<prompt> Phrenic nerve isMotor nerve to diaphragmArises chiefly from 3rd cervical nerve, also receives contribution from 4th and 5th cervical nervesThe nerve runs vertically on the anterior surface of scalenus anteriorIt lies anterior to prevertebral fascia  <response>: Phrenic nerve is a mixed nerve, mainly arises from 4th cervical nerve. It lies behind prevertebral fascia and in front of scalenus anterior. 