Membranous and cartilaginous vocal fold adduction in singing

While vocal fold adduction is an important parameter in speech, relatively little has been known on the adjustment of the vocal fold adduction in singing. This study investigates the possibility of separate adjustments of cartilaginous and membranous vocal fold adduction in singing. Six female and seven male subjects, singers and non-singers, were asked to imitate an instructor in producing four phonation types: "aBducted falsetto" (FaB), "aDducted falsetto" (FaD), "aBducted Chest" (CaB), and "aDducted Chest" (CaD). The phonations were evaluated using videostroboscopy, videokymography (VKG), electroglottography (EGG), and audio recordings. All the subjects showed less posterior (cartilaginous) vocal fold adduction in phonation types FaB and CaB than in FaD and CaD, and less membranous vocal fold adduction (smaller closed quotient) in FaB and FaD than in CaB and CaD. The findings indicate that the exercises enabled the singers to separately manipulate (a) cartilaginous adduction and (b) membranous medialization of the glottis though vocal fold bulging. Membranous adduction (monitored via videokymographic closed quotient) was influenced by both membranous medialization and cartilaginous adduction. Individual control over these types of vocal fold adjustments allows singers to create different vocal timbres.

Implementation of a virtual laryngoscope system using efficient reconstruction algorithms

BACKGROUND

Conventional fiberoptic laryngoscope may cause discomfort to the patient and in some cases it can lead to side effects that include perforation, infection and hemorrhage. Virtual laryngoscopy (VL) can overcome this problem and further it may lower the risk of operation failures. Very few virtual endoscope (VE) based investigations of the larynx have been described in the literature.

MATERIAL/METHODS

CT data sets from a healthy subject were used for the VL studies. An algorithm of preprocessing and region-growing for 3-D image segmentation is developed. An octree based approach is applied in our VL system which facilitates a rapid construction of iso-surfaces. Some locating techniques are used for fast rendering and navigation (fly-through).

RESULTS

Our VL visualization system provides for real time and efficient 'fly-through' navigation. The virtual camera can be arranged so that it moves along the airway in either direction. Snap shots were taken during fly-throughs. The system can automatically adjust the direction of the virtual camera and prevent collisions of the camera and the wall of the airway.

CONCLUSIONS

A virtual laryngoscope (VL) system using OpenGL (Open Graphics Library) platform for interactive rendering and 3D visualization of the laryngeal framework and upper airway is established. OpenGL is supported on major operating systems and works with every major windowing system. The VL system runs on regular PC workstations and was successfully tested and evaluated using CT data from a normal subject.

[The tensegrity concept applied to the laryngeal biodynamics]

The knowledge of spaces and sliding ways of the forehead part of the neck must be accomplished, however the microscopic observation of these sliding ways shows in fact a real concrete material continuity, through the existence of a binding tissue between the sliding structures. This tissue is shaped in a web form system of multimicrovacuolar collagenic fibers. It respects the functional unit, while saving the relative independance of moving between the different structures concerned. The architectural features of any living tissue may be reported to a tensegrity system. The word of tensegrity is a portmanteau of tensional-integrity, as proposed by the american architect Richard Buckmister Fuller. Following tensegrity the laryngeal biodynamic behaviour is based on two sets of tensions and compressions applied on itself. The laryngeal system is therefore in a constant balance of tissular tensions. The multimicrovacuolar system has a main place. This new point of view may be applied to the laryngeal dysfunctions.

The Gross Anatomy of Larynx, Trachae and Syrinx in the Long-Legged Buzzard (Buteo rufinus)

Five long-legged buzzards (Buteo rufinus), weighing 475-570 g, were used in this study. It was determined that long-legged buzzards' larynx is composed of three different cartilages. Among these cartilages, the cricoid and procricoid cartilages were single and the arytenoid cartilage was double. The partially ossified corpus and ala of the cricoid cartilage were connected with cartilaginous plate. Trachea was formed up of complete cartilage circles. The tracheal cartilages were notched in dorsal and ventral directions and a number of the tracheal cartilages inter-mingling one another were between 89-96. Syrinx, which was covered with the inter-clavicular air sac, was in contact with basis cordis. It was observed that there is tracheobronchial type syrinx in long-legged buzzard and this syrinx is formed by two different cartilage groups named as the cartt. tracheosyringeales and cartt. bronchosyringeales. The first cartilage rings of the cartt. tracheosyringeales formed the tympanum. The tympanum, cartt. tracheosyringeales and cartt. bronchosyringeales were created of three, two or three and four cartilage rings, respectively. Membrana tympaniformis lateralis and medialis, two pairs of thin membranes constituting voice formation, also determined in long-legged buzzard. Membrana tympaniformis lateralis was observed to be very short between the first and second cartilage rings of cartt. bronchosyringeales. Although the instrictic syringeal muscles were not present in long-legged buzzard, the sternotracheal and tracheolateral muscles, expressed as extrinsic syringeal muscles, were evident. In this study, which is expected to give contribution to veterinary anatomy literature, the similarities and differences in larynx, trachea and syrinx of long-legged buzzard with other bird species were exposed.

