The Phrenic nerve arises from C3 - C5. It
is formed at the superior lateral portion of the scalenus anterior and courses
to its medial border. It is located in the prevertebral fascia. It is crossed
anteriorly by the suprascapular and transverse cervical arteries. The
right phrenic nerve lies on the lateral aspect of the venous channel of the
right heart. The left
phrenic nerve is crossed by the thoracic duct, which joins the bifurcation of
the left brachiocephalic vein. It is motor to the diaphragm and sensory to the
parietal pleura and the parietal peritoneum covering the diaphragm.
Severance of the phrenic nerve results in paralysis of the corresponding half of the diaphragm.