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(BQ) Part 2 book An atlas of head and neck surgery has contents: The larynx, the hypopharyn and the esophagus, vascular procedures, base of the skull surgery, microvascular surgery.
20 Indirect Mirror Laryngoscopy Anatomy of Superior Laryngeal Nerve (Fig 20-1) Highpoints See Chapter for additional discussion relative to peroral endoscopy Equipment: a Laryngeal mirror b Head mirror with light source or headlight c Gauze d Hot glass head device; hot water or forced hot air from small hair dryer Reassure patient: have him or her relax by drooping shoulders, easing neck muscles, and using moderate deep breathing Properly position the patient by having him or her sit erect, not slouch backward Topical anesthesia is required in 30% to SO% of patients: use a cotton swab moistened with 10% cocaine, % tetracaine, or % lidocaine Avoid use of compressed air spray, because too large a dose with cocaine may be administered Lidocaine 4% is probably the agent with the least side effects S Perform orderly visualization of: a Larynx with epiglottis, especially base of epiglottis b Hypopharynx, especially the pyriform sinuses and posterior wall c Base of tongue and vallecula Realize the optical illusions of the mirror: a Anterior commissure appears to be posterior (i.e., reversal of anterior and posterior regions) b There is no reversal of right and left sides c Overhang of epiglottis tends to obscure anterior commissure and base of epiglottis, a serious blind area d Overhang of ventricular bands tends to obscure ventricles e Overhang of vocal cords tends to obscure subglottic space The various relationships of the important nerves extrinsic to the larynx with relationship to the greater vessels are shown The internal branch of the superior laryngeal nerve passes through the thyrohyoid membrane on a line horizontal to the superior corner of the thyroid cartilage approximately cm medially (Lore, Sr.) FIGURE20-1 1069 Mirror laryngoscopy is a very important means of evaluation of the larynx, because it affords a full view of the entire presenting portion of the larynx, hypopharynx, base of tongue, and inferior tonsillar pillars Next in line are optical and direct rigid laryngoscopy with telescopic instruments or the operation microscope, followed by external palpation of the larynx Finally, radiographic examination, purely as an adjunct, is of aid in estimating subglottic extension of disease Plain soft tissue radiography, computed tomography (CT), and laminograms (planigrams) and laryngograms can be used and should be obtained before a biopsy sample is taken All patients with hoarseness must have a pathologic, anatomic, or physiologic reason for their symptoms However, tumors arising away from the free edges of the vocal cords may not and often not produce any voice changes in the early stages of the disease By the same token, recurrent laryngeal nerve paralysis is not necessarily associated with hoarseness For example, to say that a patient has no injury to the recurrent nerve, after thyroidectomy, simply because his or her voice is satisfactory is entirely fallacious The normal vocal cord many times compensates for and adapts itself to the paralyzed cord The only subjective complaint may be failure to control the pitch of the voice On the other hand, paralysis of the external branch of the superior laryngeal nerve is almost always associated with hoarseness The vocal cord is bowed and may be at a lower level than the normal vocal cord Paralysis of the recurrent laryngeal nerve can occur after endotracheal intubation Technique (Fig 20-2) A The patient is placed in an erect sitting position, preferably with the base of his spine resting against the back of a straight-backed examining chair The head should be free of any headrest, because the head and neck are usually not hyperextended The next step is to achieve complete relaxation The patient is instructed to let his or her shoulders, neck, and arms become limp Regular and moderately deep breathing aid in minimizing the gag reflex and spasm in the throat A suitable-sized laryngeal mirror-a selection from NO.3 to NO.6 is ideal-is chosen, depending on the oropharyngeal width The mirror is warmed either with a hot glass bead sterilizer (Premier Dental Products), hot water, or warm air from a blower, and its temperature is tested on the back of the examiner's hand The examiner, using an opened piece of x 2-inch gauze gently grasps the tongue between the thumb and middle finger, using the index finger to retract the upper lip The use of topical anesthesia will depend on the patient's ability to relax Diazepam (Valium), 10 mg, orally 30 minutes before examination aids relaxation significantly Complete visualization of the vocal cords will require phonation The vowel "E" is ideal If this fails to expose the vocal cords, have the patient attempt to laugh or sound "hah-hah-hah." Phonation is also necessary to check the function of the laryngeal structures as well