Nerve
Phrenic nerve
Motor nerve of the diaphragm
High-yield
C3, C4, C5 keep the diaphragm alive. Also carries sensation from the central diaphragm, mediastinal pleura, and pericardium.
Overview
The sole motor nerve to the diaphragm, arising in the neck and descending through the thorax on the pericardium.
Reference facts
- Roots
C3, C4, C5 (cervical plexus)
- Course
Descends on the anterior scalene, enters the thorax, and runs anterior to the lung root on the fibrous pericardium to the diaphragm
- Motor
Diaphragm (sole motor supply)
- Sensory
Central diaphragm, mediastinal pleura, pericardium, and diaphragmatic peritoneum (referred to the shoulder tip)
Clinical correlation
Phrenic nerve injury paralyses a hemidiaphragm; diaphragmatic irritation refers pain to the shoulder (C3–C5 dermatomes).