Answer:
Because the brainstem regulates autonomic functions through cranial nerves arising from it.
Explanation:
The brainstem is the posterior part of the brain that is continuous with the spinal cord. The brainstem has three parts which includes; midbrain, pons and medulla oblongata.
The midbrain play major part in wakefulness and regulation of homeostasis. It is associated with vision, hearing, motor control, sleep and wake cycles, alertness, and temperature regulation.
The pons is situated between the medulla oblongata and the midbrain. It transmit signal information via nerves to the cerebrum through the medulla and to the cerebellum. It also sends sensory signals to the thalamus via sensory nerves. The pons performs both motor and sensory functions. Sensory functions like hearing, equilibrium, taste, and facial sensations such as touch and pain. Motor roles like eye movement, facial expressions, chewing, swallowing, urination, and the secretion of saliva and tears.
The medulla oblongata controls autonomic functions and connects the spinal cord to higher levels of the brain. It also regulate several basic functions of the autonomic nervous system like breathing, heart and blood vessels, digestion, vomiting, coughing, sneezing, and swallowing.
Individuals that suffers Injury to the brainstem, particularly to the medulla oblongata, will have difficulty with these autonomic functions.
