The horizontal plate of the palatine bone is the rectangular plate of bone that projects medially from the angle formed with the perpendicular plate. Its serrated medial border joins its bilateral partner to form the posterior third of the hard palate. The serrated anterior border of the plate articulates with the posterior border of the maxilla. The posterior border of the bone forms a free edge that provides attachment for the tensor veli palatini and uvularis muscles. Laterally it unites with the perpendicular plate. The superior surface of the plate forms the posterior floor of the nasal cavity. The inferior surface of the plate is rough and provides attachment to the oral mucosa of the hard palate.

Horizon is a Greek word that means a limiting circle or the circle where the earth and sky meet. It denotes structures in the plane where the earth and sky meet. Plate comes from the Greek platus meaning flat or broad. Its Latin equivalent is lamina.

Lamina horizontalis ossis palatini