Microanatomy Research Of Position Relation Of â…§ Cranial Nerve And Neurovascular Around In Cerebelloponotine Angle

The anatomic structures of the cerebellopontine angle(CPA) are complex,it includes life centre and many crucial neurovascular structures such as brain sterm,cranial nerves,autery and vena.?Ⅷcranial nerve derives from brain sterm and enters internal auditory canal via CPA in posterior cranial fossa.It is adjacent to many vital cranial nerves and blood vessles.Hearing disturbance is often occurs in the operation in CPA.For this reason,it is of the utmost importance for we to comprehend the position relation ofⅧcranial nerve and the neurovascular around for clinic surgery operation.Objective : To observeⅧcranial nerve and the neurovascular around and discribe the position relation of them via retro sigmoid approach under binocular microscope;To observe and measure them after remove the scalvaria and part of cerebellum;To observe the blood vessles and the branches behind the brain sterm after remove the brain sterm.To provid the anatomical basis to reduce the injury ofⅧcranial nerve and blood vessles which correlate to it in opration in CPA.Methods: to get 15 adults cadaveric heads which are thoughly soaked in formaldehyde solution (all are male).Step dissect the cadaveric heads vio retro sigmoid approach . observeⅧcranial nerve and the neurovascular around under binocular microscope.Saw the skull and remove the cerebrum and open the tentorium of cerebellum.observe and measure the position relation ofⅧandⅤ,Ⅵ,Ⅶ,Ⅸcranial nerves, AICA (Anterior inferio cerebellar artery), PICA(Posterior inferior cerebellar artery) and other adjacent cranial nerves and blood vessles.Remove the cerebellum and observe the slight artery such as IAA(internal auditory artery) and PRA(recurrent perforating artery) etc.Results : (1)In the CPA, the length ofⅧcranial nerve is (6.85±2.67)mm,Ⅶcranial nerves is (9.96±2.93)mm.The diameter ofⅧcranial nerve at the entrance of the internal acoustic meatus is (2.38±0.22)mm,Ⅶcranial nerves is (1.53±0.16)mm.The distance ofⅦandⅧcranial nerve where they jion the brain stem(all are nearest followed) is (2.23±0.21)mm.Ⅴcranial nerve lies in the intra-anodic ofⅦcranial nerve about (4.98±1.82)mm,Ⅵcranial nerve lies in the intra-anodic ofⅦandⅧcranial nerve about (8.69±0.55)mm.The start point ofⅧcranial nerve is about (6.02±0.49)mm away from the position whichⅨcranial nerve joins the brain sterm,and the distance of the two nerves at the position where they enter the crinial bone is about (3.68±0.52)mm。The caliber of AICA nearⅧcranial nerve is about (1.26±0.33)mm,the caliber of PICA is about (1.26±0.33)mm and VA is about (3.09±0.50)mm。(2) AICA andⅦ,Ⅷcranial nerve are in close relations,espesiallyⅧcranial nerve.The percentage of the probability of AICA contacts withⅧcranial is 38% and theⅦcranial is 36%.AICA is mostly sterm from BA(Basilar artery)(28CAPs), PICA is mostly sterm from VA(26CAPs). (3) IAA is mostly sterm from the lateral branch(A1) of AICA, PRA is mostly sterm from the medial branch(A2) and jions VA finally.Conclusions : The prehension of the vital anatomic structure ofⅦ,Ⅷcranial nerves and AICA is beneficial for us to preserve the anatomical and functionality integrity of related cranial nerves and blood vessles.So it have vital significant for microsurgery in CPA.