The brainstem is part of the brain that connects to the spinal cord. It has three main components: the midbrain, pons, and medulla oblongata.

The brainstem controls functions such as breathing, blood pressure, body temperature, heart rhythms, hunger and thirst, and sleep patterns. It is also the part of the brain that connects the forebrain and the cerebellum with the spinal cord. All the nerve fibers leaving the brain to go to the limbs and trunk of the body pass through here.