Anatomic relation between the external branch of the superior laryngeal nerve and the thyroid gland

Abstract

Aim: This prospective study investigated the anatomic relations between the external branch of the superior laryngeal nerve (eBSLn), the superior thyroid artery (STA) and the thyroid gland in human cadavers. Material and Methods:Twenty-two human cadavers aged over 18 years old, less than 24 hours after death. Results:The mean distance between the eBSLn and the superior pole of the thyroid gland was 7.68 ±3.07 mm. A tangent to the inferior edge of the thyroid cartilage between the eBSLn and the STA measured 4.24 ±2.67 mm. A line from the intersection of the eBSLn -related to the STA -to the superior pole of the thyroid gland measured 9.53 ±4.65 mm. A line from the eBSLn to the midline of the most caudal point of the thyroid cartilage measured 19.70 ±2.82 mm. A line from the renLS to the midline on the most cranial point of the cricoid cartilage was 18.35 ±3.66 mm. Conclusion:There is a variable proximity relation between the eBSLn and the superior pole of the thyroid gland; this distance ranges from 3.25 to 15.75 mm. There was no evidence of significant variation between the measures in the ethnic groups comprising the sample. Braz J Otorhinolaryngol. 2011;77(2):249-58. ORIgInAL ARTIcLE BJORL

A Closer Look at Laryngeal Nerves during Thyroid Surgery: A Descriptive Study of 584 Nerves

“…It has to be noted that as the gland size increases the incidence of type 2 nerves increases and thereby the chances of injury become high [7]. Estrela et al [17] demonstrated in cadaveric study that the EBSLN was closer to the cranial point of thyroid lobe and crossed the STA very close to the cranial most part of the thyroid lobe in younger individuals (18–39 years age group). These findings suggest that younger individuals are at higher risk of nerve injury due to the type 2 nature of the EBSLN.…”

Anatomía Topográfica del Nervio Laríngeo Superior: Importancia Quirúrgica en las Tiroidectomías

“…El ramo inferior o lateral del nervio laríngeo superior (RLNLS), de menor calibre con respecto al ramo inerno, nace a la altura del hueso hiodes, se dirige oblicuamente hacia abajo, posterior al músculo esternotiroideo, relacionándose a este nivel con a la Arteria tiroidea superior (ATS), que corre en un pano más profundo al mismo. Desciende a lo largo de la inserción anterior en del músculo constrictor inferior de la faringe, entre el músculo y la glándula tiroides, recorriendo su cara superficial y perforándolo a una altura variable e inervándolo , rodea al asta inferior del cartílago tiroideo para llegar al músculo cricotiroideo al que también inerva, para terminar en la mucosa subglótica tras perforar la membrana cricotirodea (Estrela et al, 2011).…”

“…El RLNLS es principalmente motor, pero termina como ramo sensitivo de la mucosa subglótica a nivel de la membrana cricotiroidea, recibiendo además anastomosis del simpático cervical, específicamente provenientes del ganglio cervical superior, asi como anastomosis motoras provenientes del NLI, que colaborarían en la inervación motora de otros múscculos intrínsecos de la laringe (Sanders et al, 1993;Wu et al, 1994;Maranillo et al, 2003;Estrela et al;Gurleyik, 2018).…”

“…La acción principal del RLNLS es la inervación motora del músculo cricotiroideo, el cual tensa las cuerdas vocales produciendo sonidos de alta frecuencia, mayores a 150 Hz, manteniendo a su vez en tensión a las mismas durante la fonación, permitiendo así una fonación de tonos altos. Además optimiza la respiración evitando la broncoaspiración durante la deglución (Estrela et al;Dessie, 2018).…”

Observations on the Superior Thyroid Artery and its Relationship with the External Laryngeal Nerve

“…The ELN gives branches to the pharyngeal plexus and the superior part of inferior constrictor: it also communicates with the superior cardiac nerve and the superior cervical sympathetic ganglion deep to the common carotid artery [11]. The external laryngeal nerve (ELN) descends on superficial aspect of the larynx deep to sternothyroid giving fibers to cricothyroid [12], which maintains the vocal cords under tension during phonation [13]. In contrast the internal laryngeal nerve descends towards and pierces the thyrohyoid membrane.…”