This position is determined by palpating the sternal angle, which is the point of articulation of rib II. Counting inferiorly will determine the rib number and simple observation will determine the positions of the anterior axillary and midaxillary lines. Insertion of any tube or needle below the fifth interspace runs an appreciable risk of crossing the pleural recesses and placing the needle or the drain into either the liver or the spleen, depending upon which side the needle is inserted.