Morphological Study of the Great Auricular Nerve and Adjacent Structures by Ultrasound Imaging and Transcutaneous Nerve Stimulation

Ultrasound-guided nerve block has the characteristics of high success rate, few complications, and high patient satisfaction. It has been widely used in brachial plexus and lumbar plexus nerve blocks. Studies of ultrasound-guided superficial cervical plexus block are mostly unsatisfactory, and may be due to anatomic localization of the puncture site rather than real-time ultrasound guidance. The great auricular nerve is the largest branch of the superficial cervical plexus and may be identified under ultrasound. The aim of this study is to establish the success rate of identification of the great auricular nerve by combining ultrasound imaging with transcutaneous nerve stimulation. In addition, we will study the relationship between the success rate of identification and the related factors of patients. Another purpose of this study is to locate the position where the great auricular nerve emerges the posterior border of the sternocleidomastoid muscle. The relationship between this point and the midpoint of posterior border of the sternocleidomastoid muscle and adjacent structures will also be studied.