The lateral skull base constitutes an anatomic boundary between the fields of neurosurgery and otolaryngology.

Surgery in this region has always been a challenge for both disciplines owing to the presence of important anatomical structures such as the internal carotid artery, the otic capsule, and the facial nerve.

Several approaches have been developed to reach pathology located in the lateral skull base and in the fundus of the internal auditory canal (IAC) and petrous apex.

Despite the benign nature and limited dimensions of the lesions located in this anatomical region, extensive surgical approaches are often required to reach and remove the disease.

At present the main application of endoscopic surgery relies on the middle ear cholesteatoma surgical treatment, but in the natural evolution of the technique there are the steps forward of lateral skull base surgery and petrous bone pathology.

During the experience of recent years, we progressively noticed that the internal ear and the whole temporal bone could be accessed in an endoscopic assisted fashion or even by exclusive endoscopic approaches. Despite the benign nature and limited dimensions of lesions located in this anatomical region, extirpative surgical approaches are often required to reach and remove the disease The problem would only be to codify as much as possible the landmarks and the procedures, and to integrate them to classic microscopic approaches.

Three main corridors to the lateral skull base were identified: the transcanal suprageniculate corridor, the transcanal transpromontorial corridor, and the transcanal infracochlear corridor.