The recurrent laryngeal nerve is a branch of the vagus nerve, which is an important nerve in the nervous system. The vagus nerve is the tenth cranial nerve, which originates in the brain stem and gets divided into many branches. This nerve is responsible for supplying motor function to the main area which generates our voice―the larynx.
Path of the Recurrent Laryngeal Nerve
The name of any nerve is defined by its path. This nerve is called 'recurrent' because of the route that it takes in the head, neck, and thoracic region. It innervates the main laryngeal muscles. It descends from the thorax, then returns from the region between the wind pipe and food pipe, hence, re-entering the neck. It is further divided into the left and right recurrent laryngeal nerves. The left branch breaks off from the vagus and finds its way around the main arch of the aorta. The right branch goes around the right subclavian artery. Basically, it is responsible for the innervation of very important intrinsic muscles of the larynx, except for the cricothyroid muscle. It is also responsible for producing sound, as it brings about both, adduction and abduction of the vocal folds.
Recurrent Laryngeal Nerve Block
Recurrent laryngeal nerve block procedure is used to anesthetize it, and it is done by placing the patient in a supine position. Firstly, local anesthetic solution is drawn into a sterile syringe. Next, the sternocleidomastoid muscle's medial border is identified, and the needle is inserted in such a manner that it lies perpendicular to the skin. After this, aspiration should be done in order to ensure that no blood comes out. After aspiration is clear, the solution is injected slowly.
There are quite a few risks involved in this procedure, due to the proximity of this nerve to many important structures, like the carotid artery, jugular vein, and numerous vital structures in the neck region. The chances of complications like hematoma arising are quite high due to the presence of many blood vessels in this region. Therefore, one should always keep anticoagulants at hand while doing this procedure. If a hematoma does take place, then an ice pack helps decrease the blood flow. One should always apply manual pressure at the site of injection, in order to decrease the chances of such complications.
As mentioned earlier, because this vital nerve supplies information to the intrinsic muscles of the larynx, besides the cricothyroid, a bilateral nerve block is only meant for those patients who have undergone a laryngectomy, or a tracheostomy. Bilateral block to the nerve may lead to the paralysis of the vocal cords, eventually resulting in obstruction of the airways.
Finally, this is an important nerve and its pathological significance is huge. Paralysis of the larynx resulting from damage to this nerve is a serious condition. It may occur due to a tumor in the chest region, or if there is an aneurysm in the aorta, which compresses the left branch of the nerve. According to some claims, the recurrent laryngeal nerve evolution is to blame for its topsy-turvy path. However, scientists dismiss such claims as wishful thinking.