Recurrent laryngeal nerve

Nerve: Recurrent laryngeal nerve
POSTERIOR VIEW: The tracheobronchial lymph glands (I. and E. Recurrent nerves visible at top.)
Course and distribution of the glossopharyngeal, vagus, and accessory nerves.
Latin	nervus laryngeus recurrens
Gray's	subject #205 912
Innervates	larynx posterior cricoarytenoid lateral cricoarytenoid arytenoid thyroarytenoid
From	vagus nerve

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 the nerve of the 6^th Branchial Arch.

Path

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 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.

Clinical significance

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.

History

Galen is said to have first described the clinical syndrome of recurrent laryngeal nerve paralysis.

Veterinary medicine

In Veterinary medicine, 'roars' refers to a deficit in the left recurrent laryngeal nerve causing characteristic stertorous sounds upon inspiration.

It is treatable by specialists in equine medicine.

Additional images

The right sympathetic chain and its connections with the thoracic, abdominal, and pelvic plexuses.

The position and relation of the esophagus in the cervical region and in the posterior mediastinum. Seen from behind.

Recurrent laryngeal nerve

External links

• 369492028 at GPnotebook
• SUNY Figs 21:04-01
• cranialnerves at The Anatomy Lesson by Wesley Norman (Georgetown University) (X)
• Example of Vocal Cord Paralysis