Skip to main content Accessibility help

Anatomical variations of the external branch of the superior laryngeal nerve in relation to the inferior constrictor muscle: cadaveric dissection study

  • U Patnaik (a1), A Nilakantan (a1) and T Shrivastava (a2)



To determine anatomical variations in the external branch of the superior laryngeal nerve in relation to the inferior constrictor muscle, and to propose a rational approach for the preservation of the nerve in thyroid surgery based on anatomical principles.


A cadaveric dissection study of the anatomy of the external branch of the superior laryngeal nerve in relation to the inferior constrictor muscle was conducted. Twenty-nine formalin-fixed cadavers of both sexes (age 50–70 years), with normal necks, were examined.


In relation to the Friedman classification, three anatomical variations of the external branch of the superior laryngeal nerve were found. Type 1 variation was found in 57.1 per cent of cases, type 2 in 26.8 per cent and type 3 in 16 per cent.


The prevalence of type 3 variation of the external branch of the superior laryngeal nerve suggests that the nerve will not be encountered in a certain percentage of individuals as it lies under the cover of the inferior constrictor. Therefore, there is no justification for attempting to identify the nerve in all cases.


Corresponding author

Address for correspondence: Dr U Patnaik, Department of ENT, Base Hospital and Army College of Medical Sciences, Delhi Cantonment, New Delhi 110010, India Fax: +91 (0)112 333 7002 E-mail:


Hide All
1Roy, AD, Gardiner, RH, Niblock, WM. Thyroidectomy and the recurrent laryngeal nerves. Lancet 1956;270:988–90
2Borley, NR, Healey, JC, Collins, P, Johnson, D, Crossman, AR, Mahadevan, V et al. Neck. In: Standring, S, ed. Gray's Anatomy, 40th edn.London: Elsevier, 2008;435–66
3Perry, A. Speech therapy in ENT practice: scope, science and evidence for intervention. In: Gleeson, M, ed. Scott-Brown's Otolaryngology, Head and Neck Surgery, 7th edn.Great Britain: Hodder Arnold, 2008;2216–33
4Jansson, S, Tisell, L, Hagne, I, Sanner, E, Stenborg, R, Svensson, P. Partial SLN lesions before and after thyroid surgery. World J Surg 1988;12:522–7
5Friedman, M, Lo Savio, P, Ibrahim, H. Superior laryngeal nerve identification and preservation in thyroidectomy. Arch Otolaryngol Head Neck Surg 2002;128:296303
6Cernea, CR, Nishio, S, Hojaji, FC. Identification of the EBSLN in large goiters. Am J Otolaryngol 1995;16:307–11
7Kierner, AC, Aigner, M, Burian, M. The external branch of the superior laryngeal nerve: its topographical anatomy as related to surgery of the neck. Arch Otolaryngol Head Neck Surg 1998;124:301–3
8Lore, JM, Kokocharov, SI, Kaufman, S, Richmond, A, Sundquist, N. 38-year evaluation of a surgical technique to protect the EBSLN during thyroidectomy. Ann Otol Rhinol Laryngol 1998;107:1015–22
9Kark, AE, Kissin, MW, Auerbach, R, Meikle, M. Voice changes after thyroidectomy: role of the external laryngeal nerve. BMJ 1984;289:1412–15
10Cernea, C, Ferraz, AR, Furlani, J, Nishio, S, Hojaij, FC, Dutra, A et al. Identification of the external branch of the superior laryngeal nerve during thyroidectomy. Am J Surg 1992;164:634–9
11Choksy, SA, Nicholson, ML. Prevention of voice changes in singers by using a nerve stimulator to identify the external laryngeal nerve. Br J Surg 1996;83:1131–2
12Lore, JM, Kim, DJ, Elias, S. Preservation of the laryngeal nerves during total thyroid lobectomy. Ann Otol Rhinol Laryngol 1977;86:777–88
13Jonas, J, Bahr, R. Neuromonitoring of the EBSLN during thyroid surgery. Am J Surg 2000;179:234–6
14Teitelbaum, BJ, Wenig, BL. Superior laryngeal nerve injury from thyroid surgery. Head Neck 1995;17:3640
15Lekacos, NL, Miligos, ND, Tzaedis, PJ, Majiatis, S, Patoulis, J. The SLN in thyroidectomy. Am Surg 1987;53:610–12
16Moran, RE, Castro, AF. The superior laryngeal nerve in thyroid surgery. Ann Surg 1951;134:1018–21
17Arnold, GE. Vocal rehabilitation of paralytic dysphonia. Arch Otolaryngol Head Neck Surg 1962;76:358–68
18Hong, KH, Kim, YK. Phonatory characteristics of patients undergoing thyroidectomy without laryngeal nerve injury. Otolaryngol Head Neck Surg 1997;117:399404
19Lennquist, S, Cahlin, C, Smeds, S. The superior laryngeal nerve in thyroid surgery. Surgery 1987;107:1015–22
20Shah, JP, Patel, SG. Thyroid and parathyroid glands. In: Shah, JP, ed. Head and Neck Surgery and Oncology, 3rd edn.London: Elsevier, 2005;395437



Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed