Identify the left phrenic nerve [cross-section] and left vagus nerve [cross-section ] as they cross the arch of the aorta.
The left phrenic nerve enters the thorax between the subclavian artery and vein. The phrenic nerve then crosses the aortic arch, runs anterior to the root of the lung along the left side of the pericardial sac, and passes to the diaphragm.The left vagus nerve enters the thorax between the left common carotid artery and the subclavian artery (Figure 21.4). The vagus nerve crosses the aortic arch [cross-section] and gives off the left recurrent laryngeal nerve [cross-section ] which passes beneath the arch and posterior to the
ligamentum arteriosum. The vagus nerve then passes posterior to the root of the left lung.
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