[SUMMARY] 【Background】In the neurosurgical procedures, dural sinus injury is a devastating complication during craniotomy. Recent development of neuroimaging offers identifying a position of the dural sinus quickly and accurately using intraoperative navigation systems. However, the establishment of a simple method based on anatomical landmarks is still useful, when intraoperative navigation systems are unavailable. Therefore, we evaluate the usefulness of muscle insertion line （the superior nuchal line : SNL） as a landmark to identify the transverse sinus using contrast-enhanced 3-dimensional computed tomography（3DCT）. 【Method】This retrospective review included 52 patients who underwent posterior cranial fossa surgery between January 2018 and December 2019. We evaluated the relation between SNL and the transverse sinus at 3 points on 3DCT （midline, right side, left side）. 【Results】 SNL placed caudally to the transverse sinus is 38.5％（20/52 cases） at midline, 55.0％（28/51 cases） at the right side, and 27.1％ （13/48 cases）at the left side, respectively. SNL placed on the transverse sinus is 40.4％ （21/52 cases） at midline, 29.4％ （15/51 cases） at the right side, and 29.2％ （14/48 cases） at the left side, respectively. SNL placed rostrally to the transverse sinus is 21.2％ （11/52 cases） at midline, 15.7％（8/51 cases） at the right side, and 43.8％（21/48 cases） at the left side, respectively. 【Conclusions】The identification of SNL and the transverse sinus using contrast-enhanced 3DCT provided a useful and straightforward method to avoid venous sinus complications for posterior cranial fossa surgery.

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