There are three salivary glands located on the face: the parotid gland (under-ear gland), the submandibular gland (under-jaw gland), and the sublingual gland (under-tongue gland). Salivary gland hypertrophy occurs when these glands enlarge excessively. When salivary glands become enlarged and sag due to hypertrophy, the face may appear larger and wider overall. Causes of salivary gland hypertrophy can include genetic factors, poor dietary habits, tumors, infections, salivary gland diseases, and skin sagging.