Structure B is the:

Structure B is the:

• A. Zygomatic arch
• B. Foramen magnum
• C. Bony nasal septum (perpendicular plate of ethmoid and vomer)
• D. Body of maxilla (contains the maxillary sinuses)

Answer: (D)

The structure is the body of the maxilla, which is the central upper jaw bone that contains the maxillary sinuses. These air-filled cavities sit inside the body of the maxilla, just beneath the orbit and beside the nasal cavity, making this region the correct match for a structure that houses sinuses. The zygomatic arch is a lateral cheekbone feature, not a sinus cavity. The foramen magnum is a large opening at the skull base, far from the midface. The nasal septum lies within the nasal cavity and is formed by the perpendicular plate of the ethmoid and the vomer, not inside the maxilla. So the best fit for a structure containing the maxillary sinuses is the body of the maxilla.

The structure is the body of the maxilla, which is the central upper jaw bone that contains the maxillary sinuses. These air-filled cavities sit inside the body of the maxilla, just beneath the orbit and beside the nasal cavity, making this region the correct match for a structure that houses sinuses. The zygomatic arch is a lateral cheekbone feature, not a sinus cavity. The foramen magnum is a large opening at the skull base, far from the midface. The nasal septum lies within the nasal cavity and is formed by the perpendicular plate of the ethmoid and the vomer, not inside the maxilla. So the best fit for a structure containing the maxillary sinuses is the body of the maxilla.