The forehead of the [affected] side is without motion, the eyelids remain open, the nostril has no motion in breathing, and the mouth is drawn to the opposite side. In this man the sensibility is perfect. - (Charles Bell, 1829).
The facial nerve as the name indicates supplies most of the face. The nerve is responsible for the expressions of the face like - smiling and frowning. It also supplies the muscles that are used to close the eyelids. This seventh cranial nerve is also responsible for taking the taste sensations from the front of the tongue to the brain.
The nerve enters the face in front of the ear and if you place your index finger right in front of the ear, you will be able to feel the pulsations where the nerve enters the face.
The nerve has a very complex course from the brain and as it passes through the skull bone at its base where it is closely related to the ear. It passes through a bony canal before it emerges to supply the facial muscles.
It is felt that the complex course of the nerve is the main reason for it to be prone to injury or any viral infection that results in its swelling and compression of the nerve in the bony canal. As the infection and swelling resolve the palsy disappears.