An assessment of the distance between the phrenic nerve and major intrathoracic structures

The phrenic nerves are the only motor innervation of the diaphragm; they also provide major sensory innervation to the central tendon of the diaphragm, mediastinal pleura, pericardium and some viscera of the upper abdomen. This pair of nerves descend through the thorax in close proximity to major structures such as the heart, pericardium, esophagus, vena cava, and aorta. Embryologically, phrenic axon projection is closely related to diaphragm primordium migration within the developing thorax; thus, adult variation may indicate unique diaphragmatic/thoracic development (1,2). Insight into variations in phrenic nerve position will provide physicians with essential anatomical information to reduce iatrogenic phrenic nerve injury during procedures that require intrathoracic intervention