The phrenic nerve arises from the C3-C5 spinal roots (mainly C4). it descends through the neck and thorax to innervate the ipsilateral hemidiaphragm.
Branches of C3,C4, and C5 → Phrenic Nerve
This nerve controls the activity of the ipsilateral hemidiaphragm.
CAUSE OF INJURY
Compression/irritation of this nerve can be caused by various mechanisms:
- Mass effect due to malignancy
Diaphragmatic irritation can manifest as dyspnea amor hiccups
Shoulder pain: this nerve will refer pain to the shoulder on the affected side. This is because the area innervated by the supraclavicular nerve originates from C3, C4.
Respiratory distress can be a consequence of phrenic nerve palsy. Decreased breath sounds can be present, and an elevated hemidiaphragm can be noticed on a chest X-ray.