Have you ever tried to drink something after a visit to the dentist? One side of my mouth had feeling but the other side didn’t. The side of my mouth not affected by the numbing medication used by my dentist responded as normal. I held the coffee cup to my mouth and took a sip. OPPS! Coffee went into my mouth and dribbled out one side. This condition was temporary, but it gave me more empathy for people experiencing facial paralysis due to maladies resulting in damage to nerves controlling facial nerves.
Nerves
Nerves send electrical coded messages to the brain where it is decoded. This transfer of electrical signals might be compared sending and receiving messages via the telegraph system. 
Morse Code is a combination of dots and dashes that represent letters of the alphabet, but the code is of no value unless it is received by someone who can decode it. Like tapping a telegraph key send out a series of electrical impulses. In like manner, tapping or touching the coffee cup to my mouth sent out electrical impulses from the nerves in my lips. The problem was that the nerves on one side of my mouth were not able to send messages due to being deadened by medication.
The purpose of the medication was to shut down the nerves, thus making them unable to send out pain or any other sensory messages. Trying to drink coffee resulted in half of my mouth responding while the other half was lifeless and allowed the liquid dribble down one side of my face
More Information About Nerves on This Website
Anatomy and Physiology Glossary
Nervous and Endocrine System Glossary
You can find more information about nerves and other parts of the human body in this book, “The Human Body for Every Kid”
