Paranasal/Facial Sinuses

The paranasal sinuses—frontal, maxillary, ethmoid, and sphenoid—are air-filled cavities within the facial bones that communicate with the nasal cavity via small ostia. Their anatomical relationships to the eyes, ears, and mouth are clinically significant, especially regarding the spread of infection, surgical approaches, and symptomatology.

Connections to the Eyes:

• The ethmoid and maxillary sinuses are directly adjacent to the orbits. The thin lamina papyracea separates the ethmoid sinuses from the medial orbital wall, while the roof of the maxillary sinus forms the orbital floor.
• The sphenoid sinus lies just inferior and medial to the optic nerve and the orbital apex.
• Infections or tumors in these sinuses can erode bone or spread via venous channels, leading to orbital cellulitis, abscess, or even optic neuritis.

Connections to the Ear:

• The sinuses do not directly connect to the middle ear, but the nasopharynx serves as a common pathway. The Eustachian tube opens into the nasopharynx, which is contiguous with the posterior nasal cavity.
• Inflammation or infection in the nasal cavity or sinuses can lead to Eustachian tube dysfunction, predisposing to otitis media, especially in children.

Connections to the Mouth:

• The floor of the maxillary sinus is closely related to the roots of the upper molar and premolar teeth. Dental infections can extend into the maxillary sinus (odontogenic sinusitis), and sinus infections can sometimes present with referred dental pain.
• The nasal cavity communicates with the oral cavity via the nasopharynx posteriorly, but there is no direct connection between the paranasal sinuses and the oral cavity under normal circumstances.
• Surgical or pathological processes (e.g., oroantral fistula) can create abnormal communications between the maxillary sinus and the oral cavity.