Which pharyngeal membrane forms the tympanic membrane?

Which pharyngeal membrane forms the tympanic membrane?

• A. First pharyngeal membrane
• B. Second pharyngeal membrane
• C. Third pharyngeal membrane
• D. Fourth pharyngeal membrane

Answer: (A)

The tympanic membrane is formed from the first pharyngeal membrane, which is the boundary between the first pharyngeal cleft (outside ear) and the first pharyngeal pouch (middle ear). Its outer surface is derived from ectoderm of the cleft, the inner surface from endoderm of the pouch, and the middle fibrous layer comes from the mesenchyme of the first pharyngeal arch. Because this boundary specifically links the external auditory canal and the middle ear, the first pharyngeal membrane is the source of the tympanic membrane, while the other pharyngeal membranes contribute to different structures and do not form it.

The tympanic membrane is formed from the first pharyngeal membrane, which is the boundary between the first pharyngeal cleft (outside ear) and the first pharyngeal pouch (middle ear). Its outer surface is derived from ectoderm of the cleft, the inner surface from endoderm of the pouch, and the middle fibrous layer comes from the mesenchyme of the first pharyngeal arch. Because this boundary specifically links the external auditory canal and the middle ear, the first pharyngeal membrane is the source of the tympanic membrane, while the other pharyngeal membranes contribute to different structures and do not form it.