Anatomy

The framework of the larynx is built of three single cartilages and three paired cartilages. The unpaired cartilages are: the cricoid cartilage, a thick cartilage ring on top of the trachea; the thyroid cartilage, a V-shaped cartilage that sits on the cricoid with the point of its 'V' facing forward; and above this, the epiglottic cartilage, shaped like an upright paddle, with its handle held inside the front angle of the thyroid cartilage. The three smaller paired cartilages are: the arytenoids, the corniculates, and the cuneiforms. These nine cartilages are held together by membranes and ligaments, usually named by the structures that are interconnected; for example, the cricothyroid membrane connects the front of the cricoid cartilage with the base of the thyroid cartilage in the midline.

The intrinsic muscles of the larynx -- cricothyroid, posterior cricoarytenoid, lateral cricoarytenoid, thyroarytenoid, transverse and oblique arytenoids, and vocalis -- alter the length and tension of the vocal cords and the size and shape of the opening between them (the rima glottis). The vagus nerve supplies motor and sensory innervation to the larynx; the cricothyroid muscle is innervated by the external laryngeal branch of the vagus, while the other intrinsic muscles are innervated by the recurrent laryngeal branch of the vagus.

The cavity within the larynx comprises three consecutive chambers. The first chamber, the vestibule of the larynx, is a tube between the pharynx and a pair of folds, the vestibular folds (the "false vocal cords"), that protrude into the larynx. The second chamber, the ventricle of the larynx, is a short segment between the vestibular folds and the vocal folds; the ventricle has lateral recesses extending laterally under the vestibular folds. The third chamber, the infraglottic cavity (infraglottic larynx, subglottic space), is a tube between the vocal folds and the trachea.

Symptoms

Symptoms may include coughing, choking, dyspnea, fixed pain, or loss of voice.

Patient care

If the patient is able to speak or cough, the rescuer should not interfere with the patient's attempts to expel the object. If the patient is unable to speak, cough, or breathe, the rescuer should apply the Heimlich maneuver 6 to 10 times rapidly in succession. Using air already in the lungs, the thrusts create an artificial cough to propel the obstructing object out of the airway. If the patient loses consciousness, carefully assist him or her to the ground in a supine (face up) position. Next the rescuer should begin CPR since compressions have been shown to be effective in clearing an obstruction. With each time attempt to ventilate, the rescuer should first look in the mouth to see if there is an object that can be pulled out of the airway with gloved fingers. Previously chest thrusts were taught for an obese or pregnant patient or a child with a foreign body airway obstruction. To simplify this procedure the Emergency Cardiac Care Guidelines 2005 recommend all patients receive chest compressions following CPR. For an infant, the rescuer uses back slaps before chest thrusts. Direct laryngoscopy and the use of Magill forceps may be required to remove a foreign object. If the object cannot be readily removed with these measures, an emergency cricothyrotomy, or emergency tracheotomy may be required. See: Heimlich maneuver