![The brainstem The brainstem](http://brainstemimaginglab.martinos.org/wp-content/uploads/2018/03/A.SliderImage.jpg)
The brainstem
The brainstem is a stem-like area at the base of the brain. In humans, it is slightly bigger than a thumb. Yet, it contains over 300 subregions (nuclei and sub-nuclei) that regulate several vital functions (sleep and wakefulness, respiration, heartbeat, body and head motion, sensations, pain, emotions).