Investigation On Localization And Reservation Of Accessory Nerve In The Modified Radical Neck Dissection

Objective: To make a retrospective analysis about the modified radical neck dissection, and explore the anatomic location and reservation of the accessory nerve in modified radical neck dissection.Material and methods: From October 2007 to March 2009,a retrospective analysis was performed with 178 cases (201sides)of modified radical neck dissection in the Qilu Hospital of Shandong University, correlations between the accessory nerve and the surrounding structures were measured and recorded, meanwhile,the method, in the Qilu Hospital of Shandong University,of the Search location dissection and reservation of the accessory nerve were observed and recorded.Result: The accessory nerve goes out of inferior border of the posterior belly of digastric muscle , crosses by anterior surface and posterior surface of the internal jugular vein in 56%(112/201) and 44%(89/ 201)of the patients respectively . then,going through or beneath the sternocleidomastoid occurred in 81%(163/201) and 19%(38/201) of the patients respectively. The distance from the mastoid process to the point where the accessory nerve enters the sternocleidomastoid is (5.03±0.85) cm; The distance from the point where the accessory nerve emerges the sternocleidomastoid to the point where the great auricular nerve emerges the sternocleidomastoid is (1.01±0.49) cm; the accessory nerve is paralleled the anterior boeder of the trapezius muscle before it entered the muscle in 64%(128/201), and 36%(73/201) angularity. The distance from the point where the accessory nerve emerges the trapezius muscle to the middle point of clavicle is (4.77±0.82) cm. There is no significant difference between the data get from men and women or left and right neck. Conclusion: there are three points helpful in locating the accessory nerve: anterior border of the sternocleidomastoid,where it is 5cm to the mastoid process ; posterior border of the stemocleidomastoid, where it is within 2cm upper to the point where the great auricular nerve emerges the stemocleidomastoid ; the anterior boeder of the trapezius muscle where it is about 4-5cm to the middle point of clavicle;but in the modified radical neck dissection,they are not completely useful. in the Qilu Hospital of Shandong University,we look for the accessory nerve usually on anterior boeder, upper proximal third point of the sternocleidomastoid,there is some connective tissue within some small vessels located ,under which,we can find out the accessory nerve easily and quickly. Another point for looking for easily is posterior border of the stemocleidomastoid, where it is within 2cm upper to the point where the great auricular nerve emerges the stemocleidomastoid ; However,at the anterior boeder of the trapezius muscle; it is difficult to find out he accessory nerve in modified radical neck dissection.