The Studies Of The Microdissection Associated With The Retrosigmoid Approach And Retrosigmoid-Suprameatal Approach

To explore the microdissection of the cerebellopontine angle(CPA) as well as to study the advantage and disadvantage of the retrosigmoid approach(RSA) and the retrosigmoid suprameatal approach (RSSMA), the relationship among the facial nerves, inter-medium nerves, anterior inferior cerebellar artery(AICA) and petrosal vein were studied, and two approaches particularly also were explored from fifteen dry skulls and ten wet skulls, along the approach of RSA and RSSMA. The results were as follows:1. The facial nerves, whose length of CPA was 11.13±1.35mm and the length of internal auditory canal was 10.69±0.90mm. From the brain stem at the lateral end of ponto medullary sulcas, the distance between the facial nerve, the vestibulocochlear nerve, the abducenst nerves, and the trigeminal nerve were 2.38±0.65mm, 6.62±0.41mm, 7.59±1.08mm. The facial nerves and vestibulocochlear nerve could be seen at the inner front part of 32 mm from the intersection endo-anterior.2. There were one-rootlet of the inter-medium nerves in twelve sides, two in six samples and three in two sides. No four-rootlet were found. The vestibular portion was 7.62±0.69mm long, the intermediate space was 10.05±1.12mm.3. The frequency of AICA was 100%. There were twenty-three in twenty CPAs, single stem in eighteen CPAs and duplicate stem in one CPAs, tristem in one CPA. There were twenty stems originated from the inferior segment of basal artery, two of which were from the intermediate piece and one from the superior segment. The appearing of Para-AICA was three. The main branch of the AICA was labyrinthine...