Submucosa is absent in which part of hard palate?

Submucosa is absent in the medial portion of the hard palate; thus the tissue has a firmer feeling when palpated. This firm feeling is enhanced as a result of the firmness with which the lamina propria is attached to the underlying bone; thus the lamina propria serves as a mucoperiosteum. The landmarks on the hard palate, the palatal rugae and the median palatal raphe, have histological features similar to those of the medial portion of the hard palate.