phrenic nerve (right, anatomy)

Last reviewed 01/2018

The phrenic nerve on both sides originates from the ventral rami of the third to fifth cervical nerves. It passes inferiorly down the neck to the lateral border of scalenus anterior. Then, it passes medially across the border of scalenus anterior parallel to the internal jugular vein which lies inferomedially. At this point it is deep to the prevertebral fascia, the transverse cervical artery and the suprascapular artery.

At the anterior, inferomedial margin of scalenus anterior and hence superficial to the second part of the right subclavian artery, the right phrenic nerve passes medially to cross the pleural cupola deep to the subclavian vein. More medially, it crosses the internal thoracic artery at approximately the level of the first costochondral junction.

Within the thorax the right phrenic nerve is in contact with mediastinal pleura laterally and medially, in succession from superior to inferior, the following venous structures:

• right brachiocephalic vein
• superior vena cava
• pericardium of the right atrium
• inferior vena cava

From the level of the superior vena cava it is joined by the pericardiophrenic artery and both run inferiorly anterior to the lung root.

The right phrenic nerve pierces the diaphragm in its tendinous portion just slightly lateral to the inferior vena caval foramen. It then forms three branches on the inferior surface of the diaphragm: anterior, lateral and posterior. These ramify out in a radial manner from the point of perforation to supply all but the periphery of the muscle.