as "open" the pyriform sinuses This is necessary to evaluate the mucosa of the pyriform sinuses The apex (inferior) portion of the pyriform sinus may not be visualized If suspicious results are found, direct rigid laryngoscopy will be necessary B Labeled parts are as follows: 1, epiglottis; 2, anterior commissure; 3, ventricular band; 4, posterior commissure; 5, corniculate cartilage overlying arytenoid cartilage; 6, cuneiform cartilage; 7, aryepiglottic fold; 8, glossoepiglottic fold; 9, ventricle; 10, base of tongue; and 11, pyriform sinus Some type of routine checklist should be followed to perform a complete evaluation, for example, the following: Larynx a Vocal cords (free edges and superior surfaces) and their motion and whether they are straight b Arytenoid cartilages and their motion c Ventricles and ventricular bands d Anterior and posterior commissures e Subglottic space; wall of trachea f Aryepiglottic folds g Lingual and laryngeal surfaces and free edges and base of epiglottis h Glossoepiglottic folds Hypopharynx a Pyriform sinuses-especially the inferior extent, the apex; constant filling with saliva indicates esophageal obstruction (Jackson's sign) b Posterior and lateral walls-the more superior portions can be visualized with a tongue depressor and an examining finger Tongue (must also be evaluated with an examining finger), especially base of tongue a Vallecula (space between epiglottis and base of tongue) b Juxtaposed inferior tonsillar pole C Bowing of the vocal cords This is best demonstrated during phonation of "E." It is usually caused by a prominent vocal process of the arytenoid cartilages (which can be amputated with stripping forceps) (see Fig 20-5) or paralysis or weakness of the cricothyroid THE LARYNX c D FIGURE 20-2 Sphincteric Group muscle, which is innervated by the external branch of the superior laryngeal nerve The vocal cord may be at a lower plane than the normal vocal cord D Bilateral adductor cord paralysis This indicates paralysis of either the cricoarytenoideus lateralis, interarytenoideus, or thyroarytenoideus or all these muscles bilaterally The nerve supply is via the adductor division of the recurrent laryngeal nerve The interarytenoideus muscle may have a motor supply via the internal branch of the superior laryngeal nerve This is dubious E Bilateral abductor cord paralysis This indicates paralysis of the cricoarytenoideus posterior muscles bilaterally Innervation is via the abductor division of the recurrent laryngeal nerve A way to remember easily the action of the significant intrinsic muscles of the larynx is to divide them into two groups: adductor or sphincteric group and abductor or dilator group An analysis of this group shows that it can be reduced to simple terms and can be described so it is easily remembered All these muscles pull on or are inserted into the arytenoids The cartilages of origin are the cricoid, arytenoids, and thyroid Hence, the letters C, A, and T may be used to designate the cricoid, arytenoid, and thyroid cartilages, respectively Dilator Group This is composed of a simple pair of muscles, namely, cricoarytenoid posterior, or CAP This pair abducts the cords Admittedly, this is an oversimplification of the diversity of opinion regarding the motor function of the intrinsic muscles of the larynx Details are beyond the scope of this atlas THE LARYNX Instruments (Fig 20-3) The Lore head light (Karl Storz) with observation side arm attachment is shown It was utilized with mirror laryngoscopy and nasopharyngoscopy both for examination and as a light source during surgery.The observer could see exactly what the examiner and operator visualized Its only drawback for the observer was the somewhat smaller image seen through the side arm This has been replaced with fiberoptic laryngoscopes that have either observer arms or video capabilities Direct optical, both flexible and inflexible, and direct rigid laryngoscopy and hypopharyngoscopy are described and depicted in Chapter The images seen on the optical instruments are in the same position as they are anatomically and are not reversed as they are with the mirror; that is, the anterior portion of the larynx and hypopharynx are visualized anteriorly while with the mirror the anterior portion of the larynx and hypopharynx are visualized posteriorly On both optical and mmor laryngoscopy the right and left sides are seen as they are in the anatomic position FIGURE 20-3 THE LARYNX Punch Biopsy of lesions of larynx and Hypopharynx (Fig 20-4) Additional endolaryngeal and microlaryngeal procedures are described in Chapter Highpoints Use topical anesthesia or general anesthesia plus topical anesthesia A small endotracheal tube (No.6) can be used Insert laryngoscope from the contralateral position through the mouth Stripping is preferred for lesions of the vocal cord except for bulky tumors, which are obviously malignant For details, see the section on direct laryngoscopy in Chapter and Figure 4-2 - With either a Holinger or a Jackson