A non-derivative, non-surgical tracheostomy: the translaryngeal method

OBJECTIVE

To present a new technique for non-surgical tracheostomy.

DESIGN

An open, clinical trial on patients requiring elective tracheostomy.

SETTING

Intensive care unit of a community hospital.

PATIENTS

95 adults, mean age 60 years, and 14 infants and children, mean age 26 months (2 months-7 years) with common indications for tracheostomy.

INTERVENTION

Through a needle inserted in the trachea, a guidewire is pushed out of the mouth against the usual direction and attached to a special device formed by a flexible plastic cone with a pointed metal tip joined to an armoured tracheal cannula. This device is then pulled back through the oral cavity, larynx and trachea and outwards across the neck wall by the operator applying traction on the wire with one hand and counterpressure on the neck wall with the fingers of the other hand. When the cone and a part of the cannula have emerged, the cannula is cut off from the cone, straightened perpendicular to the skin, rotated and advanced caudally to its final position.

RESULTS

The cone-cannula passed smoothly through the vocal cords. The metallic point perforated the neck easily. The dilation did not present any risk of tracheal wall damage because the direction of the manoeuvre was from the inside to the outside of the neck. The tissues tightly adhered to the cannula, thus avoiding infection and bleeding. The use of ventilation systems permitted utilization of translaryngeal tracheostomy (TLT) even in patients for whom apnoea might have carried some risk, because there is no interruption of respiratory assistance during the procedure. Follow-up showed no late obstructive complication at the level of the tracheostoma.

CONCLUSIONS

By virtue of its greater safety and less trauma to tissues than percutaneous techniques, TLT can also be carried out in infants and children (an important benchmark for any tracheostomy technique) and in very difficult patients from whom other techniques have serious drawbacks.

Use of breath sounds to assist difficult intubation of the trachea

The technique of locating the laryngeal inlet using breath sounds was attempted on six patients referred for appropriate management following a failed intubation at the Eldoret District Hospital. Five of these were successfully intubated. It was still impossible to intubate the sixth patient who subsequently required a tracheostomy.

The normal pediatric larynx on CT and MR

PURPOSE

To determine the MR and CT appearance of the normal pediatric larynx.

METHODS

Fifteen CT scans and 15 MR examinations of children with normal larynges and airways were reviewed retrospectively. Characteristics that were noted included the level of the hyoid bone, calcification and signal intensity within separate laryngeal components, amount of paraglottic fat, anteroposterior airway diameters, and airway contours. Two cadaveric larynges were imaged by CT and MR and were then sectioned at corresponding levels and section thicknesses.

RESULTS

The larynx is higher in children than in adults, with the hyoid bone found at the C2-3 level in the youngest children (newborn to 2 years). The subglottic airway was narrowest in the youngest children. The hyoid bone was the only laryngeal structure ossified in any of the children. A thin line of high density was seen in the expected location of the thyroid cartilage in some children. The featureless circumferential soft tissue seen around the airway represented the uncalcified laryngeal cartilaginous structures. This was confirmed on gross sectioning of cadaveric larynges. The supraglottic airway contour was triangular or oval, the glottis was shaped like a teardrop, and the subglottic contour was oval. Contours were confirmed on histologic examination of necropsy specimens.

CONCLUSIONS

This preliminary study suggests that the pediatric larynx differs from the adult larynx with respect to size, position, consistency, and shape, and these differences are reflected on CT and MR studies.

Subglottic branch of the superior laryngeal nerve in the dog penetrates the cricoid cartilage

The topographic anatomical study on the distribution pattern of the superior laryngeal nerve (SLN) in the larynx was studied in thirteen adult dogs. The ramus posterior of the SLN divides into two branches; the interarytenoid branch (IA) and the pharyngoesophageal branch (PE). The IA on both sides connect to the cricoid ganglion (CG) in the midline at the cranial border of the cricoid cartilage. Posterior glottic branches arise from the IA, run over the cricoid cartilage, and distribute fibers to the posterior wall of the glottis. Every specimen observed in the present study possessed the CG and the posterior glottic branches. The subglottic branch derives from the IA near the cricoid ganglion, and passes through the cricoid foramen (CF) (Yoshida, 1986). The subglottic branch distributes fibers to the subglottic mucous membrane covering the cricothyreoid ligament. The CF and the subglottic branch were observed on both sides of seven specimens out of thirteen dogs. They were also observed on only one side in three specimens, and were not detectable on either side in the three remaining specimens. The silver impregnation applied in the semimicroscopic dissection facilitated identification of the precise localization and the topographic arrangement of ganglia and nerve bundles.

