This lecture reviews the anatomy of the temporal bone including the microsurgical anatomy of the approaches directed through the middle fossa including the middle fossa approach to the internal acoustic meatus and the anterior petrosectomy approaches; the retrosigmoid approach to the CP angle and the internal acoustic meatus; and the lateral approaches directed through the mastoid including the retrolabyrinthine, translabyrinthine, and transcochlear approaches including the combined supra-infratentorial presigmoid variants of these approaches.