Detailed knowledge of the surgical anatomy of the cerebellopontine angle (CPA) is vital for surgical treatment of CPA tumors and vertebral artery (VA) aneurysms and for microvascular decompression (MVD) surgeries [4, 7, 8, 11, 13, 18–20, 23]. CPA is a cistern that is surrounded by the petrous bone laterally and the petrosal (lateral) cerebellar surface and brainstem medially. Many cranial nerves (CNs), arteries, and veins run in this cistern [17]. First, the lateral and medial walls of CPA will be described; later, CNs and vessels, especially the basic relationships between nerves and arteries, will be explained. The microsurgical anatomies of the internal acoustic meatus and lateral part of the foramen magnum are described in detail in Chaps. 14 and 17, respectively. The microsurgical anatomy and surgeries for MVD are described in Chaps. 10– 13.
