Nasoendoscopy Anatomy Fiberoptic nasoendoscopy provides incredible visualization of the perilaryngeal structures as well as the vocal cords and glottic opening. It can easily be accomplished with a short rhinolaryngoscope in a cooperative patient, with minimal or no topical anesthesia, assuming a high level of operator skill.  Flexible fiberoptic intubation techniques have a very limited role in emergency airway management, and no role in rapid sequence intubation, given the time requirements of this procedure.  They can be very valuable, however, in situations where the oral route is blocked and there is a clinical need to visualize the larynx as part of patient assessment.  Examples include angioedema, airway burns, and other intra-oral and laryngo-tracheal pathology. Although intubation with a fiberscope is rarely done, there are frequent opportunities for nasoendoscopy in a busy emergency department.  It is routine in ENT clinics. When viewing the larynx with a fiberscope, the three dimensional nature of the laryngeal inlet, and the significance of the epiglottis become evident.  Structures close to the imaging end of a fiberscope take on a fish-eye distortion.  When recognized from a distance, they are more recognizable. The amount of light projecting from a fiberscope also influences how far away structures can be recognized.  Fiberscopes are made up of individual imaging fibers (normally of glass, some use plastic). To display the image from an eyepiece, an endoscopic coupler and camera are used.

In this view of the larynx obtained with an Olympus ENF-P4 nasopharyngoscope, the larynx is shown with breathing (left image, cords abducted) and the with phonation (cords adducted):
• the wide arrowheads mark the  left aryepiglottic fold
• the asterisk is at the interarytenoid notch
• the round dots mark the right posterior cartilages (cuneiform and corniculate cartilages)

The normal orientation for a nasopharyngoscope is to have the epiglottis (anterior) at the bottom of the image, and the posterior cartilages at the top.  This image has been flipped to match the perspective with direct laryngoscopy (epiglottis at top).  The small black notch on the bottom perimeter of the image is part of the scope eyepiece; it lets the operator determine the orientation of the scope, and an endoscopic camera on the eyepiece.

Notice that interarytenoid notch and posterior cartilages make up the most posterior (and most caudal) structures of the laryngeal inlet.  Fiberoptic instruments provide a better view of the inner larynx than is typically seen at direct laryngoscopy.

With the evolution of miniature CMOS video cameras, the camera is now small enough to be directly placed on the distal tip of the scope. An articulating lever still allows control like a standard fiberscope, but instead of glass bundles running the length of the scope, an electrical connection sends the digital video signal directly to an imaging screen.  These video scopes offer amazing high resolution imaging of the larynx. The sequence of shots below is from an oral (not nasal) insertion of the video scope, and the orientation of the larynx is reversed from the above images; now the apex of the vocal cords is pointing down, the epiglottis (anterior) is at the bottom of the screen.

Front left to right in the first row the uvula, tonsils, and epiglottis are seen.  In the second row of images the scope has moved to and beyond the epiglottis, showing the glottic opening.  In the last row of images the vocal cords are open, closed, and open, respectively, showing closure of the interarytenoid notch and the coming together of the posterior cartilages (and vocal cords) with phonation.