環椎後弓椎骨動脈溝の定量的研究―環椎後弓切除時における椎骨動脈損傷の予防

Quantitative Anatomical Study of the Vertebral Artery Groove on the Posterior Arch of the Atlas

　背景：環椎後弓切除時には椎骨動脈損傷を予防する必要がある．

　対象と方法：環椎後弓上面の椎骨動脈溝の定量的な観察を，晒骨を使用して行った．

　結果：正中から環椎後弓内側壁の椎骨動脈溝内縁までの距離は，最小値が左右ともに約7mmであった．この距離は全例で正中から環椎後弓外側壁の椎骨動脈溝内縁までの距離よりも小さかった．

　まとめ：環椎後弓の切除範囲は正中から左右に約7mmずつ，合計約14mmの範囲が安全域といえる．さらに，椎骨動脈を椎骨動脈溝から移動することにより，約25mmまで安全に後弓切除が可能となる．

　Background：This quantitative study was conducted from the standpoint of preventing vertebral artery injury during excision of the posterior arch of the atlas.

　Methods：We examined the vertebral artery grooves on the superior surface of the posterior arch of dry atlas specimens.

　Outcome：The minimum distance between the median line and the medialmost edge of the vertebral artery groove on the inner cortex of the posterior arch of the atlas was approximately 7 mm on both the right side and the left side, and it was shorter than on the outer cortex of the posterior arch of the atlas in every specimen.

　Conclusions：Thus, if the extent of the excision of the posterior arch of the atlas is approximately 7 mm from the median line on either side, the total safe area would be approximately 14 mm.　Moreover, mobilizing the vertebral artery on both sides from the vertebral artery groove would make it possible to safely excise the posterior arch up to approximately 25 mm.