[Is there a consensus in the division of the vocal folds in thirds?]

INTRODUCTION

In clinical routine we have noticed a disagreement of ENT-specialists and phoniatricians in the division of the vocal folds in thirds. To show if there is consensus in this field by the german phoniatricians this study was done.

MATERIAL AND METHODS

In two parts of a study, a pilot study and a follow up study, we sent twelve different images of the larynx to all german phoniatricians. In six of these images the physicians should set the marks of the ventral and dorsal limitation of the second third of the vocal folds. In six different images a mark should be related to the particular third of the vocal folds. The phoniatricians were asked to assess how certain they were in their valuation. They were asked either, how long they have been working as a physician and how long they have been specialized as a phoniatrician and as an ENT-surgeon. In the follow up study the phoniatricians were requested to first divide up the thirds in a way that the dorsal third corresponds to the cartilaginous part of the vocal folds (scheme 1) and second divide up the thirds in a way that all three thirds correspond to the ligamental part of the vocal folds. DISCUSSION AND FINDINGS: In the pilot study, when no instructions for the division of the thirds were given, the data differed much more than in the follow up study, when the physicians were told to use scheme 1 and scheme 2. That was because some phoniatricians divided up just the ligamental part and others the ligamental plus the cartilaginous part of the vocal folds in thirds. The more the physicians could overlook the membraneous part of the vocal folds the more certain they were in their assessment.

CONCLUSION

The assessment of the division of the vocal folds in thirds is more homogeneous when the phoniatricians were requested to divide up the thirds in a way that the dorsal third corresponds to the cartilaginous part of the vocal folds (scheme 1). Therefore we suggest that this way of division should be used further on.

Normal age-related signal change in the laryngeal cartilages

MRI may be used for detecting cartilage invasion in patients with laryngeal carcinoma. However, the normal laryngeal ossification pattern has not been studied. Our purpose was to examine the normal age-related signal patterns in the cricoid, thyroid and arytenoid cartilages on T1-weighted images. Signal in the cartilages was assessed by two radiologists in a blinded fashion using three-point scales for intensity and symmetry. Statistical analysis consisted of logistic and monotonic regression. There was excellent interobserver agreement (>85%) for all categories. The cartilages predominantly ossify symmetrically and the extent of high signal from all three increases with age. The latter may help in detection of cartilage invasion by tumor in older patients. Normal symmetry may be helpful when comparing sides for tumor invasion.

[Visualization and thin sectional anatomy of the laryngeal cartilages]

OBJECTIVE

To establish digitized visible model of the laryngeal cartilages of the visible human, providing morphological data for image diagnosis and laryngectomy.

METHODS

Cross-sectional images of fresh tissues from the Chinese visible human data set were reviewed, and the laryngeal cartilages structures data were used, the data was on a section-by-section basis. Three-dimensional computer reconstructions of the laryngeal cartilages were generated from these data by surface rendering on a SGI workstation.

RESULTS

The digital images from the visible human offer unique insights into the complex anatomy and ossification of the laryngeal cartilages, the quality of the computerized 3D-reconstructed images was distinct and perfect.

CONCLUSIONS

The visible human data set can provide complete and accurate data The digitized model of the laryngeal cartilages offer unique insights into the laryngeal anatomy, could be used for resident education, rehearsal of an unfamiliar surgery and for developing a new surgical approach.

Age estimation using radiographic analysis of laryngeal cartilage

The laryngeal cartilages undergo age changes, including mineralization and ossification. Keen and Wainwright defined, in male and female subjects, recognizable stages of radiopacity of the thyroid, cricoid, and arytenoid cartilages. The present study analyzed quantitatively the degree of laryngeal radiopacity to determine whether radiography of the larynx can be used routinely in forensic pathology to estimate age at death. In each of 82 subjects, the larynx was removed during forensic autopsy and subjected to radiography in an anteroposterior orientation. Each radiograph was independently scored by two observers. For each case, the degree of laryngeal radiopacity was evaluated according to the classification of Keen and Wainwright. There was a positive correlation between the total score of laryngeal radiopacity and age (correlation coefficient = 0.74). It was concluded that this method is simple, fast, and nondestructive and has a good reproducibility between observers. Because there was a wide interindividual variability in the same age class, this method must be associated with more accurate methods.

