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).
Frequently asked questions
What are the roots of the phrenic nerve?
The phrenic nerve arises from C3, C4, C5 (cervical plexus).
What muscles does the phrenic nerve supply?
The phrenic nerve supplies the diaphragm (sole motor supply).
What is the sensory distribution of the phrenic nerve?
The phrenic nerve carries sensation from the central diaphragm, mediastinal pleura, pericardium, and diaphragmatic peritoneum (referred to the shoulder tip).
What is the course of the phrenic nerve?
Descends on the anterior scalene, enters the thorax, and runs anterior to the lung root on the fibrous pericardium to the diaphragm.