Study On Applied Anatomy Of Jugular Foramen Region

Objective: To investigate the microsurgical anatomyof the jugular foramen(JF) and to confirm thecourse ,distribution and the relationship with theabut structure of the nerve and blood vessel of the JFand analyse the important structure quantitatively .to approach the protection and location mark of thenerve and blood vessel of the JF and provide an anatomicbasis for clinic surgery .Method: The JF of 12 antiseptic adult skulls weremicroanatomized with 5-times operation microscope ,the feature of the nerve and blood vessel of which andthe relationships with abut structures were observed .the JF of 12 dry adult skulls were measured to confirmedthe anatomy bone structure .Results: 1.The JF consist of three parts:pyramid inthe anterointernal which is made up of inferiorpetrosal sinus and glossopharyngeal nerve , parsnervosa in the medium which is composed of vagus nerveand accessory nerve , sigmoid part posterolaterally.2.The right JF was larger than the left in the maximumtransverse diameter of its endostoma and externalaperture,the same was in the external aperturedolichodiameter . There was no distinctive differencein the left and right the endostoma dolichodiameter.3. Glossopharyngeal nerve and vagus nerve can beseparated most easly in the JF endostoma in which theywere connected laxly;glossopharyngeal nerve was tiedwith internal carotid artery by a compact fiberbundle .4.Inferior petrosal sinus (IPS) drain amongthe glossopharyngeal nerve and vagus nerve or bleow theaccessory nerve and vagus nerve or into the internaljugular vein after inosculating with petrosa obliqueinfra vein into brachyvein . The IPS terminated injugular bulb in 50% case and internal jugular vein in33% case alone , in 17% case it came to jugular bulbinternal jugular vein with its two branchesseparately . 5. Jugular bulb had a very thin wall ,whichwas lesser than the half of that of the sigmoid sinusor internal jugular vein . the frequency of the jugularbulb was 12.5% . 6.The arteries in the JF includedposterior inferior cerebellar artery , anteriorinferior cerebellar artery;anterior inferiorcerebellavar artery (AICA) , ascending pharyngealartery and the branch of the occipital artery .theblood of the dura mater around the JF was suppliedmostly by the ascending pharyngeal artery . 7.Theinternal acoustic pore and the external aperture ofaqueduct of vestibule were located upper the JFendostoma;there were stylomastoid foramen in whichof the lateral the drum galact incisure was and styloidprocess in the lateral of the external aperture and theprocessus jugularis ossis occipitalis in the rear .suboccipital triangle was situated in the rear of thetransverse process of atlas . vertebral venous plexus ,1 neck nerve and vertebral artery were located in thetriangle . Lateral rectus capitis muscle originatedfrom superficies externa of the transverse process ofatlas and terminated in the superficies inferia of theprocessus jugularis ossis occipitalis . the styloidprocess was lied in the anterior aspect transverseprocess of atlas . the internal jugular vein which waslocated in the anteriomedialis of the internal jugularvein, vagus nerve , accessory nerve and hypoglossalnerve all cross between the transverse process of atlasand styloid process .Conclusion: 1.The JF was divided into petrosal part ,pars nervosa and sigmoid part . 2.The right JF waslarger than the left one in most case .the larger theJF was ,the riskier the operation was for bleeding .3.We should discriminate the rootlet of theglossopharyngeal nerve in the endostoma of the JF toreduce the incidence of misexsecting the vague nerve's rootlet and excising uncompletely when theglossopharyngeal neurotomy was done . 4.The inferiorpetrosal sinus terminated in not only jugular bulb butalso internal jugular vein alone or in branch . so weshould prevent bleeding by not blind excising . 5.Toconserve the integrity of the jugular bulb and controlthe bleeding effectively , we should have an intimateknowledge of the anatomic structure and keep asclerotin flake on the wall of the vein .it should becareful that the hemorrhoea caused by thesuperiorpositionjugular bulb happened when the operation wasdone through the os petrosum . 6.The arteries in theJF included posterior inferior cerebellar artery ,anterior inferior cerebellar artery;anteriorinferior cerebellavar artery (AICA) , ascendingpharyngeal artery and the branch of the occipitalartery .the blood of the dura mater around the JF wassupplied mostly by the ascending pharyngeal artery ,the meningeal branch of which provide the blood for thedura mater of the middle cranial fossa through thesphenotic foramen and for the posterior cranial fossathrough the JF or hypoglossal canal . 7.The anatomiclandmark that transverse process of atlas , Lateralrectus capitis muscle , digastric groove , processusjugularis ossis occipitalis , styloid processstylomastoid foramen and drum galact incisure etccontriute to identify the anatomy structure of the JF .8.It was a kind of microhurt method that the new growthin this area was revealed by opening the jugularforamen and carotid canal making use of the transverseprocess of atlas as the anchor point .On the whole ,it was advantage to protecting the nerve and vessel anduseful to reducing the incidence of the secondarydamage that the reasonable operative approach choosedaccording to the micro-dissection structure .