Medical THz imaging: an investigation of histo-pathological samples

We present a THz investigation of histo-pathological samples including the larynx of a pig and a human liver with metastasis. Our measurements show that different types of tissue can be clearly distinguished in THz transmission images, either within a single image or by a comparison of images obtained for different frequency windows. This leads to the problem that images obtained for different frequencies inherently have a different spatial resolution. An image obtained from two such images by a simple mathematical operation may contain artefacts. We discuss measures to deal with this problem. Furthermore, we investigate the possibility of improving the spatial resolution of THz images. Finally, we present a cw THz imaging system based on a photomixer and an external cavity semiconductor laser that allows for simultaneous two-mode operation. The cw system is less expensive and more compact than conventional time-domain imaging systems.

Developing an anatomical model of the human laryngeal cartilages from magnetic resonance imaging

The purpose of this work was to construct a three-dimensional anatomical framework of the cartilages of the human larynx. The framework included representative surface models of the four laryngeal cartilages and estimated attachment points for the intrinsic laryngeal muscles. High-resolution magnetic resonance imaging (MRI) was used to scan one female and four male human cadaveric larynges. The cartilages were segmented manually from the MRI volume for analysis. Two of these larynges were subsequently dissected and the landmark distances on the cartilages measured for comparison with the MRI measures and previous studies. The MRI measures were 8% smaller than the anatomical measures and 12% smaller than data reported in the literature. A laryngeal coordinate system was defined using the plane of symmetry of the cricoid cartilage. Measures of cricoid cartilage symmetry had less than 3% difference between the two sides for a series of measures. An algorithm for registering larynges that minimized the root-mean-square distance between the surface of a reference cricoid cartilage and the surfaces of nonisotropically scaled candidate cricoid cartilages was evaluated. This study provided an anatomical framework for registering different larynges to the same coordinate space.

Functional definitions of vocal fold geometry for laryngeal biomechanical modeling

Precise geometric data on vocal fold dimensions are necessary for defining the vocal fold boundaries with respect to the laryngeal framework in physiological and biomechanical models of the larynx (eg, finite-element models). In the mid-membranous coronal section, vocal fold depth can be defined as the horizontal distance from the vocal fold medial surface to the thyroid cartilage, whereas vocal fold thickness can be defined as the vertical distance from the inferior border of the thyroarytenoid muscle to the vocal fold superior surface. Traditionally, such geometric data have been obtained from measurements made on histologic tissue sections. Unfortunately, it is very difficult to obtain reliable data by this method, unless the effects of sample preparation on vocal fold geometry are quantified. Significant tissue deformations are often induced by histologic processes such as fixation and dehydration, sometimes producing shrinkages as large as 30%. In this study, reliable geometric data of the canine vocal fold were obtained by the alternative method of quick-freezing for sample preparation, using liquid nitrogen. Coronal sections of quick-frozen larynges were thawed gradually in saline solution. Images of the mid-membranous coronal sections at various thawing stages were captured by a digital camera. Measurements of operationally defined vocal fold dimensions (depth and thickness) useful for biomechanical modeling were made with a graphics software package. The results showed that geometric changes of the vocal fold induced by freezing are likely reversed by thawing, such that the measurements made on thawed larynges are reliable approximations of the actual vocal fold dimensions.

Geometric characterization of the laryngeal cartilage framework for the purpose of biomechanical modeling

Some new anatomic data on the laryngeal cartilage framework have been obtained for the biomechanical modeling of the larynx. This study attempted to define and measure some biomechanically important morphometric features of the laryngeal framework, including both the human and the canine laryngeal frameworks, because the canine larynx has been frequently used as an animal model in gross morphology and in physiological experiments. The larynges of 9 men, 7 women, and 9 dogs were harvested and dissected after death. Linear and angular geometric measurements on the thyroid cartilage, the cricoid cartilage, and the arytenoid cartilage were made with a digital caliper and a protractor, respectively. The results are useful for constructing quantitative biomechanical models of vocal fold vibration and posturing (abduction and adduction), eg, continuum mechanical models and finite-element models of the vocal folds.

