Final answer:
The irregular ridges or folds on the anterior portion of the hard palate are known as rugae.
Step-by-step explanation:
The irregular ridges or folds located on the anterior portion of the hard palate just behind the maxillary incisors are known as rugae of the hard palate. The hard palate forms the roof of the mouth and the floor of the nasal cavity and is a bony structure formed by the palatine process of the maxillary bones and the horizontal plate of the palatine bones. The mucous membrane that covers this area can form these ridges or folds which can vary in prominence among individuals and serve several purposes, including the allowance for expansion of the palate when swallowing.