anterior commissure speculum or a standard laryngoscope introduced from the contralateral oral position, the lesion is exposed on the opposite side of the larynx Microlaryngoscopy is utilized for small lesions (see Fig 4-5D and E) With a sharp basket or cup forceps, the biopsy of the suspected area is performed in one or two locations, depending on the size of the tumor Postoperative bleeding is usually of no concern except with lesions involving the lingual side of the vallecula One such case of carcinoma had uncontrollable bleeding, necessitating an emergency laryngectomy Whenever general anesthesia is used, topical anesthesia is strongly recommended This permits a repeat mirror examination, prevents laryngospasm, and reduces the amount of general anesthetic agent and the danger of cardiac arrhythmias Toluidine blue, 1%, topically applied to suspicious lesions that are first cleansed with % acetic acid, has been demonstrated to be of some aid in localizing early carcinoma (Shedd and Gaeta, 1971; Strong et aI., 1968) FIGURE 20-4 THE LARYNX Stripping (De-Epithelialization) a Vocal Cord (Fig 20-5) of (Lore Sr., 1934) This author is concerned about the possibility that some cells, which may be precancerous or cancerous, could be vaporized or destroyed and thus missed on histologic examination Indications Highpoints Stripping of a vocal cord is preferred for virtually all lesions that involve primarily the true vocal cord Two exceptions are the bulky, obviously malignant tumor in which a simple punch biopsy suffices for diagnosis and the pedunculated, single, small polyp that may be removed with cup forceps The stripping operation is ideally suited for the removal of other polyps with or without associated edematous cords The polyp and edematous tissue are removed usually in one maneuver Papillomas, hypertrophic vocal cords (polypoid edematous cords), and almost any benign lesion may be thus removed The resulting free edge of the cord remains straight, and re-epithelialization occurs in to weeks Usually, only the surface epithelium needs to be removed; however, if necessary, one may go as deeply as the thyroarytenoid muscle or may operate several times if some diseased tissue has been left Stripping a vocal cord is particularly suited to suspiciously malignant disease (e.g., leukoplakia or keratosis), which extends over a greater part of the cord or the entire length of the cord By stripping the entire cord, the entire lesion may be removed and serial sections taken by the pathologist for microscopic examination Hence, a complete evaluation of malignancy is possible If the lesion turns out to be benign, satisfactory removal has been achieved and no additional operation is necessary Miller has shown that this technique appears to be satisfactory for carcinoma in situ The author agrees; others believe that a simple cordectomy is warranted Lengthy lesions of the ventricular bands or in the floor of the ventricles are also well suited to the stripping procedure Subglottic tumors are easily sampled with the child-sized stripping forceps Essentially, this is the lmperatori subglottic forceps, which was modified by Lore, Sr by making the anterior two thirds very sharp and the posterior third somewhat duller A subsequent modification (Lore, Jr.) utilizing a telescope is manufactured by Karl Storz (see Chapter 4) Bowing of a vocal cord by a prominent vocal process of the arytenoid cartilage may be improved by inclusion of the vocal process in the stripping forceps Carbon dioxide (C02) laser removal of these lesions is preferred by some surgeons (Strong and Jako, 1972) General anesthesia supplemented with topical anesthesia is preferred Indiscriminate use and overdosage of a muscle relaxant is definitely contraindicated, because the cord will be so relaxed when stripped that bowing or an irregular free edge of the cord will result This danger cannot be overemphasized A small endotracheal tube at the posterior commissure is ideal for an unhurried procedure Contralateral approach with anterior commissure speculum is usually necessary Be certain that the amount of tissue grasped is to the desired depth and extent Attempt to complete the operation in a single maneuver Strip only one vocal cord at a time One month should elapse before stripping the opposite side in bilateral disease; otherwise webbing at the anterior commissure may occur This admonition applies where the de-epithelialization extends to the anterior commissure If intact mucosa remains for several millimeters at the anterior commissure, then bilateral stripping may be done Microlaryngoscopy is advantageous, especially for small lesions suspected to be malignant (see Fig 4-50 and E) A If the left vocal cord is being operated on, the anterior commissure speculum is introduced from the right side of the mouth The beak of the instrument extends to the anterior commissure and may be slightly rotated so that the beak is against the right cord The left cord is thus fully exposed and fixed With the