Functional anatomy and physiology of the upper esophageal sphincter

Upper esophageal sphincter (UES) refers to the high-pressure zone located in between the pharynx and the cervical esophagus. The physiological role of this sphincter is to protect against reflux of food into the airways as well as prevent entry of air into the digestive tract. UES is a musculocartilaginous structure with its anterior wall being formed by the full extent of the posterior surface of the cricoid cartilage and arytenoid and interarytenoid muscles in the upper part. Posteriorly and laterally the cricopharyngeus (CP) muscle is a definitive component of the UES. CP has many unique characteristics: it is tonically active, has a high degree of elasticity, does not develop maximal tension at basal length, and is composed of a mixture of slow- and fast-twitch fibers, with the former predominating. These features enable the cricopharyngeus to maintain a resting tone and yet be able to stretch open by distracting forces, such as a swallowed bolus and hyoid and laryngeal excursion. CP, however, constitutes only the lower one third of the entire high-pressure zone. The thyropharyngeus (TP) muscle accounts for the remaining upper two thirds of the UES. The UES pressure is not entirely the result of myogenic activity, as a component of the pressure is the result of passive elasticity of the tissues. The opening of the UES involves relaxation of CP and TP muscles and forward movement of the larynx by the contraction of hyoid muscles. The UES function is controlled by a variety of reflexes that involve afferent inputs to the motorneurons innervating the sphincter. These physiological reflexes elicit either contraction or opening of the UES. Inability of the sphincter to open leads to difficulty in swallowing. Opening of the sphincter without associated CP relaxation leads to the clinical syndrome of cricopharyngeal bar.

Morphometric measurements of the cartilaginous larynx: An anatomic correlate of laryngeal surgery

BACKGROUND

The increasing application of sophisticated methods of laryngeal framework surgery requires a profound knowledge of the size and proportions of the human larynx and its cartilaginous components. Only inadequate data regarding this subject have so far been accessible. The aim of this study was to collect exact and reliable morphometric data of the human laryngeal framework. Materials and Methods Larynges from 98 corpses (52 male, 46 female) were removed during autopsy 4-64 hours postmortem and processed without delay or fixation. Following a standard routine for preparation, 28 parameters were measured on thyroid cartilage, cricoid cartilage, arytenoid cartilage, epiglottis, and the larynx as a whole organ. None of the patients had histories or visible signs of laryngeal disease. Anatomical preparations were performed with customary surgical tools and morphometric measurements then carried out with a pair of compasses and a caliper rule.

RESULTS

A total of 5,100 measurements was performed on 98 larynges. These included, aside from evaluation of the whole organ, identification of the internal and external diameters of the cricoid cartilage, height and length of the thyroid alae in different planes, angle of thyroid alae, height of arytenoid cartilage, width and length of epiglottic cartilage, and position of the anterior commissure related to the thyroid cartilage. The results provide a full scale of data determining the size and extent not only of the cartilaginous components, but of the laryngeal framework as a whole. Mean values, standard deviations, and sample sizes are given for every parameter separately for both sexes.

CONCLUSION

This study provides a comprehensive and detailed description of the dimensions of the adult human larynx.

[Histological study of the tracheal adventitia, perichondrium and annular ligament]

The trachea begins at the lower border of the cricoid cartilage and passes down to bifurcate into the left and right mainstem bronchi. The presence of tracheal invasion is crucial factor influencing the prognosis for patients with cancers of the thyroid gland, hypopharynx, esophagus, etc. In order to understand the manner of invasion of the above tumors, precise knowledge of the normal tracheal structure is indispensable. This study was undertaken to clarify the normal microscopic structure of the trachea. Five normal tracheal specimens obtained at surgery were examined histologically and immunohistochemically. The loose connective tissue around the trachea, known as adventitia, was divided into a loose outer and a dense inner layer by hematoxylin and eosin (HE) staining. This two-layer pattern was clearly seen near the annular ligament but was obscured away from it. The connective tissue of the inner layer ran obliquely to joint the connective tissue of the annular ligament and ended in the submucosal layer. This arrangement of connective fibers seems to play a role in allowing the trachea to stretch and bend. Tracheal cartilage is covered with a dense fibrous membrane known as the perichoundrium. Between the superficial fibrous membrane and mature cartilage cells lies zone of immature cartilage made up of oval or spindle cells, and the inclusion of this zone in the perichondrium has long been a subject of controversy. In our study, the zone was homogeneously stained red by the elastica van Gieson's stain and was clearly distinguished from other structures. Immunohistochemical staining revealed a wide distribution of type I and type III collagen on the fibrous membrane and the zone of immature cartilage cells, while mature cartilage cells did not show such collagen. Based on these findings, we conclude that the zone of immature cartilage cells belongs to the periochondrium, which thus contains two layers, an outer fibrous layer and an inner transitional layer of immature cartilage cells. Our conclusions are as follows: 1. Tracheal adventitia is divided into two layers, an outer loose and an inner dense fibrous layer. 2. Tracheal perichondrium also consists of two layers, an outer fibrous layer and an inner transitional layer. 3. The fibrous bundle originating from the adventitia joins the connective tissue of the annular ligament, probably in order to allow the trachea to stretch and bend.

