What is the main purpose of brainstem?

Brain stem: The brainstem acts as a connection center or "relay station" between the cerebral cortex and cerebellum, and carries motor signals from the brain to the rest of the body through the spinal cord. The spinal cord and peripheral nervous system. Responsible for the following key functions:

Breathing: Contains essential centers that help to automatically balance respiration, including inspiration and expiration cycles during respiration.

Heart functions: Regulates unconscious actions that influence how heartbeats, including heart rate and blood pressure, work together when necessary.