instrument in this position a full view of the cord is obtained and the floor of the ventricle, in most cases, is brought into view Byinserting the instrument slightly between the cords, a subglottic lesion may be seen and a biopsy of it performed The free edge of the vocal cord can be "rolled" laterally This may also facilitate stripping the inferior portion of the vocal cord The left-sided stripping forceps (the lower or medial blade fixed, the upper or lateral blade hinged) is inserted with the long axis of the blade parallel to the long axis of the cord An adult (9 mm) or child (6 mm) blade is selected as required THE LARYNX A B c FIGURE 20-5 B The blade is opened and the growth and subjacent cord are engaged gently The blade is placed between the anterior commissure and the vocal process of the arytenoid The vocal process is usually not included unless the procedure is performed for bowing of the vocal cord due to a prominent vocal process Slight traction is made toward the free edge until the growth itself is felt in the forceps Then the forceps is closed tighter At this stage it is important to visualize the cord to make sure thilt not too much is being removed If too much tissue is engaged, the forceps is opened a little until the proper amount of tissue is included The stripping is then begun anteriorly by tilting the handle of the forceps posteriorly The entire stripping is performed with a brisk, rapid, single motion C The position of the forceps at the end of the single stripping motion is shown D A schematic depicted in C lateral view is similar to the stage Gross examination of the tumor will reveal a thin small strip of cord tissue attached to it anteriorly and posteriorly Postoperatively, the patient is allowed to speak in a normal manner Excess speech, whispering, shouting, and singing are contraindicated for to weeks Normal speech is allowed The voice is usually very clear immediately postoperatively Some hoarseness may occur several days later for a short period of time In hypertrophic laryngitis (polypoid involvement of the entire vocal cord), caution should be taken not to leave a tab of polypoid tissue either at the anterior portion of the vocal cord or in the vicinity of the vocal process of the arytenoid Extreme caution must be taken in this disease not to de-epithelialize the anterior portion of the contralateral vocal cord; otherwise webbing may occur THE LARYNX Endoscopic Removal of Congenital Cyst of Ventricle in Newborn (Internal Laryngocele) (Fig 20-6) Cysts of the larynx may be congenital or acquired The congenital cyst that arises in the ventricle is often indistinguishable clinically from a laryngocele A true laryngocele is a diverticulum of the mucosa of the ventricle lined with respiratory epithelium, usually with a communication to the laryngeal lumen Thus, a laryngocele may fill with air or mucus and may be internal, entirely within the lumen of the larynx and presenting as a cystic mass from the ventricle, or external, extending through the thyrohyoid membrane and presenting as a compressible cystic mass in the lateral side of the neck between the hyoid bone and the thyroid cartilage The internal laryngocele can usually be deflated and removed through an endoscope, whereas the external laryngocele is excised through an external cervical approach A horizontal skin incision is made over the cystic mass, which is dissected down to the thyrohyoid membrane Extreme care must be exercised not to injure the internal branch or external branch of the superior laryngeal nerve (see Fig 20-25) For all practical purposes the congenital ventricular cyst and internal laryngocele in the newborn present the same clinical picture of varying degrees of respiratory obstruction and absent or poor cry at birth The treatment is the same and often is very urgent Attempt immediate removal of laryngocele through the laryngoscope If this is not possible, aspirate and deflate cyst with needle or punch Avoid tracheostomy in a newborn; however, not hesitate to perform one if endoscopic methods fail Tracheostomy in infants younger than year of age is associated with high morbidity and mortality The alternative is endotracheal intubation Extubation may require the anterior cricoid split of Holinger and colleagues (see p 1016) A The larynx is exposed with a wide lumen laryngoscope A laryngeal grasping forceps is inserted through the loop of a very fine snare An ideal snare is the type used in rectal surgery for the removal of rectal polyps in infants The cyst is grasped firmly and pulled upward while the snare engages the neck or base of the cyst Speed is essential, especially because the cyst may break and mucus may be extruded The snare is closed, cutting the neck of the cyst, and the forceps are withdrawn with the cyst Tracheal suction may be necessary if aspiration of mucus occurs This procedure requires the aid of an assistant who holds either the laryngoscope or preferably the forceps after the operator has grasped the cyst A Lewy