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 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.

Morphological modeling via isosurfacing: the laryngeal skeleton of gekkonid lizards as a test case

A novel technique for modeling microscopic anatomical structures in three dimensions was developed as part of a survey of gekkonid laryngeal skeletal morphology (Reptilia: Gekkonidae). Excised larynges were transversely sectioned at 10 microns and stained using standard procedures. With a projection microscope, outline drawings of the sectioned laryngeal cartilages were made at regular intervals, depending on the rate and degree of structural change observed while sampling. The drawing set was digitized with a flatbed scanner, and aligned using 'NIH Image' for Macintosh computers. Physical connectivity between successive outlines was provided by inserting one or more artificial slices between those that had been digitized, and draping a skin of rendered contours over all of the interstitial spaces present in the template. The Application Visualization System, a general purpose visualization package for UNIX-based computer systems, was used to visualize and render the resulting 'isosurfaces', which appear as solid three-dimensional objects and can be viewed from any perspective. Since isosurfaced reconstructions can be based on as little as 20% of the cross-sections available, this procedure has the potential to be a valuable research tool for future morphological work at the microscopic level.

[Post-radiation necrosis of the cricoid cartilage: an uncommon case]

Radiation therapy is considered as the treatment of choice for early stage laryngeal cancer. However, a few patients, after several years, develop severe life threatening complications, like edema or chondronecrosis. The clinical examination or endoscopy follow up may be difficult. CT and MR imaging can show the exact diagnosis depicting exquisitely the anatomy of the larynx. But at the beginning, the abnormalities are radiographically subtle and their diagnosis may be difficult because of artefacts due to patient dyspnea and mucous secretions. The main suggestive imaging features for suspecting a chondronecrosis seem to be the lost of normal signal hyperintensity on T1 MR imaging or a focal lack of cortical bone on CT scans, just adjacent to a focal swelling of the pharyngo-larynx mucosa. The barium pharyngography remains the best imaging diagnosis procedure for depicting associated abnormal communication between the digestive tract and the adjacent spaces or the cartilages of the larynx. Therefore, when the diagnosis is delayed, only salvage total laryngectomy can stop the infectious process. We report one case of a cricoid cartilage chondronecrosis eleven years after radiation therapy for laryngeal cancer.

[Superior laryngeal nerve in thyroid surgery]

In this paper, the authors discuss the risks of lesions to the external branch of the superior laryngeal nerve during surgical procedures on the thyroid gland. These lesions result in significant functional impairment consisting on the patients' impossibility of emitting high-pitched sounds, an easy tiredness in vocalizing, huskiness, or a combination of these symptoms. Recently, in effect, with the increasing use pre and postoperatively of newer diagnostic tools such as electromyography (EMG) of the cricothyroid muscle, a fairly high incidence of permanent or temporary, including single or bilateral lesions to this nerve was demonstrated. The necessity of using appropriate surgical techniques with the objective of avoiding or markedly reducing the incidence of lesions to the superior laryngeal nerve is discussed in detail by the authors.

Dimensions of the laryngeal framework in adults

The increasing application of sophisticated electrophysiological, radiological and surgical methods to the diagnosis and treatment of laryngeal disorders requires a profound knowledge of the size and proportions of the human larynx and it's cartilaginous components. Only inadequate data regarding this subject have so far been accessible. The larynges of 53 patients (28 male and 25 female, age 25-88 years, in the means 59 years) were removed during routine autopsy 12-48 h post mortem and immediately submitted to morphometric investigation. None of the patients had histories or visible signs of laryngeal disease. Anatomical preparations were performed with customary surgical tools and morphometric measurements then carried out with a pair of compasses and a calliper rule. A total of 95 measurements were performed on each larynx. These included, aside from evaluation of the whole organ, identification of the internal and external diameters of the cricoid cartilage, height and length of the thyroid alae in different planes, angle of thyroid laminae, height of arytenoid cartilage, width and length of epiglottic cartilage, and internal and external diameter of first tracheal ring. The results obtained provide a full scale of data determining the size and extent not only of it's cartilaginous components, but of the laryngeal framework as a whole. The knowledge of these data may contribute to a precise positioning of electrodes in laryngeal electromyography, to the planning of laryngeal framework surgery, and to the analysis of CT- and MRI-scans of the larynx.

