Question
A 23-year-old man is brought to the emergency department by a coworker for an injury sustained at work. He works in construction and accidentally shot himself in the chest with a nail gun. Physical examination shows a bleeding wound in the left hemithorax at the level of the 4th intercostal space at the midclavicular line. Which of the following structures is most likely injured in this patient?
| A. | Left middle lobe of the lung |
| B. |
Right atrium of the heart |
| C. |
Left atrium of the heart |
| D. |
Left upper lobe of the lung |
Show Answer
|
Correct Answer � D Explanation |
 |
Left middle lobe of the lung
- Unlike the right lung, the left lung has no middle lobe. The left lung has a sub-segment, the lingula of the left lung, which is thought to be a remnant of the middle lobe.
Right atrium of the heart
- While the right atrium of the heart is located between the 3rd and 4th intercostal space, it is mainly located posterior to the sternum. It is not located in the left hemithorax, where this patient’s injury occurred.
Left atrium of the heart
- The left atrium of the heart is located between the 2nd and 3rd intercostal space slightly lateral to the left sternal border, which is superior and medial to the point of injury in this patient.
Left upper lobe of the lung
- The left upper lobe of the lung is anterior to the left lower lobe with boundaries extending from above the first rib to about the 6th intercostal space along the midclavicular line.
- Thus, a penetrating wound in the 4th intercostal space of the anterior left chest will most likely involve the left upper lobe.