The Study On The Surgery Anatomy Of The Extracranial Soft Tissue Structure In Suboccipital Far-lateral Approach

Objective The purpose of this study is to explore the surgery anatomy of the extracranial soft tissue structure in suboccipital far-lateral approach. It can provide more applied anatomic data for clinical practice, and to decrease surgical complications. Methods Ten (twenty sides) formalin fixed adult cadaveric head including necks whose arteries and veins had been injected with colored latex were imitated the suboccipital far-lateral approach. We dissected the extracranial soft tissue structure in suboccipital region, observed the courser and the mutual structural relationship of the muscles, proximal vessels and nerves in suboccipital region and measured the distance between the transverse foramen of atlas and the transverse foramen of axis, the diameter of the vertebral artery in suboccipital region, the distance between superior margin of the transverse foramen of atlas and the point which the vertebral artery across the dura and the distance between inner margin of the point which the vertebral artery across the dura and the posterior margin middle point of the foramen magnum.Results1. The triangulum which surrounded by the obliquus capitis superior, obliquus capitis inferior and rectus capitis posterior major is suboccipital triangle. The vertebral artery pass through the deep layer of suboccipital triangle.2. The ventral branches of 2nd cervical nerve permanently stride the pone of the vertebral artery which located between the atlas and axis.3. The venous plexus beside the vertebral artery are affluent and irregular in suboccipital region. The closer they get to the center part, the smaller the venous plexus from the transverse foramen of atlas to the point which the vertebral artery across the dura. The vertebral artery is circumvolutio by the venous plexus between the transverse foramen of atlas and the transverse foramen of axis. The venous plexus are more and more dense from bottom to top.4. The transverse foramen of atlas located in the superolateral of the transverse foramen of axis, the distance between the two transverse foramen is (17.82±3.65) mm.5. The distance between superior margin of the transverse foramen of atlas and the point which the vertebral artery across the dura is(33.29±7.79)mm.6. The vertebral artery is circuitous and changeable in suboccipital region, the distance between inner margin of the point which the vertebral artery across the dura and the posterior margin middle point of the foramen magnum is (24.85±2.96) mm.7. In most cases, the occipital artery walks across the inferior of the longissimus capitis. But if the occipital groove is absent, the artery will walks across the inferior of superficial layer splenius capitis to the longissimus capitis muscle.Conclusions1. The suboccipital triangle, ventral branches of 2nd cervical nerve and the venous plexus beside the vertebral artery are the important landmarks to search the vertebral artery in the suboccipital far-lateral approach.2. In the suboccipital far-lateral approach it can enlarge the exposed circumscription by drill the transverse process of atlas and excise at least half of the posterior arch of atlas, isolating and removing the vertebral artery to endo-inferior, and excise part of the occipital condyle and the massa lateralis atlantis on the posterior and inner if it is necessary.3. The study on the surgery anatomy of the extracranial soft tissue structure in suboccipital far-lateral approach can improve the safety of this approach and the therapeutic effect of operation, and to decrease surgical complications.