Applied anatomy of cranial base operation through petrous pyramid approach

Objective:To supply anatomic parameters for cranial base operation through petrous pyramid approach.Methods:Surface markers of temporal bone,the location and distribution of the important structures inside petrous pyramid concerning with cranial base operation were observed,measured and compared on 100 dry adult skulls,20 cranial base samples,15 cadaveric heads and 36 sides of CT films of normal adults.Results:The distances among superficial temporal bone markers helped to identify the location of sigmoid sinus and its upper and lower portions and the area of mastoid process that can be stripped during operation.The distances from posterior bony semicircular canal to anterior border of sigmoid sinus,from the labyrinth to facial nerve,from internal carotid artery to superficial markers on the petrous pyramid were helpful to identify and protect the labyrinth,facial nerve and internal carotid artery.When conducting operation through middle cranial fossa,the arcuate eminence can be taken as a marker for identifying upper bony semicircular canal while internal acoustic meatus and the hiatus of greater petrous nerve as a marker for unmasking of geniculate ganglion,the labyrinth and the fundus of internal acoustic meatus.When stripping substantial ossea of petrous pyramid,the line from posterior wall of carotid canal to posterior border of internal acoustic pore was the terminal line.Conclusions:The distances among superficial temporal bone markers and the location of important structures inside petrous pyramid may supply important references for cranial base operation through petrous pyramid approach.