During a radical neck dissection, the surgeon must preserve the cervical rootlets contributing to the phrenic nerve to avoid hemidiaphragm paralysis. The phrenic nerve arises predominantly from which cervical root?

• A C3 root
• B C5 root
• C C2 and C3 roots equally
• D C4 root ✓

Explanation

The phrenic nerve arises predominantly from the C4 cervical root, with contributions from C3 and C5. It passes over the anterior surface of scalenus anterior muscle, descending into the thorax. During neck dissections, the phrenic nerve must be identified and preserved on scalenus anterior. Inadvertent section results in ipsilateral diaphragmatic paralysis, which is particularly problematic in patients with compromised respiratory function. 'C3, 4, 5 keep the diaphragm alive' is the classic mnemonic.

Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.