Variation of the Great Auricular Nerve and Prediction of the Facial Nerve Trunk Size

Background: This study aimed to reveal the anatomical variation in the great auricular nerve (CAN) and the correlation between the size of the CAN and the facial nerve trunk (FNT), so as to aid surgeons to perform safe facelift surgery and patotidectomy. Methods: Sixteen human cadavers were studied on 16 left and 15 right facial sides. The GAN's branching patterns, location, and the mean width of the GAN and FNT were measured. Results: The average distance where the nerve emerged from under the sternocleidomastoid muscle was 87.61 +/- 12.13 mm when measured perpendicular to the Frankfort horizontal plane. The branching pattern of the GAN could be classified into 7 types of which the most common was type 3 (30.77%), where the CAN divided into the anterior (superficial) and posterior branches, and then the deep branch originated from the posterior branch of the CAN. The mean width of the CAN and FNT from all the dissections was 3.26 +/- 0.67mm and 3.36 +/- 0.71 mm, respectively. There was a significant correlation between the width of the nerves on both facial sides (right: r =0.710, P=0.002; left: r = 0.839, P< 0.001). Conclusions: This study revealed the anatomical variation and the width of the GAN, which can strongly piedict the width of the FNT. This should be taken into consideration during facelift surgery and parotidectomy, especially in patients with a small CAN to prevent iatrogenic injury to the small FNT.