The NCD should not be placed medial to which landmark to avoid entering the cardiac box?

• A. Nipples line
• B. Anterior axillary line
• C. Midclavicular line
• D. 2nd intercostal space

Answer: (A)

The concept here is avoiding injury to the heart by staying outside the heart’s protective area, the cardiac box. The heart sits beneath the chest wall and its lateral boundary roughly follows the nipple line. If you place an NCD medial to that line, you risk entering the cardiac box and injuring the heart. That’s why the safe approach is to keep the entry point lateral to the nipple line, typically along a course that stays away from the chest’s midline and toward the anterior axillary line in the lower thorax. The other landmarks are either further lateral or higher up and still avoid the heart, but the key point for this question is that crossing medial to the nipple line brings you into the cardiac box, which you want to avoid.