Functional anatomy of forebrain vocal control pathways in the budgerigar (Melopsittacus undulatus)

Budgerigars throughout life are capable of learning to produce many different sounds including those of human speech. Like humans, budgerigars use multiple craniomotor systems and coordinate both orosensory and auditory feedback in specialized forebrain nuclei. Although budgerigar auditory-vocal learning has a different evolutionary origin from that of human speech, both the human and budgerigar systems can control F0 and can alter the distribution of energy in spectral bands by adjusting the filter properties of the vocal tract. This allows budgerigars to produce an extremely diverse array of calls including many broadband and highly complex sounds.

Borders and topographic relationships of the paraglottic space

The precise topographic relationships of the paraglottic space (PGS) were investigated in serial plastinated or frozen whole-organ sections of 46 normal adult larynges. Laterally, the PGS was bordered by the thyroid cartilage. Superomedially, the PGS in some specimens was only separated from the periepiglottic space by a coherent collagenous fiber septum. The paraglottic adipose tissue extended between the caudal fibers of the thyroarytenoid muscle. Inferomedially, the PGS was bordered by the conus elasticus. The anteroinferior portion of the PGS extended beyond the larynx beneath the inferior rim of the thyroid cartilage. Posteroinferiorly, the paraglottic adipose tissue extended towards the cricoarytenoid joint. Dorsally, the PGS was bordered by the mucosal lining of the piriform sinus. Due to the intimate topographic and histologic relationships present, cancer involving the PGS may rapidly infiltrate all adjacent anatomic structures.

Plastination of the larynx for whole-organ sectioning

Whole-organ sectioning is an important technique for the assessment of laryngeal pathology. Since currently established methods require prior decalcification which causes morphological changes, the critical border area between cartilage and surrounding soft tissue cannot be investigated in the same specimen and morphometric studies are not possible. Plastination is a laboratory technique that has previously demonstrated its capacity to overcome these shortcomings. In so doing water and lipids are replaced by curable polymer within the laryngeal cells making decalcification unnecessary. In the present study, more than 50 human larynges were processed using block plastination (BP) and sheet plastination (SP). For BP the complete organ was plastinated as a whole and then cut into thin serial sections. For SP the fresh organ was sliced first and plastinated in a second step. Findings demonstrated that SP allowed for the production of whole-organ sections within a period of 1 week only. Section thicknesses were as thin as 15 mm using a diamond wire saw and an ultramilling device. Sectioning was possible in both coronary and horizontal planes. Following BP, specimens were cut in an industrial cutting machine to thicknesses of about 0.6 mm. Shrinkage of tissue was less than 10% for both methods. In all, SP was technically superior to routine paraffin histology, although cutting equipment is very expensive and delicate in handling. At present the technique of BP is the method of choice for macromorphometrical investigations on serial sections of the human larynx.

The effect of laryngeal mask airway insertion on the position of the internal jugular vein

A high-quality ultrasound system (Dyasonics Prisma) was used to study the effect of laryngeal mask airway insertion and cuff inflation on the position and relations of the internal jugular vein in eight healthy young patients undergoing elective surgery. On insertion of the laryngeal mask, with the cuff pre-inflated with 10 ml of air, some minor movement was discernible in the larynx. Neither the larynx nor surrounding structures changed significantly in position. However, on full inflation of the laryngeal mask cuff there was a more noticeable movement of the larynx, which visibly distended in an anterior direction. The mean anterior displacement was 0.8 cm (range 0.6-1.1 cm). There was no significant lateral displacement of the carotid artery or internal jugular vein and there was no significant compression of these structures. We conclude that in the presence of a laryngeal mask airway fixed landmarks such as the sternal notch and angle of the jaw should be used to identify the likely position of the internal jugular vein. Difficulty in cannulation may be experienced if the mobile laryngeal structures are used as landmarks.

Laryngeal adjustment in whispering magnetic resonance imaging study

Previous studies confirmed that during whispering the glottis is kept open to prevent vocal fold vibration and the supraglottal structures are constricted. However, there has been no study exploring the exact contour of the laryngeal lumen in the frontal dimension during the production of whispering. In order to further elucidate the nature of the laryngeal adjustments regarding the contour of the laryngeal lumen in whispering, and the role of supraglottal constriction in particular, we conducted a physiological study using magnetic resonance imaging. According to the results, the supraglottal structures were not only constricted but also shifted downward, attaching to the vocal fold to prevent vocal fold vibration completely during whispering. The results suggested the underlying mechanism of suppression of vocal fold vibration during the production of whispering.

