Which of the following statements is not correct?

The oral cavity leads into a short pharynx which serves as a common passage for food and air.

The muscularis externa of the stomach has longitudinal, circular and oblique muscle layers.

The tongue is a freely movable muscular organ attached to the floor of the oral cavity by the frenulum.

The upper surface of the tongue has small projections called papillae, all of which bear taste buds.