Anatomy

Thoracic Cage

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Thoracic cage

  • Protects the chest organs (the heart and lungs).

Main Structures:

The sternum (aka, breastbone) lies anteriorly.
12 thoracic vertebrae lie posteriorly.
12 ribs articulate with the thoracic vertebrae.

Sternum

  • Manubrium (superiorly)
  • Body (long and flat, middle portion)
  • Xiphoid process
    • Easily injured during chest compression (for CPR).
  • Sternal angle
    • Where manubrium and body meet
    • Easily palpated to find rib 2
  • Sternal indentations:
    • Jugular notch (aka, suprasternal notch) is on the superior border of the manubrium.
    • Clavicular notches are to the sides of the jugular notch; these are where the clavicles (aka, collarbones), articulate with the sternum.
    • Costal notches articulate with the costal cartilages of the ribs (“costal” refers to the ribs).

Rib Types

  • True ribs
    • Ribs 1-7; articulate with the sternum directly via their costal cartilages.
  • False ribs
    • Ribs 8-12; do not articulate directly with the sternum.
    • Ribs 11 and 12 are “floating ribs,” do not articulate at all with the sternum.

Rib Features

  • Head
    • Articulates with the vertebral body; typically comprises two articular surfaces separated by a bony crest.
  • Neck
    • Extends from the head, and terminates at the tubercle.
  • Tubercle
    • Comprises an articular facet, which is where the rib articulates with the transverse process of the vertebra.
  • Shaft
    • Longest portion of the rib, extends from tubercle to rib end.
  • Angle
    • Bend in rib, just lateral to tubercle.

Rib/vertebra articulation

  • Head and tubercle of rib articulate with body and thoracic process of vertebrae.

Intercostal spaces

  • The spaces between the ribs
  • House muscles and neurovascular structures.
    • Intercostal neurovascular bundle, especially the intercostal artery, must be avoided during insertion of a chest tube.

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