Anatomy, physiology, and development of feeding

Dysphagia in infants and children is usually only one part of a broad spectrum of complex medical, health, and developmental problems. As etiologies vary, so do prognoses. Increased survival rates of infants in recent years have been accompanied by an increased prevalence of neurologic, cardiorespiratory, and structural impairments that can affect nutritional status and feeding function. Knowledge of anatomy, physiology, and normal development of feeding skills is basic to the assessment and management of pediatric dysphagia.

The posterior cricoarytenoid ligaments and their relationship to the cadaveric position of the vocal cords

Much debate has occurred over the last century regarding the reason for the cadaveric position of the membranous vocal cord. This study attempts to identify the determining factors of the position of the vocal cord. Serial dissection of 36 cadaveric larynges was carried out and laryngeal measurements taken. The cadaveric position of the vocal cords was correlated to that of the posterior cricoarytenoid ligaments and it was found that the two were directly related. The study shows that the major determinant of the position of the denervated vocal cord is the position of the posterior cricoarytenoid ligament.

Correlations between call characteristics and morphology in male cricket frogs (Acris crepitans)

We investigated the relationships among spectral and temporal advertisement-call characteristics and the sizes of the laryngeal and ear components thought to underlie the generation and reception of species-specific vocalizations in male cricket frogs (Acris crepitans). We tested the predictions that the volumes of the structural elements necessary for acoustic communication would be correlated with various parameters of the vocalizations. The anatomy of laryngeal and ear structures was reconstructed from serial sections of the heads of male cricket frogs of two subspecies collected from several sites across the range of this species in Texas, USA. The relationships among the anatomy and call parameters were assessed using several univariate and multivariate analyses. Highly significant univariate correlations among the laryngeal components suggest that the temporal and spectral characteristics of the calls are not independently produced. Dominant frequency correlates strongly with most of the other call and morphological characteristics. Removing body size effects, however, removes the relationship between dominant frequency and the volume of the whole larynx and ear. This is also the case for call pulse rate, indicating that for this species both spectral and temporal call parameters are biomechanically related to laryngeal size which is, in turn, largely mediated by body size. General body size effects might also explain the existence of significant relationships between ear size and temporal characteristics of the call that probably do not have a functional basis.

Assessment of mucosal underdosing in larynx irradiation

PURPOSE

Mucosal underdosing as a result of electron disequilibrium at the air cavity may affect local recurrence rates for T1 and T2 larynx cancers. Secondary build-up properties of high-energy beams have been demonstrated in a slab phantom. It was the aim of this investigation to determine whether significant surface underdosing exists for the mucosa under clinical conditions.

METHODS AND MATERIALS

Measurements were made using a thermoluminescent dosimetry (TLD) extrapolation technique in an anatomic larynx phantom. The larynx phantom was constructed using tissue and cartilage equivalent material, based on patient cross-sectional anatomy. Three different thicknesses of LiF ribbons, 0.14, 0.39, and 0.89 mm, were placed reproducibly at 12 different positions at the anterior, posterior, and lateral walls on the endolarynx surface. Measured doses were plotted and an extrapolation was made back to the mucosal depth to obtain the dose received at each of the positions. Results were obtained for two different field configurations, opposed laterals and oblique fields, for 6-MV X rays and opposed lateral fields from a telecesium unit. In addition, the larynx surface doses of field sizes from 4 x 6 cm2 to 7 x 6 cm2 were investigated.

RESULTS

Surface underdosing was observed owing to the secondary build-up and build-down effect of the air cavity, and the dose measured for the three extrapolation TLDs at any position varied by up to 18%. An average variation of 6% was observed. The surface underdosing was most apparent for the 6-MV opposed lateral beam technique, where mucosa doses down to 76% of the prescribed dose were observed. Mucosal underdosing at the measurement positions was less marked with oblique techniques, telecesium treatment, and increasing field size.

CONCLUSION

Because of underdosing, some surface positions receive < 80% of the prescribed dose. This may contribute to the potential for higher recurrence rates observed with high-energy photons.

