The phrenic nerve is derived from the cervical plexus and receives innervation from the C3, C4, and C5 nerve roots. It is the longest branch of the cervical plexus.

Why does phrenic nerve supply diaphragm?

The C3-C5 spinal nerves in the neck give rise to the phrenic nerve, a mixed motor and sensory nerve.
The diaphragm, the main muscle of respiration, is exclusively controlled by the nerve, making it essential for breathing.

What organ does this nerve supply?.

The jejunum receives both intrinsic and extrinsic nerve supply.
The preganglionic parasympathetic and postganglionic sympathetic branches of the celiac plexus provide the autonomic extrinsic supply.
These neurons go via branches of the major vessels from the mesentery into the jejunum.

What are the 4 types of nerves?

It is conventional, however, to describe nerve types on the basis of their function: motor, sensory, autonomic or cranial.