The nerve related with diaphragm is phrenic nerve. This is a spinal nerve. The ventral rami of first four pairs of cervical nerves combine to form a cervical plexus on each side. Branches from cervical plexus innervates the regions of head, thorax and neck on the ventral side. Three slender branches one each from the ventral rami of 3rd4th and 5th cervical nerves merge to form the phrenic nerve to innervate the diaphragm.