The sternocleidomastiod slip and mobilized platysma are brought together
over the defect both for cosmetic reasons and to provide a barrier that
prevents parasympathetic fibers, which normally stimulate parotid
secretion (ultimately via the auriculotemporal nerve), from regenerating
toward and anomalously innervating sweat glands in the overlying facial
skin, causing gustatory sweating (Frey's syndrome). This phenomenon is
seen up to 50% of the time after parotidectomy.