ABSTRACT
The intercostal muscles are true chest wall muscles and are involved in respiration. It is important to remember that they are made of three components, namely the external intercostal, internal intercostal and innermost intercostal groups. The neurovascular bundle sits between the internal and innermost segments. It is positioned in a groove lying inferiorly in the rib. When marking, tapping or draining chests it is best to avoid the neurovascular bundle by aiming immediately above the rib.
