Far-lateral Transcondylar Approach to the Posterior Cranial Fossa:Stereoscopic Microsurgery and Applied Anatomy

Objective To provide a basis for applied anatomy and stereoscopic structure in far-lateral transcondylar approach to the posterior cranial fossa,and thus protect vital structure,make the microneurosurgery easier,and enhance the safety of the operation.Methods Microsurgical anatomy and measurement were performed on both sides of 10 adult skulls according to the procedures of this approach.The measurement data of foramen magnum were analyzed statistically.Results Mastoid process,styloid process,stylomastoid foramen,lateral tip of the transverse process of atlas,jugular fossa,occipital condyle,and external occipital protuberance were important anatomical markers.Inferior occipital triangle formed by rectus capitis posterior major muscle,obliquus capitis superior muscle,and obliquus capitis inferior muscle was an important anatomical marker in far-lateral transcondylar approach.The base of the inferior occipital triangle consisted of posterior atlantooccipital membrane and posterior arch of atlas,and the major structures around it were vertebral artery,atlanto-occipital joint,sigmoid sinus,jugular foramen,posterior lacerate foramen,and post-group cranial nerve.The vertebral venous plexus and cervical nerves Ⅰ and Ⅱ should also be noticed.The distance and three-dimensional structure among the main markers were measured and analyzed.Conclusion It is helpful to know the important procedures and adjacent and three-dimensional structures and then choose the appropriate surgical approach according to the lesions located in different positions during the process of far-lateral transcondylar approach to target region.This approach can preserve the important structure effectively and safely.