The pyramidal eminence, the bony portion of the Eustachian tube, the semicanal of the tensor tympani muscle, and the cochleariform process were visualized completely or partially in all cases. Principle behind air insufflation otoscopy (Pneumo-otoscope). According to its position in relation to the round window, the fustis was classified into type A (68.9%) or B (31.1%). External auditory canal is very sensitive. Of the 45 MEs evaluated, type A was predominant for finiculus (93.3%), subiculum (100%), and ponticulus (95.6%). The facial canal was open and protruding in 15/45 (33.3%) and in 7/45 (15.5%) specimens, respectively. Ossicles were seen in 13/45 (28.8%), stapes at the oval window were seen in 12/45 (26.6%), and the incus was seen in 1/45 (2.2%) specimens. The endoscopic anatomy of the middle ear (ME) and of the external acoustic meatus (EAM) has been described in cadavers, in fresh temporal bones, or in vivo. The anterior wall of the EAM was prominent in 10/48 specimens (20.8%). Out of 50 specimens, 2 had exostosis of the EAM and 3 contained remains of the tympanic membrane. The EAM and the ME were studied in dry temporal bones using an endoscopic transcanal approach with a telescope connected to a smartphone (M-scope mobile endoscope app and adaptador, GBEF Telefonia, São Paulo, SP, Brazil). To study the anatomy of the ME and of the EAM in dry temporal bones using a smartphone-endoscope system. Foreign bodies impacted at this point could be removed by use of aural hook, using the potential space at the superior portion of the isthmus.The endoscopic anatomy of the middle ear (ME) and of the external acoustic meatus (EAM) has been described in cadavers, in fresh temporal bones, or in vivo using conventional video recording, but not in dry bones or using an alternative inspection and recording technique. This is mainly an anteroposterior narrowing and is oval or inverted pear shaped. Conclusions: The isthmus is a bony-cartilaginous junction, and the narrowest point of the EAM is situated at the junction of the outer one third of the inner two thirds of the canal length. The cross-section of this area was either an inverted pear or oval shape. This narrowing was 5.7 (range 3–7) mm wide in the anteroposterior plane, but 8.2 mm (range 6.5–10) mm wide in the vertical plane. The isthmus corresponds to the bony and cartilaginous junction, which is traditionally thought to be narrowed by the canal angulation. The mean canal length was 27.7 (range 20–34.8) mm. Results: The narrowest point of the EAM, i.e., the isthmus, was located at the junction of the medial two thirds (mean 17.9 mm) to the lateral one third (mean 9.8 mm) of the canal. The measurements of the impressions were done by using a micrometer (Vernier caliper), calibrated to 0.1 mm. All abnormal ears were excluded from the study. Materials and Methods: Twelve impressions were taken from 8 adults. This study was designed to determine the location and cross-sectional shape of the narrowest point of the EAM, i.e., the isthmus, by using silicone casting material in human cadaver ears. A foreign body is more likely to be stuck at the narrowest point of the EAM. Objective: Foreign bodies are commonly impacted in the external auditory meatus (EAM), and removal is sometimes difficult due to the tortuous anatomy.

External acoustic meatus