The submandibular glands are a pair of salivary glands that are located in the bottom of the mouth, on each side of the lower jaw. The main function of the submandibular glands is to control the saliva released into the area of the mouth that is located just under the tongue.They produce saliva and amylase.Both help begin the process of digestion.he main function of the submandibular glands is to control the saliva released into the area of the mouth that is located just under the tongue.