The Anatomical and Clinical Significance of the Superior Laryngeal Nerve

2021 ◽  
pp. 019459982198962
Author(s):  
Kai-ning Lu ◽  
Jin-wang Ding ◽  
Yu Zhang ◽  
Jing-jing Shi ◽  
Li Zhou ◽  
...  
Keyword(s):  
Thyroid Cartilage ◽  
Superior Laryngeal Nerve ◽  
Laryngeal Nerve ◽  
Entry Point ◽  
Horizontal Line ◽  
Lower Edge ◽  
External Branch ◽  
Starting Point ◽  
Human Cadavers ◽  
Medical University

Objective This study summarizes the anatomical features of the superior laryngeal nerve in Chinese to enable the rapid location of the superior laryngeal nerve during an operation. Study Design Retrospective analysis of anatomical data. Setting Hangzhou First People’s Hospital Affiliated to Nanjing Medical University. Methods A total of 71 embalmed human cadavers (132 heminecks) were examined over 3 months. The length and diameter of the internal and external branches of the superior laryngeal nerve and their relationships with different landmarks were recorded. Results The total length of the internal branch of the superior laryngeal nerve was 23.4 ± 6.9 mm. The length of the external branch of the superior laryngeal nerve was 47.7 ± 11.0 mm. Considering the midpoint of the lower edge of the thyroid cartilage as the starting point and using that edge as a horizontal line, when the entry point is above that line, the external branch of the superior laryngeal nerve can be found within 41.1 mm and at an angle of 57.2°. When the entry point is below the lower edge of the thyroid cartilage, the external branch of the superior laryngeal nerve can be found within 34.0 mm and at an angle of 36.5°. Conclusion The superior laryngeal nerve in Chinese people has distinct anatomical characteristics. This article provides a new method of quickly locating the external branch of the superior laryngeal nerve during the operation, which can reduce the probability of damaging the external branch of the superior laryngeal nerve.

scholarly journals Anatomical landmarks of the external branch of the superior laryngeal nerve

2019 ◽  
Vol 12 (4) ◽  
pp. 161-177
Author(s):  
Viktor Y. Malyuga ◽  
Aleksandr A. Kuprin
Keyword(s):  
Thyroid Cartilage ◽  
Oblique Line ◽  
Superior Laryngeal Nerve ◽  
Laryngeal Nerve ◽  
Constrictor Muscle ◽  
External Branch ◽  
Close Proximity ◽  
Inferior Pharyngeal Constrictor ◽  
Line Type

Background. The external branch of the superior laryngeal nerve innervates a cricothyroid muscle, which provides tension in vocal cords and formation of high-frequency sounds. When the nerve is damaged during surgery, patients may notice hoarseness, inability to utter high pitched sounds, “rapid fatigue” of the voice, and dysphagia. According to literature, paresis of an external branch of the superior laryngeal nerve reaches up to 58% after thyroid surgery. Aim: to identify permanent landmarks and topographic variations of the external branch of the superior laryngeal nerve. Materials and methods. The study is based on the autopsy material (21 complexes organs of the neck) and on identification of variations of 40 external branches of the superior laryngeal nerve. We identified two permanent landmarks that are located at the minimum distance from nerve and we made metrical calculations relative to them: oblique line of thyroid cartilage and tendinous arch of the inferior pharyngeal constrictor muscle. Results. The piercing point of the nerve is always located at the inferior pharyngeal constrictor muscle without protruding beyond the oblique line of thyroid cartilage superiorly and tendinous arch of the inferior pharyngeal constrictor muscle anteriorly. The nerve had the parallel direction in 92.8% of cases (angel less than 30 degrees) relative to the oblique line and in 85.7% cases it was in close proximity to this line (at distance up to 4 mm). The proposed topographic classification of the location of the external branch of the superior laryngeal nerve is based on localization of the piercing point of the nerve relative to the length of the oblique line of thyroid cartilage and the risk of nerve damage. In 14.2% of cases, the piercing point was in the front third of the line (type I), and in 50% it was in the middle third of this line (type II). These variations of the external branch of the superior laryngeal nerve was in close proximity to the upper pole of the thyroid gland, which could have lead to its damage during surgery. In type III and IV (35.8%) – the piercing point in the muscle was located as far as possible from the upper pole of the thyroid gland and the greater part of the nerve was covered with the fibers of inferior pharyngeal constrictor muscle. Conclusion. We identified the main orienteers for the search and proposed anatomical classification of the location of the external branch on the superior laryngeal nerve.

