True about left phrenic nerve
The phrenic nerves contain motor, sensory, and sympathetic nerve fibers. The phrenic nerve originates mainly from the 4th cervical nerve, but also receives contributions from the 5th and 3rd cervical nerves Both phrenic nerves run from C3, C4, and C5 along the anterior scalene muscle deep to the carotid sheath. The accessory phrenic nerve is a branch of the nerve to the subclavius Ref: BD Chaurasia; 7th edition
Lies anterior to anterior scalenous muscle
Posterior to brachial plexus
Posterior to subclan aery
Posterior to hilum left lung
Thorax