Intercostal space

The intercostal space is the space between two ribs (Lat. costa). Since there are 12 ribs on each side, there are 11 intercostal spaces.

Importance of intercostal space
Because the chest is protected by the rib cage, the intercostal spaces are important access points in medicine, for example:
 * access for surgical procedures, e.g. resection of (part of) the lung (pneumonectomy), or insertion of a chest tube, performance of pericardiocentesis
 * penetrating trauma of the thorax
 * for percussion and auscultation of underlying structures, e.g. sites for heart auscultation, percussion in Traube's space, etc.

Structures in intercostal space

 * several kinds of intercostal muscle
 * intercostal arteries and associated veins
 * lymphatics
 * nerves

Order of components
Comprehensive insight in the anatomy of the intercostal spaces is mandatory for everyone who practices medicine. One particular concept is that the neurovascular bundle has a strict order: V-A-N, or vein-artery-nerve, from top to bottom (as illustrated). This neurovascular bundle runs high in the intercostal space: therefore, the intercostal space should be penetrated as low as possible by invasive procedures.

In reference to the muscles of the thoracic wall, the intercostal nerves and vessels run just behind the internal intercostal muscles: therefore, they are generally covered on the inside by the parietal pleura, except when they are covered by the innermost intercostal muscles, subcostal muscles or the transversus thoracis muscle.