The recurrent (inferior) laryngeal nerve
is a branch of the vagus nerve (tenth cranial nerve
) that supplies motor function and sensation to the larynx
(voice box). It travels within the endoneurial sheath.
It is referred to as "recurrent" because the branches of the nerve innervate the laryngeal muscles
in the neck through a rather circuitous route: they descend into the thorax
before rising up between the trachea and esophagus to reach the neck.
The left laryngeal nerve branches from the Vagus [X] nerve to loop under and around the arch of the aorta (ligamentum arteriosum) before ascending, whereas the right branch loops around the right subclavian artery. The right laryngeal nerve branches from the Vagus [X] nerve and loops under the right subclavian artery.
The nerve splits into anterior and posterior rami before supplying muscles in the voice box — it supplies all laryngeal muscles except for the cricothyroid, which is innervated by the external branch of the superior laryngeal nerve.
The recurrent laryngeal nerve enters the pharynx, along with the inferior laryngeal artery, below the inferior constrictor muscle.
The nerve is best known for its importance in thyroid
surgery, as it runs immediately posterior to this gland. If it is damaged during surgery, the patient will have a hoarse voice. Nerve damage can be assessed by laryngoscopy
, during which a stroboscopic
light confirms the absence of movement in the affected side of the vocal cords.
Similar problems may also be due to invasion of the nerve by a tumor or after trauma to the neck. A common scenario is paralysis of the left vocal cord due to malignant tumour in the mediastinum affecting the left branch of the recurrent laryngeal nerve. The left cord returns to midline where it stays.
- If the damage is unilateral, the patient may present with voice changes including hoarseness.
- Bilateral nerve damage can result in breathing difficulties and aphonia, the inability to speak.
- The right recurrent laryngeal nerve is more susceptible to damage during thyroid surgery due to its relatively medial location.
is said to have first described the clinical syndrome of recurrent laryngeal nerve paralysis.
medicine, 'roars' refers to a deficit in the left recurrent laryngeal nerve causing characteristic stenuous sounds upon inspiration.
It is treatable by specialists in equine medicine.