Superior laryngeal nerve
Division or branch · detail · CN X Mixed
Leaves the vagus just below the jugular foramen at the inferior (nodose) ganglion and divides into an internal branch that pierces the thyrohyoid membrane to supply sensation above the vocal folds and an external branch that runs with the superior thyroid artery to the cricothyroid muscle.
Traced from the start
Detail
- Motor
- Cricothyroid (external branch): tenses and lengthens the vocal folds to raise pitch
- Sensory
- Laryngeal mucosa above the vocal folds, epiglottis and vallecula (internal branch); afferent limb of the laryngeal cough reflex and taste from the epiglottis
- Surgical relation
- The external branch crosses the superior thyroid artery close to the upper pole of the thyroid, so the artery is ligated as near the gland as possible
When it goes wrong
External branch injured while ligating the superior thyroid artery at thyroidectomy
Loss of the upper vocal range, easy voice fatigue and inability to project, with cords that look normal at laryngoscopy; disabling for singers and teachers
Internal branch anaesthetised for awake bronchoscopy or intubation, or damaged at surgery
Loss of supraglottic sensation and the protective cough with aspiration risk; keep the patient nil by mouth until sensation returns
Practise this structure
1 question in the bank tagged Vagus Nerve.