Smiling and other facial expressions require an intact Facial Nerve on both sides of the face. Sometimes children are born without a facial nerve. More commonly, a child's facial nerve is damaged from an injury or during a surgical procedure such as tumor removal. This results in the inability of the child to show normal facial expression. Facial Re-animation is the term used for microsurgical techniques aimed at repairing the facial nerve and/or transplanting a muscle from the leg to the face.