  • Lamina: Connects transverse and spinous processes.

Rib Cage, Sternum, and Thoracic Cage

• Components: 12 pairs of ribs, thoracic spine, sternum.

Sternum

• Parts:
  • Manubrium: Upper part.
  • Body: Main portion.
  • Xiphoid Process: Smallest, inferior part.

Ribs

• Types:
  • True Ribs: 1 through 7, attach directly to sternum.
  • False Ribs: 8 through 10, attach to costal cartilage above.
  • Floating Ribs: 11 and 12, do not attach to sternum.

Rib Anatomy

• Costal Groove: Houses intercostal nerve, artery, and vein.

Conclusion

• Review: Axial skeleton consists of key supportive and protective structures including the spine, sternum, and ribs.