The lateral13 of the external auditory canal is a cartilaginous external auditory canal based on the cartilage of the external auditory canal, and the medial 2/3 is a bony external auditory canal based on bones. The connection between them is very narrow; The stenosis is about 2cm away from the external auditory canal, and the narrowest part of the external auditory canal is called isthmus, which can prevent foreign bodies from entering the external auditory canal and invading the tympanic membrane. External auditory canal cartilage and auricle cartilage are continuous. When examining the tympanic membrane in clinic, lifting the auricle upward and backward can straighten the external auditory canal and facilitate observation.