[Assessment with magnetic resonance of laryngeal and oropharyngeal movements during phonation]

The latest MR units are provided with the Turbo-Field-Echo technique which permits gradient-echo imaging with very short TE and TR and is optimized to yield the highest possible image quality within a very short acquisition time--i.e., less than 5 seconds. This dynamic study was aimed at depicting normal laryngeal and oropharyngeal movements during maximal inspiration and the prolonged uttering of vowels, in both a normal and a loud voice. We examined 10 healthy volunteers (7 men and 3 women) with an 0.5-T superconductive unit (Gyroscan T5 III, Philips Medical System). We used Turbo-Field-Echo sequences with the following acquisition parameters: TR 12 ms, TE 6 ms, flip angle 30 degrees, 4 acquisitions, acquisition time: 5 seconds. A single coronal scan was acquired at the larynx, while a midsagittal scan and 2 coronal scans were acquired at the oropharynx. The volunteers were asked to breathe in long and deep, to prolong the emission of the vowel [i] during laryngeal studies and to prolong the emission of the fundamental vowels [a], [i] and [u] in a normal (50 db) and a loud (70 db) voice during oropharyngeal studies. The movements of true and false vocal cords were clearly depicted in all the volunteers, and the activity of the different anatomical structures of the oropharyngeal cavity (lips, tongue, hard and soft palate, pharynx and epiglottis) was also demonstrated. During vowel production in a loud voice, the vocal tract was enlarged at the oral cavity for the vowels [a] and [u] and at the pharynx for the vowel [i]. To conclude, fast MRI with midsagittal scans is the best imaging modality to study different vocal tract patterns during speech and can thus replace midsagittal radiography and xeroradiography in the study of vowel production.

Preoperative airway assessment: predictive value of a multivariate risk index

Using readily available and objective airway risk criteria, a multivariate model for stratifying risk of difficult endotracheal intubation was developed and its accuracy compared to currently applied clinical methods. We studied 10,507 consecutive patients who were prospectively assessed prior to general anesthesia with respect to mouth opening, thyromental distance, oropharyngeal (Mallampati) classification, neck movement, ability to prognath, body weight, and history of difficult tracheal intubation. After induction of anesthesia, the laryngeal view during rigid laryngoscopy was graded and the ability of experienced anesthesia personnel to ventilate via a mask was determined. Poor intubating conditions (laryngoscopy Grade IV) and inability to achieve adequate mask ventilation were identified in 107 (1%) and 8 (0.07%) cases, respectively. Logistic regression identified all seven criteria as independent predictors of difficulty with laryngoscopic visualization. A composite airway risk index (derived from nominalized odds ratios calculated from the multivariate model) as well a simplified (0 = low, 1 = medium, 2 = high) risk weighting exhibited higher positive predictive value for laryngoscopy Grade IV at scores with similar sensitivity to Mallampati class III, as well as higher sensitivity at scores with similar positive predictive value. Compared to Mallampati class I fewer false-negative predictions were observed at a risk index value of 0. We conclude that improved risk stratification for difficulty with visualization during rigid laryngoscopy (Grade IV) can be obtained by use of a simplified preoperative multivariate airway risk index, with better accuracy compared to oropharyngeal (Mallampati) classification at both low- and high-risk levels.

Imaging of the larynx

CT and MR imaging are the main modalities for examination of laryngeal pathology. In general, MR imaging seems to be the optimal method of examination in cooperative patients, especially for evaluation of their larynx prior to an attempted partial laryngectomy. CT is recommended in patients who may have rapid breathing or coughing or if MR imaging is contraindicated. The choice between the two modalities is also determined by the experience of the radiologist with these modalities. Both techniques are comparable in delineating site and extent of pathology in fat and muscular tissue. MR imaging is more sensitive than CT in detecting pathologic involvement of the cartilages. CT and MR imaging are helpful in characterization of cartilaginous tumors and benign lesions, such as laryngoceles and cysts. CT is used to assess the integrity of the laryngeal skeleton in patients who suffered from trauma, that is, for identification of occult fractures, dislocations of cartilages, or confirmation of suspected laryngeal injuries.