laryngoscope holder, although large, may be of help B A schematic cross-sectional technique Highpoints All newborns with respiratory difficulty and abnormal or absent cry must undergo laryngoscopy FIGURE 20-6 view demonstrates the THE LARYNX CO2 Laser in Laryngeal and Endobronchial Surgery (See Fig 4-6) The CO2 laser has innumerable applications in head and neck surgery It can be utilized via the microscope or a hand-held adapter All of the various adaptations of this modality are beyond the scope of this atlas but have been described by many authors Ossoff and Karlan, in Ballenger's Diseases of the Nose, Throat, Ear, Head and Neck (1985, chap 42), give an excellent overview of this subject (see also Chapter of this atlas) Basically, this form of energy can be used to vaporize tissue or for dissection purposes The device can be utilized in two modes, either pulsed or continuous, and operates at a wavelength of 10.6 flm, producing light in the invisible range of the spectrum Microlaryngoscopy Using the CO2 Laser Indications • • • • Papillomatosis Various degrees of keratosis Other benign and premalignant lesions Selected patients with verrucous carcinoma who refuse surgery • Soft and/or edematous tissue and some localized fibrosis that is causing obstructions • Capillary hemangiomas Other Indications Reported by Other Authors • Debulking large malignant lesions to improve the airway (the present authors would opt for preoperative chemotherapy as an initial step) Debulking is not a definitive treatment (JML) • Webs and noncircumferential scars • Carcinoma in situ-no specimen margins-not recommended (JML) • T1 carcinomas of the true vocal cord and epiglottis no specimen margins-not recommended (JML) • Arytenoidectomy Endoscopic Removal of Small Noncircumferential Tracheal Scar Ossoff et al (1985) described stenosis: Granulation three stages of tracheal stage Limited scarring Extensive scarring They believe the CO2 laser is useful in the first and second stages but not in the third stage It is of virtually no value in treatment of complete thick circumferential scars of the trachea Highpoints and Precautions Fire is an ever-present complication that must always be kept in mind in any application of the CO2 laser Fire may act as a blowtorch from the trachea and larynx The endotracheal tube must be immediately removed and the procedure terminated; then a new endotracheal tube is introduced In the presence of increasing concentration of oxygen, the heat produced by this laser can result in the ignition of any combustible material Prevention of this catastrophic sequela is based on the following: Provide special training for surgeons and all personnel Use a specially coated "laser" endotracheal tube; alternatively, use a tube (preferably red rubber) carefully wrapped in overlapping fashion with protective V2-inch metallic tape Water or methylene blue rather than air is used to inflate the cuff of the endotracheal tube Care must be taken that the tape used is in fact metallic rather than plastic tape with the appearance of metallic tape The authors have noticed that one flexible metal endotracheal tube that we have tried actually leaks Use a nonflammable anesthetic agent Use water-saturated cottonoid pledgets over the wrapped endotracheal tube in the laser field and in the subglottic space These pledgets are to be kept moist during the entire procedure Retrieval sutures are secured to these pledgets The sutures, however, may be vaporized with the laser; hence, an accurate count of the pledgets at the close of the operation is mandatory Protect all exposed skin and mucous membrane of the patient with wet towels and sponges even outside the operative field Protect the patient's eyes with glasses and two layers of wet towels Corneal and scleral burns can occur both to the patient and to operating room personnel Protect all personnel in the operating room with glasses Place a notice on the operating room doors stating that a laser is in use and that personnel should not enter unless glasses are worn Be cognizant that the laser beam is absorbed by soft tissues and bone but that it may be reflected by metal objects 10 Check that the laser beam exactly coincides with the target light on a wooden block just before the use of the laser 11 When using the CO2 laser on a bilateral lesion, it is advisable to treat one side at a time 12 During laryngeal surgery, the subglottic area is completely occluded around the endotracheal tube THE LARYNX with soaking wet cotton sponges and sutures to facilitate retrieval Comments Basically, this form of energy can be used to vaporize tissue or for dissection purposes It can be utilized in two modes, either pulsed or continuous, and operates at a wavelength of 10.6 nm, producing light in the invisible range of the spectrum Although many authors use the CO2 laser for excisional biopsy purposes, this author has not followed this procedure for fear of possibly destroying tissue for histologic examination Surgical biopsy is