There is a meatus inside the mouth under normal circumstances may be parotid duct papillae or sublingual caruncle, disease conditions may be caused by mucous cysts, papillomas, etc., as follows. 1. Normal condition: (1) Parotid duct papilla: the opening of the parotid duct is usually located at the buccal mucosa opposite to the buccal surface of the crown of the maxillary second molar, and the mucosa at the opening is slightly elevated, which is called the parotid duct papilla. (2) Sublingual caruncle: a protrusion on the mucous membrane of the floor of the mouth on each side of the tongue tie, which is the opening of the submandibular gland duct and the sublingual gland duct. 2. Disease conditions: (1) Mucous cysts: often arising from injuries to the submucosal glands, the cysts are located in the submucosa and appear as translucent, light blue vesicles. (2) papilloma: a group of local epithelial exophytic and polypoid hyperplasia formed by cauliflower-like or wart-like swelling. There may be other reasons why there is a meatball inside the mouth, it is recommended to go to the hospital in time to clarify the cause of the disease for targeted treatment.