QS Study

Typical intercostal space

It is a potential space between two adjacent typical ribs containing intercostal muscles and is traversed by vessels and nerves that are confined to the thoracic wall. Every space consists of intercostal muscles and a neurovascular bundle of the intercostal plane.


3rd to 6th intercostal spaces are typical intercostal spaces. The blood supply and nerve supply of 3rd-6th intercostal spaces are restricted only up to the thorax as a result of which these 3rd-6th spaces are typical intercostal spaces. So, they are 4 in number.


  1. Above: Lower border of the upper rib. A sharp lower margin of the upper ribs and its cartilage
  2. Below: Upper border of the lower rib. A blunt upper margin of the lower ribs and cartilage.
  3. Anteromedially: Lateral border of the sternum. Lateral border of the sternum between costal notches.
  4. Posteromedially: Body of the corresponding vertebra.

Fig: Typical Intercostal Space Boundary


(a) Muscles (from outer to inner):

  1. External intercostal
  2. Internal intercostal &
  3. Intercostalis intimus.

(b) Vessels:

  1. Anterior intercostal vessels – 2 in each space.
  2. Posterior intercostal vessels – 1 in each space.

(c) Nerves: Intercostal nerves (3 rd to 6th) – Corresponding nerve in corresponding space.

An arrangement of vessels and nerves: From above downwards – (VAN)

  1. Intercostal vein. V
  2. Intercostal artery. A
  3. Intercostal nerve. N

They lie in between internal intercostal & intercostalis intimi muscles.