Phrenic nerves

  • Motor to the diaphragm

  • Contain sensory fibres from its more central part and from the related pleura and peritoneum

    Thoracic course

    Enters the thorax by passing behind the subclavian vein

Course and Relations

Right phrenic nerve
Left phrenic
  • Inclines medially and crosses anterior to the right internal thoracic artery

  • Descends on the lateral side of the right brachiocephalic vein and superior vena cava

  • Then between the pleura and pericardium
    Infront of the root of the lung
  • Pierces the diaphragm to supply it on its deep surface
  • Inclines medially and crosses the left internal thoracic artery

  • Comes to lie anterior to the left subclavian artery

  • Under the cover of the origin of the left brachiocephalic vein

  • Crosses the left vagus just above the aortic arch

  • Crosses the arch infront of the vagus

  • Descends infront of the root of the lung, between the pleura and pericardium
  • Pierces the diaphragm to supply it and its covering peritoneum from below.

  • Branches
    Branches to the diaphragm supply it on its abdominal surface
    Sensory branches are given to:
  1. Diaphragm
  2. Pleura
  3. Pericardium
  4. Peritoneal ligaments of the liver
  5. Inferior vena cava
  6. Supra renal glands