The position of the thoracostomy tube is usually between the anterior axillary and midaxillary anatomical lines from anterior to posterior and in either the fourth or fifth intercostal space. The position of the ribs in this region should be clearly marked. Anesthetic should be applied to the superior border of the rib and the inferior aspect of the intercostal space, including one rib and space above and one rib and space below. The neurovascular bundle runs in the neurovascular plane, which lies in the superior aspect of the intercostal space (just below the rib); hence, the reason for positioning the tube on the superior border of a rib (i.e., at the lowest position in the intercostal space).