The Brain Stem
The brain stem is connected to the spinal cord and from there to the whole of the central nervous system in the rest of the body. The brain stem controls movements of the throat, so damage to this area may result in impairments in speech and swallowing.
The brain stem also controls consciousness, alertness and functions that are not under conscious control, such as breathing, body temperature, heart rate and blood pressure.
It is therefore an extremely critical area in terms of damage to the brain stem interrupting normal nerve fibres.