Force and torque vary between laryngoscopists and laryngoscope blades

Several studies have examined the effects of patient characteristics on force of laryngoscopy, but little attention has been paid to the importance of technique and equipment. This study investigated whether force, torque, head extension, and view varied significantly between laryngoscopists and compared force and torque using Macintosh 3 and Miller 2 blades. The study population consisted of ASA grade I and II patients requiring general anesthesia and endotracheal intubation for elective surgery. Force, torque, head extension, and laryngeal view were highly reproducible when laryngoscopy was repeated by the same individual, Force and torque showed great variation between laryngoscopies performed by different anesthetists, For example, peak force varied over a range of 56 newtons among patients, but could also vary as much as 30 newtons between different anesthetists repeating laryngoscopy in the same patient. Force and head extension were 30% less with Miller laryngoscope compared to the Macintosh. Thus, laryngoscopic force and torque depend on technique and equipment. Further studies of force and torque may lead to improved techniques. The force-measuring laryngoscope could be a useful tool in teaching laryngoscopy.

[The echographic anatomy of the larynx and the perilaryngeal structures]

The normal laryngeal and perilaryngeal structures (neither nodal nor vascular) of 120 healthy and informed volunteers and of 46 patients with extralaryngeal neck conditions were studied with ultrasonography (US). The study was performed with a high-frequency linear probe on the transverse and sagittal planes; the patients were examined supine, with neck hyperextension, during quiet breathing, in inspiratory and expiratory breath-holding, during Valsalva maneuver or phonation. Axial scans clearly depict, in cranio-caudal direction, the base of the tongue, the hyoid and adjacent muscular structures. At the laryngeal vestibule epiglottis is always clearly demonstrated as a thin hypoechoic curvilinear rim and the pre-epiglottic space as a fat-filled and markedly echogenic structure. Pyriform sinuses are more difficult to study with US and should therefore be always distended by air during Valsalva because no suitable US contrast agent is available for their exploration yet. The ossification of thyroid laminae prevents or hinders the exploration of endolaryngeal structures because of consequent posterior acoustic shadow. In case of partial ossification or cartilaginous thyroid laminae, paraglottic spaces are easily demonstrated with US, as well as the false cords and, partially, arytenoids and posterior laryngeal wall muscles. The muscular structure of the true cords, their mobility in the M-mode and, in half of the cases, the thin vocal plicae joining anteriorly in the anterior commissure, are easily depicted with US. To conclude, US permits to demonstrate normal laryngeal anatomy by a quick and harmless examination in several breathing and phonation phases, which is an essential premise to the correct interpretation of abnormal US findings.

Force, torque, and stress relaxation with direct laryngoscopy

The anesthetist exerts axial force on the laryngoscope handle to expose the glottis. The anesthetist must also apply a perpendicular force to balance the torque on the laryngoscope. Several studies have measured axial force during direct laryngoscopy, but none has measured torque. This study used a newly designed laryngoscope handle to measure force and torque simultaneously during direct laryngoscopy of ASA grade I and II patients requiring general anesthesia and endotracheal intubation for elective surgery. In 58 patients, peak force averaged 38 +/- 2 newtons. Peak torque averaged 4 +/- 0.2 newton-meters, and the perpendicular force was estimated as 40 +/- 2 newtons. The peak torque that can be balanced by the wrist is approximately 6 newton-meters, suggesting that torque may be a limiting factor for laryngoscopy in some situations. Peak force and torque demonstrated stress relaxation, a viscous property of biologic tissues. Force and torque decreased monoexponentially to approximately 70% of peak values with a half-time of 4 +/- 0.3 s. The phenomenon occurred in spite of administration of muscle relaxants, and was probably due to stress relaxation of pharyngeal tissues that are passively stretched during laryngoscopy.

The periepiglottic space: topographic relations and histological organisation

Important aspects of histological organisation and topographic relations of the pre-epiglottic space are not fully understood. This region was therefore reinvestigated in plastinated serial sections of 19 human adult specimens. The cranial part of the pre-epiglottic space is homogenously filled with adipose tissue and extends around the epiglottis in a horseshoe fashion. Therefore, the term periepiglottic space (PES) is a more accurate description of this region. The cranial border of the PES is constituted by the hyoepiglottic membrane, which extends between the epiglottis and the tongue, and the hyoepiglottic ligament. The ligament consists of a cranial fibre layer anchored within the lingual muscles, and a caudal layer attached to the hyoid bone. Anterior to the lingual surface of the epiglottis, both fibre layers become apposed to form a dense collagenous mass, which may stabilise the epiglottis during deglutition. Contractions of the infrahyoid muscles will be transmitted to the thyrohyoid membrane anterior to the PES by numerous collagenous septa which originate from the membrane and radiate into the muscles. In contrast, the pre-epiglottic adipose tissue is not connected to the thyrohyoid membrane. The caudal part of the PES is subdivided by two paramedian sagittal collagenous septa. They include a medial compartment bordered by the epiglottis posteriorly and the thyroepiglottic ligament inferiorly. The two lateral subdivisions of the PES extend between the glands of the vestibular folds and towards the aryepiglottic folds, but a distinct confining collagenous layer is absent there. Posterolaterally, the PES is separated from the paraglottic space by the thyroarytenoid muscle and by a cranial extension of the fibrous sheet of the muscle. This collagenous tissue is often split into several layers and displays gaps which may facilitate the spread of malignancies.

