From the Research
The embryology of each paranasal sinus involves a complex and sequential development, with the maxillary sinuses appearing first around the 10th week of gestation, followed by the ethmoid, frontal, and sphenoid sinuses, with all sinuses reaching their adult size by late teens to early twenties. The development of paranasal sinuses can be broken down into the following stages:
- Maxillary sinuses: develop first, around the 10th week of gestation, as small outpouchings from the middle meatus of the nasal cavity, and remain relatively small until after birth, then undergo two growth spurts: one between ages 0-3 years and another during puberty 1.
- Ethmoid sinuses: begin as evaginations from the lateral nasal wall around the 12th week of gestation, forming anterior, middle, and posterior ethmoid air cells, and are the only sinuses present at birth, though still underdeveloped 2.
- Frontal sinuses: develop from anterior ethmoid cells that migrate upward into the frontal bone, typically beginning around 2 years of age and continuing development through adolescence 2.
- Sphenoid sinuses: originate from posterior ethmoid cells that invade the sphenoid bone around the 4th fetal month but remain small until significant expansion occurs after 3 years of age 2. This sequential development is supported by the most recent and highest quality study, which provides a comprehensive review of the physiology, development, and imaging anatomy of the maxillary sinus 3. Some key points to note about the development of paranasal sinuses include:
- The maxillary sinus begins its development at the 10th week of gestation and undergoes significant growth after birth 1.
- The ethmoid sinuses are present at birth, but are still underdeveloped, and continue to grow and develop throughout childhood and adolescence 2.
- The frontal and sphenoid sinuses develop later, with the frontal sinuses beginning to develop around 2 years of age and the sphenoid sinuses expanding significantly after 3 years of age 2.
- All sinuses continue to develop and grow throughout adolescence, reaching their adult size by late teens to early twenties 2.