[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anatomy](https://durgical.com/en/anatomy/) › [Head and neck](https://durgical.com/en/anatomy/region/head-and-neck/) › Superior laryngeal nerve [Nervous system](https://durgical.com/en/anatomy/system/nervous-system/) · [Head and neck](https://durgical.com/en/anatomy/region/head-and-neck/) # Superior laryngeal nerve The superior laryngeal nerve, a branch of the vagus, gives feeling inside the upper voice box and tightens the vocal cords for high notes. [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=head_neck&select=superior_laryngeal_nerve&side=r) Opens in the Durgical app, no sign-up needed. ## What it is A vagus branch high in the neck with an internal and an external branch. ## What it does Feeling inside the upper larynx and the cricothyroid muscle (high notes). ## Key points - Internal branch: pierces the thyrohyoid membrane with the superior laryngeal artery and carries sensation from the larynx above the [vocal folds](https://durgical.com/en/anatomy/vocal-fold/), the [epiglottis](https://durgical.com/en/anatomy/epiglottis/) and the piriform fossa - Loss of the internal branch removes the cough and protective closure reflexes above the glottis, so food and saliva can be aspirated silently - External branch: runs down on the inferior constrictor beside the [superior thyroid artery](https://durgical.com/en/anatomy/superior-thyroid-artery/) to the cricothyroid, the muscle that tenses the vocal folds for high pitch; at risk in thyroid surgery ## Key facts **Roots** Vagus (inferior ganglion); internal and external branches **Moves** Cricothyroid (external branch) **Feeling from** Larynx above the vocal folds (internal branch: cough reflex) ## Relations **Course** Leaves the inferior (nodose) ganglion of the [vagus nerve](https://durgical.com/en/anatomy/vagus-nerve/), runs down and forward on the side of the [pharynx](https://durgical.com/en/anatomy/pharynx/) deep to the [internal carotid artery](https://durgical.com/en/anatomy/internal-carotid-artery/), and divides near the greater horn of the [hyoid bone](https://durgical.com/en/anatomy/hyoid-bone/) into its two branches **Lateral** Internal and external [carotid arteries](https://durgical.com/en/anatomy/common-carotid-artery/), which lie superficial to it **Medial** Middle and inferior [pharyngeal constrictors](https://durgical.com/en/anatomy/superior-pharyngeal-constrictor/) **Below** The internal branch enters the larynx through the [thyrohyoid membrane](https://durgical.com/en/anatomy/median-thyrohyoid-ligament/) and runs under the mucosa of the piriform fossa; the external branch reaches the [cricothyroid](https://durgical.com/en/anatomy/oblique-part-of-cricothyroid-muscle/) near the upper pole of the [thyroid gland](https://durgical.com/en/anatomy/thyroid-gland/) ## How to find it The internal branch is targeted in a superior laryngeal nerve block just below the greater horn of the hyoid bone, where it pierces the thyrohyoid membrane; it can also be numbed from inside through the mucosa of the piriform fossa. In thyroid surgery the external branch is looked for on the inferior constrictor, medial to the upper pole vessels. ## Examination - Laryngeal adductor reflex on flexible endoscopy: a light touch or air pulse on the aryepiglottic fold normally closes the vocal folds briefly; a weak or absent response points to loss of internal branch sensation ## On imaging Not usually seen as a nerve. For a block, ultrasound finds its internal branch region beside the greater horn of the hyoid, over the thyrohyoid membrane, with the superior laryngeal artery on Doppler as a guide. After an injury the main test is laryngoscopy, not imaging; CT or MRI of the neck from the skull base to the larynx looks for a mass along its path. ## Clinical notes - Cernea types describe where the external branch crosses the superior thyroid vessels; the type that crosses below the upper edge of the gland (2b) is the most exposed - Bilateral superior laryngeal nerve blocks, with topical or transtracheal anaesthesia, numb the airway for awake fibreoptic intubation - A high vagal lesion injures the superior and [recurrent laryngeal nerves](https://durgical.com/en/anatomy/recurrent-laryngeal-nerve/) together: hoarse voice plus a numb larynx, with a greater risk of aspiration than a recurrent nerve lesion alone - Superior laryngeal neuralgia: brief stabbing pain in the side of the throat on swallowing, yawning or coughing, with a tender point over the thyrohyoid membrane ## Anatomical variants - The internal branch often joins the recurrent laryngeal nerve inside the larynx (Galen anastomosis) - The external branch sometimes runs within the fibres of the inferior constrictor, which shields it during surgery - Its relation to the superior thyroid artery varies widely, which is why surgeons identify it rather than assume its position ## Development It is the nerve of the fourth pharyngeal arch, which is why its external branch supplies the cricothyroid, the only intrinsic laryngeal muscle outside the recurrent laryngeal nerve's territory. ## Memory aid External to the External muscle: the cricothyroid is the only intrinsic laryngeal muscle on the outside of the larynx; Internal goes Inside, for sensation. ## Related conditions - [Thyroid cancer (papillary)](https://durgical.com/en/conditions/thyroid-cancer/) ## Test yourself Think of the answer, then tap the question to see it. ## What does the internal branch of the superior laryngeal nerve supply, and how does it enter the larynx? Sensation of the larynx above the vocal folds, epiglottis and piriform fossa; it pierces the thyrohyoid membrane with the superior laryngeal artery. ## Which muscle does the external branch of the superior laryngeal nerve supply, and why is it at risk in thyroid surgery? The cricothyroid, which tenses the vocal folds for high pitch; it runs beside the superior thyroid artery near the upper pole. ## Why does loss of the internal branch of the superior laryngeal nerve risk aspiration? It removes the cough and protective closure reflexes above the glottis, so food and saliva can be aspirated silently. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/anatomy/superior-laryngeal-nerve/) Educational information, not medical advice. For any symptom, see a health professional. ## Its names **Official Latin (TA2)** nervus laryngeus superior TA2 6339 **Official Spanish (DeCS)** Nervio laríngeo superior DeCS D007823 **English (TA2)** Superior laryngeal nerve **Also called** nervus laryngicus cranialis ## Related - [Cricothyroid](https://durgical.com/en/anatomy/oblique-part-of-cricothyroid-muscle/) Sources: Terminologia Anatomica (TA2); [DeCS](https://decs.bvsalud.org/es/ths/resource/?id=8002); [Anatomy, Head and Neck: Laryngeal Nerves](https://www.ncbi.nlm.nih.gov/books/NBK557742/); [Anatomy, Head and Neck: Larynx](https://www.ncbi.nlm.nih.gov/books/NBK538202/). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/anatomy/superior-laryngeal-nerve/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). 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