A 50 year old woman presented with chief complaints of cough with bloody sputum, dyspnoea, chest pain, loss of appetite and unexplained weight loss. Chest X-Ray revealed a mass in the left lung with elevated left dome of the diaphragm. CT-scan revealed a tumor invading the lung surface anterior to the hilum. Which of the following nerves is most likely to be involved by the tumor?

The phrenic nerve is involved by the tumor as it passes anterior to the hilum of the lung. Phrenic nerve provides sole motor supply to the diaphragm. Normally, the diaphragm flattens when it contracts. Involvement of the phrenic nerve causes elevation of the diaphragm causes elevation of the diaphragm, a condition called diaphragmatic palsy. Other options: Vagus nerve passes poosterior to the hilum of the lung. The intercostal nerve lies in the intercostal space and is not related to the hilum of the lungs. The recurrent laryngeal nerve arises from the vagus nerve, before the vagus nerve passes posterior to the hilum of lungs. Ref:Gray&;s Anatomy 41st edition Pgnoo: 973