Intercostal spaces and neurovascular bundle

• Intercostal space: space between two adjacent ribs and their costal cartilages; 11 intercostal spaces on each side.
• 3rd to 6th spaces are typical, as their nerve and vessel supply stays confined to the thorax.

Contents of a Typical Intercostal Space

• Each typical space contains:
  • Three intercostal muscles: external, internal, innermost (intercostalis intimus)
  • Intercostal nerve, intercostal artery, intercostal vein
  • Intercostal lymph vessels and nodes
• All three intercostal muscles support the ribs against separation; nerve supply of all three is by intercostal nerves.
• Inspiration: external intercostal acts. Expiration: internal and innermost intercostal act.
• Strictly, the innermost intercostal (intercostalis intimi) is not truly within the intercostal space, as it lies deep to the ribs.

Neurovascular Bundle: Plane and Order