Final answer:
The frontal, maxillary, sphenoidal, and ethmoidal cavities form the paranasal sinuses, which are air-filled spaces within specific bones adjacent to the nasal cavity.
Step-by-step explanation:
The frontal, maxillary, sphenoidal, and ethmoidal cavities make up the paranasal sinuses. These are hollow, air-filled spaces located within specific bones of the skull. The frontal sinus is the most anterior and is found above the eyebrows in the frontal bone.
The maxillary sinuses are the largest and are located in the maxillary bones just below the orbits. The sphenoid sinus is positioned posteriorly within the body of the sphenoid bone, just anterior and inferior to the sella turcica. Lastly, the ethmoid air cells are comprised of multiple small spaces situated within the ethmoid bone, between the upper nasal cavity and the medial wall of the orbits.The frontal, maxillary, sphenoidal, and ethmoidal cavities form the paranasal sinuses, which are air-filled spaces within specific bones adjacent to the nasal cavity.