Review Question - QID 210046

A 4-year-old boy is brought in to his pediatrician by his mother because of several days of fever, irritability, and ear pain. His mother says that she was particularly concerned about his complaints of difficulty hearing and dizziness. Physical exam reveals a bulging tympanic membrane. As the pediatrician does the examination, she explains to the medical student accompanying her that the lining of the infected area is derived from the endodermal component of a certain embryological structure. The mesodermal component at the same level is most likely responsible for the development of which of the following structures?