scholarly journals Protection of the external branch of the superior laryngeal nerve in Transoral endoscopic thyroidectomy vestibular approach (TOETVA): an observational study

2021 ◽  
Author(s):  
Zhen Wu ◽  
Jugao Fang ◽  
Hongzhi Ma ◽  
Xiao Chen ◽  
Qi Zhong ◽  
...  
Keyword(s):  
Contractile Activity ◽  
Endoscopic Thyroidectomy ◽  
Thyroid Cartilage ◽  
Superior Laryngeal Nerve ◽  
Laryngeal Nerve ◽  
External Branch ◽  
Protective Strategies ◽  
The Right ◽  
Intraoperative Nerve Monitoring ◽  
Vestibular Approach

Abstract Background: Avoiding injury of the external branch of the superior laryngeal nerve（EBSLN） is one of the major challenges during thyroid surgery, especially in transoral endoscopic thyroidectomy vestibular approach (TOETVA). This study aimed to investigate the protective strategies of the EBSLN during TOETVA. Methods: In order to protect the EBSLN during TOETVA, we adopted the method of identification the nerve by anatomy and localization. The method of anatomy involves the dissection of EBSLN by complete transection of the sternothyroid muscle in the attachment of the thyroid cartilage. The method of localization involves nerve stimulation localization, which produces cricothyroid contractile activity through intraoperative nerve monitoring stimulation (IONM). Concurrently, patients were evaluated preoperatively and at 1 and 3 weeks postoperatively in an individual prospective cohort study using a stroboscopic laryngoscope and the voice handicap index-10 (VHI-10). The VHI-10 score was used to evaluate voice changes. Results: We retrospectively analyzed patients with papillary thyroid cancer (PTC) who underwent TOETVA in the thyroid center of the Beijing Tongren hospital between February 2018 and June 2020. Patients with recurrent laryngeal nerve（RLN）damage were excluded. Sixty patients were enrolled in this study, of which four underwent total thyroidectomy. Intraoperatively, 56 EBSLNs were located (56/64, 87.50%). Among these, the left EBSLN was identified in 20/25(80.00%) and the right EBSLN was identified in 36/39 (92.31%) cases. One week postoperatively, a blinded stroboscopic laryngoscope examination showed that no patient had paresis of the EBSLN. However, the VHI-10 score was significantly higher than the preoperative value (10.58 ± 4.54 vs. 3.00 ± 1.54, p＜0.01). At three weeks postoperatively, the overall score was still different from that preoperatively (4.83 ± 3.34 vs. 3.00 ± 1.54, p＜0.01); however, the vast majority of patients returned to their preoperative status. Conclusion: In TOETVA, the EBSLN can be well exposed by transection of the sternothyroid muscle, and combined with IONM, the protection of the function of the EBSLN can be guaranteed. Simultaneously, we observed that TOETVA could cause a short-term voice handicap in patients, with such changes generally returning to normal within three weeks.

scholarly journals VIRIATION OF THE EXTERNAL BRANCH OF THE SUPERIOR LARYNGEAL NERVE

2019 ◽  
Vol 21 (1) ◽  
pp. 84-88
Author(s):  
V Y Malyuga ◽  
A A Kuprin
Keyword(s):  
Thyroid Gland ◽  
Thyroid Cartilage ◽  
Oblique Line ◽  
Superior Laryngeal Nerve ◽  
Laryngeal Nerve ◽  
Type I ◽  
Constrictor Muscle ◽  
Point Of Entry ◽  
External Branch ◽  
Inferior Pharyngeal Constrictor

