A 3-week-old infant presents with cyanosis that worsens with crying but improves with feeding (prone position). Examination shows choanal atresia. From which embryological structure does the choana normally develop?

• A Buccopharyngeal membrane
• B Fusion of the lateral nasal prominences
• C Dissolution of the nasal fin
• D Oronasal membrane perforation at week 7 ✓

Explanation

The nasal pits deepen to form nasal sacs that are initially separated from the oral cavity by the oronasal membrane. By the 7th week of embryological development this membrane ruptures to form the primitive choanae (posterior nasal apertures), establishing continuity between the nasal and oral cavities. Failure of this membrane to perforate results in choanal atresia — a bony or membranous occlusion of the posterior nasal aperture. Because neonates are obligate nasal breathers, bilateral choanal atresia is a neonatal emergency.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.