You're probably thinking to yourself, "We're talking about the brain, not the bloody spine, this guy's bonkers". But dig this.
The spine, if you haven't noticed already, is realllllllyyyyyy important. It runs through the entirety of your back, is in charge of reflexes and relaying information to the brain, heck, it allows you to walk for goodness sake.
It's half ya damn nervous system.
The top of the spine, which is also the part that connects to the brain (brainstem), is the MEDULLA OBLANGATA. The medulla oblangata (or medulla for short) is one of the most important parts of the body as a whole, for it controls heartbeat and breathing (which is paramount to survival, just saying). Damage to this part of the brain (I can guarantee you) means almost certain death. It's really just an "on/off" button.
Next comes the pons (Latin for "bridge), serving as a communication center with the Central Nervous System and the rest of the brain.
After the pons comes the RETICULAR FORMATION, responsible for arousal (NOT THAT KIND OF AROUSAL) and alertness in the body.
The THALAMUS, located of the top of the brainstem, is the sensory switchboard for the brain, everything sensory related going through this part but smell.