QS Study

The larynx is the organ for phonation. It is an organ located in the anterior neck. It is located within the anterior aspect of the neck, anterior to the inferior portion of the pharynx and superior to the trachea. It goes from the root of the tongue to the trachea and is located in front of the 3rd, 4th, 5th, and 6th cervical vertebrae. It is a component of the respiratory tract.

The recurrent laryngeal nerve supplies all the intrinsic muscles of the larynx except cricothyroid.

When both recurrent laryngeal nerves are interrupted, the vocal cords lie in the cadaveric position (in between abduction and adduction) and phonation is completely lost (aphonia). Breathing also becomes difficult through the partially opened glottis. When one recurrent laryngeal nerve is paralyzed, the opposite vocal cord compensates for it and phonation is possible but difficult (dysphonia).

In progressive lesions of the recurrent laryngeal nerve, the abductors of the vocal cords are first to be paralyzed and last to recover. The recurrent laryngeal nerve in its course from the brain stem to the larynx follows a path that brings it in proximity to numerous structures. These structures can interfere with its function by pressure or by disruption of the nerve caused by disease invading the nerve.

laryngeal nerve is paralyzed 1

Fig: When the nerve is injured, muscles are unable to move and then vocal cord does not move

On the other hand, in functional paralysis of laryngeal muscles, the adductors are the first to be paralyzed.

In bilateral partial section of the recurrent laryngeal nerve, bilateral paralysis of the abductor muscles and the drawing together of the vocal cords.

Acute breathlessness and stridor follow and cricothyroidotomy or tracheostomy is necessary.

Related Study: