| Objective: Through the anatomy of the recurrent laryngeal nerve(recurrentlaryngealnerve,RLN),especially the entry of RLN into the larynx,to measure the relevant data of the entry of RLN into the larynx,to understand the spatial location of the entry of RLN into the larynx,to provide meaningful reference marks and data for clinical thyroid surgery,and to reduce the damage to RLN during thyroid surgery.Methods: Excluding the cadavers with history of neck surgery,thyroid lesions and amputation of RLN,40 male adult cadavers fixed with formaldehyde,aged from 18 to 60 years old,both RLNs were present,without laryngeal non-recurrent nerve(Non-recurrentlaryngealnerve,NRLN)variation,and the dissection process was smooth.The premenstrual skin was cut in the middle,the pretracheal tissue was separated layer by layer,the trachea was exposed,and blunt separation was performed in the tracheoesophageal groove(Tracheoesophagealgroove,TG)to find and determine that RLN,cleared the connective tissue around RLN,dissociated RLN and its branches in the thyroid surgery area,and observed the course of RLN,especially the spatial relationship of RLN entering the larynx in the first and second tracheal ring,so as to avoid traction and injury to RLN in the process of separation.Then,the course of bilateral RLNs in the cervical region and their branches in the thyroid surgery area,the angle between the entry of the RLN into the larynx and the ipsilateral tracheal margin(the line between the most lateral edge of the coronal plane of the tracheal ring)were recorded.The vertical distance between the entry of the RLN into the larynx and the anterior superior edge of the first and second tracheal rings(the most anterior superior edge of the sagittal plane of the tracheal ring)and the horizontal distance between the lateral edge of the ipsilateral first and second tracheal rings(the most lateral edge of the coronal plane of the tracheal ring).Using ruler and triangular ruler to determine the Angle,protractor to measure the Angle,the accuracy is accurate to 0.5°,Using compass to determine the distance,electronic digital display vernier caliper distance measurement,accuracy is 0.01 mm.All the measurements and data statistics are done by the same person,and all the data are statistically analyzed by SPSS17.0 software,and the data are expressed as the average ±standard deviation(?x ±s)minimum-maximum value(Min-Max).Paired sample T test was used to compare the corresponding data of left and right RLN,and the difference was statistically significant(P<0.05).Results:1.Among the bilateral RLN,71 cases of RLN were located in the TG throughout the cervical segment,9 cases of RLN did not walk steadily in the TG,deviated from the TG in the area below the inferior pole of the thyroid,and did not enter the TG until the inferior pole of the thyroid.There were 7 cases on the right side and 2 cases on the left side.2.In the thyroid surgery area,both external laryngeal branches and laryngeal branches could be seen in bilateral RLN,which were divided into 2-5 branches,2branches in 58 cases(72.5%),3 branches in 12 cases(15%),4 branches in 9 cases(11.25%),and 5 branches in 1 case(1.25%).According to the situation of its branches,the morphology of RLN branches can be divided into dendritic and loop-shaped,a total of 73 cases of RLN branches formed dendritic(91.25%),the other 7 cases formed loop-like(8.75%).3.The intersection of the ipsilateral tracheal margin and the entry of the RLN into the larynx was used as the apex of the angle,and the included angles between the entry of the RLN and the ipsilateral tracheal margin of 80 sides were recorded.21 cases with 0°≦ Angle < 5°,accounting for 26.25%;46 cases with5°≦ Angle < 10°,accounting for 57.50%;11 cases with 10°≦ Angle < 15°,accounting for 13.75%;≥15° was found in 2 cases,accounting for 2.50%.The angles between the left and right RLNs entering the larynx and the ipsilateral tracheal margin were 6.0±0.5(0-21)° and 7.0±0.5(0-25)°,respectively.4.The vertical distances between the left and right RLNs and the anterior superior edge of the first tracheal ring were(19.72±0.52)mm and(21.21±0.43)mm,respectively.The vertical distances from the front and upper edge of the second tracheal ring were(20.91±0.49)mm and(21.42±0.39)mm,respectively.Horizontal distances from the lateral edge of the ipsilateral first tracheal ring were(2.96±0.11)mm and(2.96±0.10)mm,respectively.Horizontal distances from the lateral edge of the ipsilateral second tracheal ring were(3.49±0.12)mm and(3.50±0.52)mm,respectively.Conclusion: The entry angle of bilateral RLNs into the larynx and the position of recurrent laryngeal nerve in the first and second tracheal ring are relatively fixed.Understanding the more anatomy of the RLN and its more delicate entry into the larynx can help find the RLNs more efficiently and safely intraoperatively,help identify and expose the RLNs,reduce the damage to the RLNs during thyroid surgery,and thus lower the incidence of complications in thyroid surgery. |
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