Cervical vagus nerve morphometry and vascularity in the context of nerve stimulation - A cadaveric study

Figure 1. Paraffin-embedded axial-plane section on level of C5 vertebral body. M = midline distance (lateral distance between the laryngeal prominence and the cervical vagus nerve), S = skin distance (anterior-posterior distance between the skin surface and the cervical vagus nerve in sagittal direction), l = left, r = right.

Figure 2. Topography of the neck region. The interrupted line indicates the level at which the cervical vagus nerve was visualized (A) on the level of the laryngeal prominence. Vessels external to the epineurium were observed in 25/51 cases (blue arrows, B). a = anterior, cd = caudal, cr = cranial, p = posterior.

Figure 3. Hematoxylin-eosin stained histology sample of the cervical vagus nerve. A number of fascicles can be seen, separated by perineurium. Subepineural vascular supply could be observed (arrows), as well as subperineural supply (magnifications on left side). *Artefact introduced by the processing of the sample.

Figure 4. Box plots of cervical vagus nerve morphometry and surface anatomy. Darker grey boxes indicate the 25% percentile, the solid black line the median, the lighter grey box the 75% percentile, and the hatched are the 95% percentile. Whiskers show the minima and maxima. (A) Nerve morphometry, (B) Nerve relations to the skin surface (skin distance) and laryngeal prominence (midline distance).

Figure 5. Cervical vagus nerve fascicle and vessel number (A) and vessel diameters (B). Darker grey boxes indicate the 25% percentile, the solid black line the median, the lighter grey box the 75% percentile, the whiskers minima and maxima. Significant differences were observed comparing the number as well as the minimum and maximum diameters between subepineural and subperineural vessels. The grey numbers on top give the numerical maximum.

Figure 6. (A) Comparison of vessel diameters between cervical vagus nerves with external vessels (relative to the epineurium) showing significant differences. Darker grey boxes indicate the 25% percentile, the solid black line the median, the lighter grey box the 75% percentile, the whiskers minima and maxima. (B) Comparison of the maximum diameter of subperineural vessels between sexes and sides, showing both significant differences. Darker grey boxes indicate the 25% percentile, the solid black line the median, the lighter grey box the 75% percentile, the whiskers minima and maxima. The grey numbers on top give the numerical maximum.