Microanatomy and spatial analysis of the muscular triangle involving the vertebral artery’s third segment

PURPOSE: This study aims to characterize in detail the spatial relationships between the vertebral artery’s third segment (V3) and newly described posterior occipital muscle‑bounded triangles, and to evaluate the potential of combining multiple triangles for precise localization and exposure of V3. METHODS: Five cadaveric head specimens (ten sides) were subjected to layer-by-layer dissection to sequentially expose the subatlantic triangle (SAT), the superficial suboccipital triangle (SST), the deep suboccipital triangle (DST), the condylar triangle (CT), and the suboccipital triangle (SOT). VA within each triangle was visualized. The area of each triangle and the length of the VA exposed within each triangle were measured. RESULTS: The subatlantic triangle (SAT), superficial suboccipital triangle (SST), deep suboccipital triangle (DST), condylar triangle (CT), and suboccipital triangle (SOT) all allowed clear exposure of the vertebral artery. The horizontal segment length exposed by SOT was (10.81 ± 0.90) mm; the horizontal segment length exposed by CT was (5.89 ± 0.62) mm; the vertical segment length exposed by the SST triangle was (11.35 ± 1.22) mm; the vertical segment length exposed by the DST triangle was (15.56 ± 1.15) mm; and the vertical segment length exposed by SAT was (6.82 ± 0.72) mm. CONCLUSION: We propose the “SOT + CT double-triangle exposure” technique and the “SAT + SST+DST serial-exposure” technique as novel, non–bone landmark–dependent methods for localizing the horizontal and vertical segments of V3.