Which anatomical landmark marks the boundary between the primary and the secondary palate?

Correct answer: D. The incisive foramen

• A. The midpalatal suture is the SAGITTAL midline union between the two lateral palatine processes that together form the secondary palate. It runs front to back within the secondary palate; it does not divide primary from secondary.
• B. The greater palatine foramen transmits the greater palatine neurovascular bundle near the third molar region.
• C. The posterior nasal spine is the posterior extremity of the hard palate, not the primary/secondary junction.
• D. Correct. The INCISIVE FORAMEN is the landmark. Anterior to it lies the PRIMARY palate (the premaxilla, carrying the four incisors, derived from the medial nasal processes). Posterior to it lies the SECONDARY palate (from the lateral palatine shelves of the maxillary processes). The junction is TRANSVERSE/diagonal, running from the incisive foramen laterally toward the canine region — which is why a cleft of the primary palate involves the lip and alveolus, while a cleft of the secondary palate involves the hard and soft palate.