Till now, there is no universal clinical classification about variations of the external branch of the superior laryngeal nerve despite the multiple classifications that was proposed. The aim of this research is identification and systematization of topographic types of the external branch of the superior laryngeal nerve. The study is based on the autopsy material (21 complexes organs of the neck) and on identification of variations of 40 external branches of the superior laryngeal nerve. We identify two permanent landmark that are located at the minimum distance from nerve and on which we made metrical calculations: oblique line of thyroid cartilage, tendinous arch of the inferior pharyngeal constrictor muscle. The “entry” point of the nerve is always located on the inferior pharyngeal constrictor muscle,and not protruding beyond the oblique line of thyroid cartilage superiorly and tendinous arch of the inferior pharyngeal constrictor muscle anteriorly. The proposed topographic classification of the location of the external branch of the superior laryngeal nerve is based on localization of point of pierced of the nerve relating to the length of the oblique line of thyroid cartilage. In 64.2% of cases, the external branch of the superior laryngeal nerve was in close proximity to the upper pole of the thyroid gland, which could lead to its damage during surgery (type I and II). In type III and IV (35.8%) - the point of "entry" in the muscle was located as far as possible from the upper pole of the thyroid gland, and most of the nerve was covered by the fibers of the inferior pharyngeal constrictor muscle.

Electrophysiologic identification and monitoring of the external branch of superior laryngeal nerve during thyroidectomy

2014 ◽  
Vol 219 (4) ◽  
pp. e85-e86
Author(s):  
Salah Eldin Mohamed ◽  
Mohammed H. Alshehri ◽  
Rizwan Aslam ◽  
Zaid Al-Qurayshi ◽  
Emad Kandil
Keyword(s):  
Superior Laryngeal Nerve ◽  
Laryngeal Nerve ◽  
External Branch

scholarly journals Assessment of Relation between External Branch of Superior Laryngeal Nerve & Thyroid Gland- A Cadaveric Study

2020 ◽  
Vol 6 (2) ◽  
pp. 73-76
Author(s):  
Anurag ◽  
Vishnu Gupta
Keyword(s):  
Thyroid Gland ◽  
Cricoid Cartilage ◽  
Superior Laryngeal Nerve ◽  
Laryngeal Nerve ◽  
The Body ◽  
Superior Thyroid Artery ◽  
Group I ◽  
External Branch ◽  
The Mean ◽  
Group Ii

Background: The thyroid gland is essential for normal growth of the body. This study assessed relation of external branch of superior laryngeal nerve to the superior pole of the thyroid gland. Subjects and Methods: This study was conducted on 25 human cadavers having 50 superior thyroid poles of both genders. Cadavers were classified based on age groups, group I was those with age less than 39 years and group II cadavers were those with age more than 40 years of age. Various measurements were performed on cadavers. Results: 14 cadavers were I group I and 11 were in group II. The mean mass was 67.2 Kgs in group I and 59.5 Kgs in group II, time elapsed after death was 481.5 minutes in group I and 476.4 minutes in group II, mean height was 1.74 meters in group I and 1.69 meters in group II, mean BMI found to be 22.3 kg/m2in group I and 20.1 kg/m2in group II. Height found to be significant between both groups (P< 0.05). The mean distance from EBSLN to cranial point of the thyroid gland was 6.66 mm in group I and 8.96 mm in group II. The mean transverse distance from superior thyroid artery to EBSLN was 3.55 mm in group I and 5.12 mm side in group II. The mean distance of the crossing point between the most cranial point of the thyroid lobe was 6.40 mm in group I and 11.47 mm in group II. The mean distance from the EBSLN to the midline of the neck was 19.80 mm in group I and 18.58 mm in group II. The mean distance from the EBSLN to the midline of the neck on the most cranial point of the cricoid cartilage was 18.77 mm in group I and 17.80 mm in group II. Conclusion: Authors found variation in measurements in left and right side in both group I and group II.

scholarly journals Retrograde Thyroidectomy for preservation of the External Branch of the Superior Laryngeal Nerve: A case series

2018 ◽  
Vol 53 ◽  
pp. 517-521
Author(s):  
Vijay Naraynsingh ◽  
Shamir Cawich ◽  
Dale Hassranah ◽  
Ravi Maharaj ◽  
Shariful Islam ◽  
...  
Keyword(s):  
Case Series ◽  
Superior Laryngeal Nerve ◽  
Laryngeal Nerve ◽  
External Branch
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