When we intubate a patient, all we really want to do is place the endotracheal tube in the glottis. Let’s face it, the glottic opening can be a tough feature to locate on a good day, let alone wh
en things just aren’t going well. Blood, vomit, laryngospasms, edema; you know the drill. If you want to find the glottis, stop looking for the glottis. What? Read on, friends, I’ll show you.
Anatomy of the Larynx
The larynx is made up of three single cartilages and three pairs of cartilages.
The thyroid is the largest of the laryngeal cartilages. It’s within this cartilage that the glottis is located. The anterior ends of the vocal cords are attached to the thyroid cartilage. This feature gives us the ability to directly move the glottis to improve our view. Known by different names, external laryngeal manipulation (ELM), backward upward rightward pressure (BURP), digital physical laryngeal manipulation; the procedure of manipulating the thyroid cartilage to optimize the glottic view has been described for many years.(1–3)
The cricoid cartilage, the most inferior of the laryngeal cartilages, is the only laryngeal cartilage that’s a complete ring. In pediatric airway, the cricoid cartilage is the narrowest part of the airway. Non-cuffed tubes fit snuggly into the ring to prevent air leak. Cricoid pressure has been used to improve glottic view during laryngoscopy, but I think you will find that laryngeal manipulation does a better job of optimizing the glottic view. One of the very best studies I’ve read on the use of cricoid pressure was published in 2007. The authors concluded, “We recommend that the removal of cricoid pressure be an immediate consideration if there is any difficulty either intubating or ventilating the ED patient.”(4) As an airway professional, you owe it to yourself to read the entire study.
Let me now introduce to you, straight from the back of the tongue—the most important airway landmark, the intubator’s very best airway friend, the gateway to the glottis—THE EPIGLOTTIS!
Remember when I told you to stop looking for the glottis? I want you to start looking for the epiglottis. Remember from our last lesson that the inferior (extrinsic) tongue muscles are connected to the mandible, hyoid and epiglottis. We can use that connection to locate the epiglottis. I’ve found the epiglottis to be easier to locate on a more reliable basis for both novice and experienced providers. Sounds like a study in the making.
Try this: Insert the laryngoscope blade into the patient’s mouth and just follow the tongue posteriorly until you locate the epiglottis. Lift the epiglottis and there’s the glottic opening. Most of the time, it’s just that easy.
The second best friend of the intubator is the group of three pairs of cartilages, which lie along the posterior border of the glottic opening; the corniculate, cunneiform and aryetnoid cartilages. The arytenoids sit on top of the posterior portion of the cricoid cartilage. The posterior end of each vocal cord is attached to an arytenoid cartilage. The length and medial-lateral positioning of the vocal cords are accomplished by movements of the arytenoids. The arytenoids can’t be seen in the standard laryngospic view because they’re buried in tissue.
The corniculates sit on top of the arytenoids and are seen during laryngoscopy immediately lateral to the interarytenoid notch. The cureiform are embedded in the aryepiglottic folds. They give support to these membranes, which connect the arytenoids to the epiglottis. In the standard laryngoscopic view, the cuneiform can be seen immediately lateral to each of the corniculates.
Collectively these cartilages go by a variety of names: the arytenoids, posterior cartilages, nodes. Regardless of which term you use, know that they are the posterior border of the opening to the glottis and are identified by a notch in the middle and two pairs of bumps on either side.
So there you are. Your new best intubation buddy is the epiglottis, and your second best buddy, the posterior cartilages. I find it ironic that these most helpful features lay right behind our nemesis, the tongue. A good knowledge of the airway anatomy is really a roadmap to success. Bust open that A&P book that you’ve got shoved up there on the shelf. It will make you a better provider.
Take care and be safe.
1. Benumof JL & Cooper SD. Qualitative improvement in laryngoscopic view by optimal external laryngeal manipulation. J Clin Anesth. 1996;8(2):136–140.
2. Knill RL. Difficult laryngoscopy made easy with a “BURP.” Can J Anaesth.1993;40(3):279–282.
3. Levitan RM, Mickler & Hollander JE. Bimanual laryngoscopy: A videographic study of external laryngeal manipulation by novice intubators. Ann Emerg Med. 2002;40(1):30–37.
4. Ellis DY, Harris T & Zideman D. Cricoid pressure in emergency department rapid sequence tracheal intubations: a risk-benefit analysis. Ann of Emer Med. 2007;50(6): 653–665