Sinus Drainage
Frontal Sinus
  • A pair of air filled cavities in the frontal bone,located superolateral to the nasal ridge
  • Connects with the middle nasal meatus via the frontonasal duct, which drains into the semilunar hiatus (a semicircular opening on the lateral aspect of the middle nasal meatus)
Ethmoidal Sinus A collection of air-filled cavities located between the orbits and the nasal cavity.

  • Anterior ethmoidal air cells (the largest of which is the ethmoid bulla); drain into the middle nasal meatus
  • Middle ethmoidal air cells; drain into the middle nasal meatus
  • Posterior ethmoidal cells; drain into the superior nasal meatus

Present at birth
Sphenoid Sinus
  • A pair of air filled cavities in the sphenoid bone and most posterior paranasal sinuses.
  • Drains into the sphenoethmoidal recess in the nasal cavity
Maxillary Sinus Drains into the middle nasal meatus
Sinuses of the Skull

Sinus Drainage Pathways

Meatus Drainage
Superior meatus Posterior ethmoidal air cells
Middle meatus Anterior and middle ethmoidal air cells
Maxillary sinus
Frontal sinus (into the infundibulum)
Inferior meatus Nasolacrimal duct
Sphenoethmoidal recess Sphenoid sinus
Sphenopalatine recess Pterygopalatine fossa