Thoracic Cage
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.