Ligaments of the larynx and the adjacent pharynx and esophagus

Two ligament systems of the larynx are demonstrated by dissection. The suspensory ligament of the esophagus is attached to the posterior aspect of the cricoid cartilage and is also a part of the fascial sheath which is common to the hyoid, thyroid, and cricoid. The ligaments at the inner margins of the vocal, ventricular, and aryepiglottic folds are distinctive in site and, inferentially, in function. The aryepiglottic ligaments join at the incisura between the arytenoid cartilages and are continued as the corniculopharyngeal ligament which splays into the flexible tissues in the anterior wall of the hypopharynx, posterior to the suspensory ligament of the esophagus. These ligament systems are involved in two different actions in swallow. The gross superior and anterior motions of the larynx are transmitted to the esophagus by the suspensory ligament, so that the esophagus is elevated in relation to the bolus and is also opened. These esophageal displacements resemble, in effect, the swallow displacements of the pharyngoesophageal segment and of the constrictor wall of the hypopharynx. The marginal ligaments of the laryngeal folds help to implement the constriction and closure of the larynx during swallow. By anatomical inference, the corniculopharyngeal ligament effects vertical traction within the flexible tissues of the anterior wall of the hypopharynx.

[Spin-echo anatomy of the larynx in MRI at 1.5 T]

The larynges of 8 healthy and informed volunteers were studied with a superconductive MR unit at 1.5 T together with those of 10 patients with extra-laryngeal pathologic conditions. The study was performed with round surface coils (5'') and with delicated sellar coils in the anterior neck. Slices were 5 mm thick, and acquired on the coronal, axial, and sagittal planes, with T1-weighting; axial scans were repeated in the same locations with double echoes, with proton-density and T2-weighting. Five patients underwent additional scans after Gd-DTPA. The larynx of a semi-frozen cadaver was examined with sellar surface coils, on similar scanning planes and with similar pulse sequences to those described above; the larynx was removed, investigated with mammographic technique, and subsequently analyzed with thin CT slices and a high-resolution reconstruction algorithm for the study of laryngeal cartilage. Axial anatomical sections were then compared with MR and CT scans, and the anatomical structures were recognized on the triplanar MR scans of a volunteer's larynx. Besides MR anatomy of supporting laryngeal structures, the authors describe in detail the muscles, plicae, spaces and cavities which can be identified on the various planes, together with the changes in signal after Gd-DTPA.

Pre-therapeutic evaluation of laryngeal carcinomas using computed tomography and magnetic resonance imaging

A prospective and comparative computed tomography (CT)/magnetic resonance imaging (MRI) study on 90 patients with endoscopically examined and histologically proven laryngeal malignancy is presented. Post-operative pathological and intra-radiological (CT vs. MRI) correlations are established. We conclude that MRI is the method of choice for staging laryngeal malignancies.

A metrical study of the laryngeal skeleton in adult Nigerians

Laryngeal cartilages were studied in 40 dissection room specimens of adult age groups ranging from 17 to 50 years in both the sexes. Various dimensions of the laryngeal skeleton were measured and statistical analysis of the data for male and female were evaluated separately. Conspicuous and highly significant differences of the dimensions between male and female laryngeal cartilages were observed. The incidence of the cuneiform cartilage and cartilago triticea was greater in the female than in the male.

Distribution of elastic cartilage in the arytenoids and its physiologic significance

An investigation of the distribution of the elastic cartilage in the arytenoids was performed on excised human adult and newborn larynges. The distribution of elastic cartilage in the arytenoids was investigated histologically in two serial sections: horizontal and coronal. The behavior of the elastic cartilage portion of the arytenoids was investigated histologically under the conditions of adduction and abduction. The results are summarized as follows. 1) Elastic cartilage is found not only at the tip of the vocal process but at the superior portion of the arytenoid cartilage from the vocal process to the apex. 2) This phenomenon is observed at birth. 3) The vocal process bends at the elastic cartilage portion during adduction and abduction. The sides of the arytenoids come into contact mainly at the elastic cartilage portion. 4) Elastic cartilage appears to play an important role in the physiologic functioning of the arytenoid.

