In free functional muscle transplantation, a functioning muscle is removed from another part of the body (e.g. thigh or chest) and transferred into the affected half of the face. The small muscle is connected to a suitable donor nerve and a vascular supply under the cheek skin with the surgical microscope. After healing and activation by the replacement (donor) nerve, the corner of the mouth function can be successfully restored, and improved symmetry of the face can be achieved. The tighter cheek tissues also have a positive effect on the previously often blurred speech and on the difficult food intake of those affected. However, it takes a few months for the missing facial expression to resume due to a newly gained dynamic in the face during which the patient already benefits from an improvement in facial symmetry at rest. The reappearance of a desired age-appropriate nasolabial fold (natural fold between the ala of the nose and the corner of the mouth) often indicates the spontaneous onset of muscle function.