preferred This is a personal preference There is little doubt that minute areas are best sampled surgically either using telescopic biopsy forceps (see Chapter 4) or the microscopic laryngeal set-up Only vessels less than mm in diameter should be attempted to be coagulated with the laser; hence, care must be taken when excising larger lesions that may have large vessels Under these circumstances electrocautery and/or pistol grip-type hemostatic surgical applicator clips should be available Although the use of the CO2 laser usually requires the larger lumen laryngoscope, as used in microlaryngoscopy, occasionally it is well nigh impossible to insert these large laryngoscopes The authors h"ve occasionally used the standard Holinger hourglass speculum or the Jackson anterior commissure speculum with monocular vision This adaptation requires a careful preoperative trial to be certain that the laser beam is aligned with the target spot on a block of wood The one area that the authors find very difficult to treat with the laser is posterior to the vocal process of the arytenoid and the posterior commissure because of the posterior location of the endotracheal tube One solution is the use of a 1.3-cm segment of a plastic tooth guard that is firmly secured with heavy silk sutures to the anterior aspect of the laryngoscope The concave portion of this segment is faced anteriorly to hold the endotracheal tube at the anterior commissure This segment is then completely covered with a water-saturated cottonoid pledget to prevent ignition Another adaptation of this concept would be the use of a metallic clip shaped similar to a portion of the tooth guard to hold the endotracheal tube anterior to the laryngoscope Despite the reports of minimal postoperative edema that may cause airway obstruction, it is best to observe the patient very carefully after extubation The patient may be kept in the hospital overnight to be observed for 18 hours if there is any suspicion of edema, in which case corticosteroids are used Pain and scarring are reported as uncommon or entirely absent after the use of the CO2 laser Although we have not seen pain as a complication of endolaryngeal laser use, scarring forming a web at the anterior commissure has occurred when papillomatosis crosses the anterior commissure This has not been of any significance or concern, but it can occur Pain with scarring has occurred with the use of the CO2 laser in the floor of the mouth in at least one patient With a hand-held CO2 laser, debulking of massive lymphohemangiomas of the tongue has been utilized to vaporize the lesions with varying success Whether these lesions arise in the tongue or larynx their treatment usually requires surgical excision along with laser surgery Complications • Fire • Edema-usually to hours postoperatively • Postoperative bleeding after vaporization of large lesions • Recurrence of lesions • Corneal, mucous membrane, and skin burns • Tracheal perforation and burns • Glottic web • Vocal cord fibrosis from vaporizing the underlying vocalis muscle • Subglottic stenosis • Arytenoid perichondritis-use antibiotics if cartilage is exposed • Delayed airway obstruction • Foreign bodies from metallic tape or dislodged cottonoid pledgets It is obvious from this list of complications that significant expertise and care is necessary with the use of the CO2 laser This procedure is not recommended for the occasional operator or the occasional anesthesiologist Endoscopic Intracordal Injection of Teflon Paste (Fig 20-7) When there is a glottic gap of mm or more resulting in dysphonia and/or aspiration, intracordal injection of various types of materials has been described to narrow this gap The most common indication is adductor vocal cord paralysis in which the normal vocal cord is unable to approximate the fixed abducted vocal cord The timing of performing the intracordal injection varies with the underlying etiology and whether sufficient time has elapsed for spontaneous recovery of the paralyzed vocal cord (usually to 12 months) and also whether other procedures are indicated In general, the treatment of dysphonia can be delayed whereas the treatment of aspiration may be urgent Then again other methods of management of aspiration may be indicated, such as cricopharyngeal myotomy (which has varied success) and closure of the glottis ... head and neck cancers and 1.5% of all cancers The trend during the period 19 92- 1998 appears to be somewhat downward: 4 .2 to 3 .2 The bulk of patients are in the sixth and seventh decades of life... 0. 022 2 0.0431 0.0689 0 .27 84 0.6313 2. 1783 4.6134 10.3436 18.9683 27 .1383 34.5380 38.0 920 36.3899 33.0439 25 . 020 0 0.0103 0.0000 0.0115 0.0000 0. 022 8 0.0404 0. 127 0 0.3340 0.5887 1.1518 2. 18 92 4.4506... surfaces) and their motion and whether they are straight b Arytenoid cartilages and their motion c Ventricles and ventricular bands d Anterior and posterior commissures e Subglottic space; 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