Laryngeal neurophysiology and its clinical uses

A fact well known to all otolaryngologists, but which occasionally bears repeating, is that the larynx is not just an organ of communication. The larynx sits at the crossroads of the pathways of air and food intake, and serves the vital function of keeping ingested food and water from entering the lungs. Another obvious consideration, however, is that if the larynx were not there and if the breathing and alimentary passages were totally separate (as after surgical laryngectomy), then there would be no need for the larynx other than to speak. Thus, in terms of survival of the organism, laryngectomy can be considered a viable treatment option any time laryngeal dysfunction compromises health. The problem with this line of reasoning, of course, is that speech, in humanistic terms, is a very compelling need. Someone who communicates in any mode other than that of normal speech is at a distinct disadvantage in almost any culture. Therefore, at its essence, the subspecialty of laryngology has as its central mission the preservation or restoration of normal voice and speech by the natural mechanism. In accomplishing this, it is necessary to understand how the larynx functions as an integral component of the systems for speech, breathing, and swallowing. The intent of this article is to outline essential features of laryngeal function, to describe how function is impaired by diseases, and to offer examples of the clinical significance of this information.

[The voice of the child, morphological evolution of the larynx and its acoustic consequences]

From a review of the literature, the authors analyze the role of laryngeal modifications in the evolution of a child's voice. The modifications found are topographic (laryngeal descent in the neck), morphologic (increase in volume modification of laryngeal shape), and histologic (lamina propria differentiation), each responsible for acoustic modifications. The chronological evolution of the voice integrates these modifications in a global context of development, where the central nervous system is of primary importance.

The attachments of the conus elasticus to the laryngeal skeleton: physiologic and clinical implications

The attachments of the inferior and dorsal extensions of the lateral parts of the conus elasticus (CE) are not fully understood. A re-investigation was done in plastinated serial sections of 20 adult human larynges. The CE consists of a coherent sheet of connective tissue fibers dividing into two layers toward the inferior anchorage to the cricoid arch, and the posterior anchorage to the cricoid lamina. Caudally, the medial fiber layer is continuous with the submucous fibroelastic membrane of the trachea and is not connected to the cricoid cartilage. The lateral caudal fiber layer is attached to the superior rim of the cricoid arch. Dorsally, both layers of the CE are fixed to the cricoid lamina, the lateral sheet to the lateral edge of the cartilage, the medial sheet to its anterior perichondrium near the midline. Towards the cricoarytenoid joint, the dorsal extension of the CE divides into a caudal and a cranial sheet including a fold of adipose tissue at the base of the arytenoid cartilage. The cranial layer extends towards the vocal process, the caudal layer radiates into the joint capsule and may therefore influence the complicated joint mechanics. The firm attachments of the CE to the cricoid cartilage probably counteract deformations of the CE during phonation. An insufficient fixation of the CE may contribute to an obstruction of the airways causing sleep apnea.

The cricoarytenoid ligament: its morphology and possible implications for vocal cord movements

The cricoarytenoid ligament was studied in sections of ten plastinated adult human larynges. The collagenous fibres forming the ligament originate from a small area at the upper rim of the cricoid lamina and from the adjacent dorsal cricoid perichondrium. The fibres strengthen the dorsal and medial part of the capsule of the cricoarytenoid joint. They are arranged in several layers separated by adipose tissue. The most medial layer of the collagenous fibres is attached to the medial aspect of the vocal process, whereas the vocal cord is anchored more laterally. Contrary to the descriptions in the literature, no fibres of the cricoarytenoid ligament join the vocal cord. Especially, the medial part of the ligament is important for controlling abduction and abduction of the vocal cords. Voice disturbance may result from structural asymmetry of the cricoarytenoid ligament.