What is the fate of the first pharyngeal cleft?

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Study for the Pharyngeal Apparatus Test. Dive into multiple choice questions with detailed explanations and hints. Prepare effectively for your exam!

Multiple Choice

What is the fate of the first pharyngeal cleft?

Explanation:
The first pharyngeal cleft becomes the external auditory canal. This cleft is an ectoderm-lined groove between the first and second pharyngeal arches, and it persists as the canal that extends from the tympanic membrane outward to the external ear opening. The tympanic membrane itself has an outer surface from the ectoderm of this cleft and an inner surface from the endoderm of the first pharyngeal pouch, which also gives rise to the middle ear cavity and the pharyngotympanic (eustachian) tube. The other clefts are largely obliterated by overgrowth of the second arch, forming the cervical sinus, so they do not become the external auditory canal.

The first pharyngeal cleft becomes the external auditory canal. This cleft is an ectoderm-lined groove between the first and second pharyngeal arches, and it persists as the canal that extends from the tympanic membrane outward to the external ear opening. The tympanic membrane itself has an outer surface from the ectoderm of this cleft and an inner surface from the endoderm of the first pharyngeal pouch, which also gives rise to the middle ear cavity and the pharyngotympanic (eustachian) tube. The other clefts are largely obliterated by overgrowth of the second arch, forming the cervical sinus, so they do not become the external auditory canal.

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