MR imaging of the larynx at 1.5 T

The normal magnetic resonance (MR) anatomy of the larynx at high field strength (1.5 T) was studied in 2 normal excised larynges and 62 subjects without laryngopharyngeal disease. The two normal excised larynges were imaged using a 1.5 T MR scanner with a 3 in diameter circular surface coil and a GE 9800 CT scanner. The larynges were sectioned transversely and the MR and CT images compared to gross and histologic sections. Unossified hyaline cartilage was intermediate in signal intensity on T1-weighted and proton density images and low in intensity on T2-weighted images. The signal intensity from ossified cartilage was determined by the amount of fatty marrow and was high in intensity on T1-weighted and proton density images and low to intermediate in intensity on T2-weighted images. A chemical shift artifact from high intensity fatty marrow obscured the calcified or ossified cortex of the major laryngeal cartilages along the frequency encoding axis. The epiglottic cartilage demonstrated an intermediate signal intensity on T1-weighted images and higher intensity on proton density and T2-weighted images. The intralaryngeal muscles were well demonstrated as low intensity structures. The conus elasticus and the vocal ligaments were not recognized as distinct structures. However, the quadrangular membrane and a previously undescribed membrane separating the preepiglottic and paralaryngeal spaces were shown on MR as low intensity linear structures. In the 62 subjects, MR at 1.5 T proved excellent for demonstrating the anatomical details of the major laryngeal cartilages, extra- and intralaryngeal muscles, ligaments, and soft tissues including the vocal cords, false vocal cords, laryngeal ventricles, aryepiglottic folds, preepiglottic space, and paralaryngeal spaces. Visibility and intensity of muscles, ligaments, and soft tissues did not depend on age or sex. The intensity pattern of the thyroid and cricoid cartilages demonstrated wide variations in the same sex and age groups, depending on the degree of ossification. However, they did show more high intensity foci in older men than in younger women. Magnetic resonance showed better contrast resolution and finer detail than CT scans in the same subjects. Magnetic resonance imaging at 1.5 T, with either a saddle-shaped neck surface coil or a 3 in diameter circular surface coil, provides high contrast and high spatial resolution images and could be useful for the diagnosis of lesions of the larynx.(ABSTRACT TRUNCATED AT 400 WORDS)

The foci of the red bone marrow observed in the laryngeal cartilages of the Suncus murinus

In the Suncus murinus, the thyroid, the cricoid and the arytenoid cartilages were in part ossified. The foci of the red bone marrow, termed as the "marrow foci", were observed in the ossified portion of the cartilages. The marrow foci were filled with mature and immature blood cells. It is suggested that the marrow foci take part in active hematopoiesis in the Suncus. Further, a canal which connected the marrow cavity and the outside of the cartilage was occasionally seen. It seems that the canal corresponds to the nutrient canal.

Anatomic foramina in the thyroid cartilage: incidence and implications for the spread of laryngeal cancer

Anatomic openings in the posterosuperior portion of the thyroid lamina of the larynx were first described in the 19th century. In the present study of 121 coronally sectioned larynges, such openings were found in 47 (39%), appearing bilaterally in 15 and unilaterally in 32. In a separate study of 69 cadaver larynges, the openings were found in 39 (57%), appearing bilaterally in 16 and unilaterally in 23. In 51 laryngectomy specimens removed for squamous cell cancer and showing foramina, tumor was not observed to invade or traverse the foramen in a single case, even in those specimens with tumor overlying the foramen and displaying framework invasion at other sites. Invasion by cancer through the foramen appears to be prevented by a layer of fibroelastic tissue overlying the medial surface of the foramen, parallel to the inner surface of the thyroid lamina. This layer of fibroelastic tissue may represent perichondrium.

[Sonography of the larynx in childhood: new perspectives due to the use of computerized sonography. 1: Anatomy and method]

We report on new perspectives in diagnostic ultrasound of the larynx, which has become possible by applications of computer sonography. To our knowledge no such comprehensive ultrasonic diagnostics in children are reported as yet in the area of larynx. All examinations were performed with a computed sonography system (Acuson 128). We used a linear transducer with a penetration corresponding to 5 MHz an a resolution corresponding to 10 MHz. The frame rate was around 25 Hz and thus enabled a good reproduction of dynamic processes. As we could show, it is possible to visualize all significant structures of the larynx including the thyroid cartilage, the vocal ligament, the vocalis muscle, the arytenoid cartilage and the piriform fossa. Of course the vestibular fold and the cervical musculature are also demonstrable. The high frame rate of the instrument anaibled a good reproduction of dynamic processes. The sonographic demonstration of anatomical structures is possible as well as a functional diagnosis.

