Paranasal sinuses – normal maturation

Maxillary sinus

• first to develop.
• rudimentary at birth.
• 2mm/year growth rate in vertical dimension
• growth till end of puberty
• 1 year: lateral margin of sinus projects under medial orbital wall.
• 4 years: extends laterally past infraorbital canal.
• 9 years: reaches maxillary bone and plane of hard palate

Ethmoid sinuses

• at birth: developed anteriorly more than posteriorly.
• lack of pneumatization of posterior ethmoids – normal till 6 years.
•  eventually posterior ethmoid air cells larger and fewer than anterior.
• last to develop – agger nasi, Haller and concha bullosa.

Sphenoid sinuses

• soon after birth, begin to pneumatize; as early as 2 years.
• pneumatization proceeds inferiorly, posteriorly and laterally.
• first presphenoid, followed by basisphenoid, greater wings and pterygoid processes.

Frontal sinuses

• last to develop.
• extensions of anterior ethmoid air cells.
• earliest at 2 years in the orbital processes of frontal bone
• 4 years: nasion
• 8 years: orbital roof.
• 10 years: vertical portion of frontal bone.
• growth till end of puberty.