Where are pharyngeal membranes located?

• A. Where the pharyngeal pouches meet the clefts.
• B. Inside the first pharyngeal arch.
• C. On the exterior surface of the embryo.
• D. Between the pouches and the arches.

Answer: (A)

Pharyngeal membranes form at the boundary where a pharyngeal pouch (endoderm) meets the pharyngeal cleft (ectoderm). This junction—the contact between pouch and cleft—is where the thin membrane develops, and the first pharyngeal membrane specifically gives rise to the tympanic membrane. So the location described as where the pharyngeal pouches meet the clefts is the correct understanding. It isn’t inside the pharyngeal arches, nor on the exterior surface of the embryo, nor between the pouches and arches, since membranes are the junctions between pouch and cleft, not within arches or at other interfaces.