The Clinical Anatomy Research In Lateral Skull Base Regions Of Human Adults

ObjectiveThe tumors of the lateral skull base often had deep localization .With vital structures such as cranial nerves , arteries and veins neighboring, traditional operations whether the occlusalf surface approach or the cranium approach, not only had damage to physiognomy, but also the complications and the death rate were high.With difficulties in exposure and dissection the tumor completely of the operation, the recurrence rate was also high. Thus, the operation in lateral skull base was once deemed to be restricted zone. In recent years, with developments in the subjects of medical imageology, anesthesia, critical care medicine and the micro-surgery of the ear, the diagnosis and treatments of the lateral skull base had also developed greatly. Our research was based on the observation and measurements of the important anatomical markers in the lateral skull base. With corresponding anatomical data arrived, we hope these results can provide anatomical guidance in the clinical surgeries: to expose operating field better; avoid the damage to important vessels,nerves and prevent excessive dragging ;design the best project of the re-establishment in the skull base when the tumors were dissected; in the endoscopic lateral skull base surgery, it can ensure the safety as well as decrease the possibility of the errors in the navigation and the localization.Methods20 heads with 40 sides of the lateral skull base of dead body with 10% formaldehyde soaked, which includs 12 male, 8 female.(the information of the gender and the age were provided by the anatomy department). Then these sides of the lateral skull base had a serial number from 1st to 40th.The cadaveric heads was fixed in the anatomical shelf . The calvaria was removed alone the plane parallel to the frankfort horizontal plane in the middle super point of the line between the root of zygomatic bone and the highest point of parietal bone.The structure in the skull base was observed and measured.Dissect the mandible and its affiliated muscles and the structure out the skull base was observed and measured. Skeletonize the mamillary process by electrodrill with its supra-boundary to cerebral dura mater of the middle cranial fossa, and expose sinus-menigeal angle, the lateral, anterior and posterior semicircular canals, the whole range from sigmoid sinus to bulbus venae jugularis , the omnidistance of the facial nerve from Intracalvarium to extratemporal segment. Dissect the carotid artery in the neck till the external aperture of the internal carotid artery was found. Drill the sclerotin with the diamond burr to expose the internal carotid artery's os petrosum section, while of the Intracalvarium, internal carotid artery was exposed to the superior part of the anterior clinoid process.ResultsThis research includes three contents:①The asterion, and the vein and the nerve of the bony jugular foramen as well as the dorsal root of the zygomatic arch and the styloid process were set as the base of the anatomy, then observe the anatomical relationships, distances and the angles of the important structures in the lateral skull base.②Measure the areas of the labyrinthine triangle(sino-meninges angle, jugulotympanic body , aditus ad antrum tympanicum) , retrolabyrinthine triangle(sino-meninges angle, jugulotympanic body, posterior semicircular canal) and the triangle of the surface of mastoid process(asterion, mastoidle, Zygomatic root).③Measure the length of different segements of facial nerve in temporal bone; Measure the extended extracranial portion to provide anatomic data for repairing the facial nerve defect with extended facial nerve gotten by changing its course in temporal bone.Measure the distance and angles of the initiative anterior rerouting of the facial nerve, with it's long-pathway(from foramen stylomastoideum to geniculate ganglion) and short-pathway(from foramen stylomastoideum to external genu).Analyze the metered parameters by the SPSS 10.0 statistics software and demonstrate the measurement data by the mean±root-mean square deviation ( (x|-)±s) .Conclusions1. This antomic investigation by imitating operations, with thoughts of the clinical surgery, may provide an advisable reference and guidance to the clinical operations .2. The jugulotympanic body had frequent variation, while the variation of the vein of the bony jugular foramen was uncommon. This research had set the bony part of the jugular foramen as basic point to measure the distances with bony markers, this may bring us more accurate results and decrease the possibility of the damage to the jugulotympanic body during the operation. And set the nerve part of the jugular foramen may provide the guidance and reference to protect the lower cranial nerves more effectively during the operation.3. The arrived anatomical data, which were set by the basic point of the styloid process and the zygomatic root, as well as the asterion, can not only decrease the risks of the damage to the nerve and vessels during the operation, but also ensure the safety of endoscopic surgery, decrease the mean fiducial registration errors in the image-guided navigation on the lateral skull base.4. The metered areas of labyrinthine triangle, retrolabyrinthine triangle and the triangle of the surface of mastoid process may provide guidance and reference to the reconstruction of the lateral skull base as well as the choice of the surgical approaches.5. The length of facial nerve stem can be extended in temporal bone by changing its course.It is applicable to repair the facial nerve defect in the lateral skull base surgery through extending the length of facial nerve; Extensive visual field of the operation was also provided by the initiative anterior rerouting of the facial nerve.Before anterior transposition is performed,the nerve has to be liberated in the parotid grand.A nontoothled forceps was used to hold the soft tissue surrounding the stylomastoid foramen,and anterior rerouting was carried out.