Nerve
Phrenic nerve
Cervical nerve that drives each half of the diaphragm
High-yield
C3–C5 supply diaphragmatic motor fibers. Phrenic sensory fibers also link irritation near the central diaphragm to possible shoulder-tip pain.
Overview
Each phrenic nerve begins in the neck and reaches its side of the diaphragm after descending through the chest. In the thorax it crosses in front of the lung root and follows the pericardium.
Reference facts
- Root value
- C3–C5 anterior rami, usually with a major C4 contribution
- Course
- Anterior surface of anterior scalene, then anterior to the lung root along the pericardium toward the diaphragm
- Motor
- Motor supply to the diaphragm on the same side
- Sensory
- Central diaphragmatic coverings, mediastinal pleura and fibrous/parietal pericardium
Clinical correlation
A substantial unilateral injury can weaken or paralyze one hemidiaphragm. Shoulder-tip pain can be referred from phrenic sensory territories, but many unrelated conditions also cause shoulder pain.
Frequently asked questions
What are the roots of the phrenic nerve?
The phrenic nerve arises from C3–C5 anterior rami, usually with a major C4 contribution.
What muscles does the phrenic nerve supply?
The phrenic nerve supplies the motor supply to the diaphragm on the same side.
What is the sensory distribution of the phrenic nerve?
The phrenic nerve carries sensation from the central diaphragmatic coverings, mediastinal pleura and fibrous/parietal pericardium.
What is the course of the phrenic nerve?
Anterior surface of anterior scalene, then anterior to the lung root along the pericardium toward the diaphragm.