Which bone acts as a separator between the nasal cavity and the cranial cavity?

The ethmoid bone serves as the critical separator between the nasal cavity and the cranial cavity. It is a complex structure located at the roof of the nasal cavity and contributes to both the walls of the nasal cavity and the orbits of the eyes.

The superior part of the ethmoid bone contains the cribriform plate, which has numerous small openings (olfactory foramina) allowing the passage of the olfactory nerves from the nasal cavity to the brain, highlighting its important role in the sense of smell. Furthermore, the vertical component of the ethmoid, known as the perpendicular plate, extends downward to form part of the nasal septum, further delineating the nasal cavity from the cranial cavity.

In contrast, the maxilla, sphenoid, and palatine bones do not have the same structural role as the ethmoid. The maxilla contributes to the upper jaw and supports the teeth, the sphenoid is situated more posteriorly and plays a role in the base of the skull and orbital structures, and the palatine bones comprise the hard palate and contribute to the floor of the nasal cavity but do not separate the nasal cavity from the cranial cavity in the same manner as the ethmoid. Thus, the ethmoid bone is uniquely