Final answer:
Hiccups, which are spasms of the diaphragm, can be caused by the initiation of the phrenic nerve in the cervical plexus.
Step-by-step explanation:
The initiation of a major nerve in the cervical plexus can cause hiccups, which are spasms of the diaphragm. The phrenic nerve is a systemic nerve from the cervical plexus that innervates the diaphragm. It is connected to the spinal cord at cervical levels 3 to 5, and its motor fibers are responsible for the contractions of the diaphragm that drive ventilation. Therefore, irritation or injury to the phrenic nerve can result in hiccups.