Study of microsurgical anatomy for far-lateral transcondylar approach

Objective To study the basic microsurgical anatomy parameters for the far-lateral transcondylar approach and to protect the vital structure around foramen magnum.Methods Fifteen dry skulls and twenty formalin fixed adult cadveric heads were employed by microsurgical dissection.Results Occipital condyle (OC) was an important sign and its long axis was 24.47±3.32 (18.19~30.30) mm (left, L) and 25.16±2.39 (20.66~29.02) mm (right, R). The distance from the posterior midline of the foramen magnum (FM) to the medial border of the OC was 27.66±2.45 (23.00~31.48) mm (L) and 26.27±1.83 (23.68~29.64) mm (R). Inferior occipital triangle was formed by three muscles, which was rectus capitis posterior major, superior oblique and inferior oblique. The structures in the triangle were the vertebral artery, muscular branches, vertebral venous plexus and C1 nerve. The distance of vertebral artery from lateral side of transverse foramen of atlas to its dural entry was 16.87±2.08 (12.64~20.1) mm (L) and 16.79±1.90 (12.44~20.22) mm (R).Conclusion It is highly important that the anatomic parameters were measured for the far-lateral transcondylar approach.