The mouth is the first station where food gets digested. This digestion takes place due to the secretion of saliva. Saliva also keeps the teeth healthy, the mouth moist and helps you swallow. It is secreted by 3 major pairs of salivary glands, namely the parotid glands, submandibular glands and sublingual glands. The submandibular glands are located a little below the mandible or jaw bone. Its secretions enter the oral cavity through narrow ducts into the floor of the mouth.