Salivary glands have a rather complex structure. There are paired parotid, sublingual, submandibular, as well as those glands, which are called small, and they are located directly in the oral mucosa. The glands produce a secret that is vital for the formation of saliva. Saliva, in turn, is necessary for the formation of food lump, digestion and other processes. That is why any dysfunction of the salivary glands leads to serious consequences.