A complication of cricothyroid "minitracheostomy"--oesophageal perforation

Two patients suffered perforation of the oesophagus during attempted placement of a cricothyroid minitracheostomy. We discuss the probable mechanisms and means of preventing such a recurrence.

Functional anatomy of the larynx

The larynx serves three basic functions in humans. In order of functional priority they are protective, respiratory, and phonatory. This article discusses these three roles in terms of phylogeny, developmental anatomy, and neuromuscular reflex activity.

[Morphometry of the larynx in horizontal sections. Normal data for the quantitative evaluation of current imaging technics]

Laryngeal anomalies as a predisposing factor for pathogenesis of vocal disturbances have been discussed for a long time. Laryngeal structures can be made visible in vivo, and structural details be measured, only since the development of new imaging techniques, mainly of CT. As adequate descriptions have not been published in literature unto now, we measured horizontal sections of laryngeal specimens to collect reference data for a quantitative analysis of CT images. An evaluation technique was therefore developed, which, by clear definition of the planes and points of measurements, yields reproducible results. Direct measurement of the thyroid angles can be abandoned, since these can be easily calculated from the known distances.

Assessment of the cricoarytenoid joint: high-resolution CT scan study with histo-anatomical correlation

Eight normal larynges from autopsy cases were CT scanned and 1.5 mm contiguous slices in the cricoarytenoid joint region were taken. The larynges were then sectioned and stained for histological correlation. Different degrees of calcification, ossification and bone marrow cavitation of the cricoid and arytenoid cartilages were observed. This explained the variety of presentations of these structures on CT films. For example, the cricoarytenoid articular interspace was not always visible due to the saddle-shaped configuration of the joint superimposing cartilages on axial views. Features of normal CA joints on CT scan are discussed.

Histologic study of the growth of the subglottis after interruption of the circular structure of the cricoid

In a previous study in growing rabbits it was demonstrated that after resection of a ventral part of the cricoid the lumen of the subglottic airway developed normal size during further growth up to the adult stage. Histologic investigations of these cases suggest that a subepithelial network of elastic fibres, ventrally suspended to the thyroid and the tracheal rings, ensures the airway lumen and prevents the development of a subglottic stenosis. Resection of a ventral part of the cricoid including the adjacent soft tissue lining of the airway causes an irreversible loss of the supporting elastic layer and the formation of scar tissue resulting in a stenosis. It was concluded that the larynx and trachea can be considered as an inner, elastic tube (= conus elasticus) lined with epithelium, suspended to an outer, segmented cartilaginous tube. At the level of the subglottis an intact conus elasticus is of more importance for the normal development of the airway lumen in young rabbits than an intact ventral half of the cricoid ring.

Comparative anatomy of human and sheep laryngeal skeleton

In a macroscopical study the dimensions of the adult laryngeal skeleton of man and sheep were compared. In both species the data for male and female were evaluated separately. In contrast to pronounced differences in size between male and female human larynges, the dimensions of both sexes in sheep proved to be very similar. In respect of 7 size values, the sheep larynx falls in the range between the male and female human larynx. This applies to most values for height, the antero-posterior diameter and the inferior breadth of the thyroid cartilage. In the sheep cricoid, the height of the lamina and the inner transverse diameter correspond closely to the human counterpart. The most conspicuous differences vis-à-vis the human larynx are the narrowing of the upper portion, the absent upper incisure of the thyroid and the relatively large dimensions of the arytenoid cartilages in sheep. Since in sheep the dimensions at the level of the glottis and of the subglottic space are within the range of the human larynx, the suitability of the sheep larynx as a model for experimental clinical laryngology is discussed.

MRI of normal or cancerous laryngeal cartilages: histopathologic correlation

MRI appearances of laryngeal cartilages, normal or invaded by cancer, are still relatively unfamiliar to most clinicians. Twelve primary laryngeal tumors out of a series of 65 patients which have been investigated by MRI were examined postoperatively by macroscopic and microscopic sectioning of the surgical specimens. Images were obtained with a 0.6 Tesla superconductive system using a solenoid surface coil. The authors emphasize the value of a combined use of T1-weighted and balanced (relatively T2-weighted images with still T1-characteristics) Spin Echo images. T1-weighted images permit differentiation between pathological and normal bone marrow. Balanced images allow separation between nonossified cartilage and tumor tissue. MRI is an additional tool in the diagnostic workup of cartilage invasion by tumor.

Attachment of some internal laryngeal muscles at the base of the arytenoid cartilage

The attachments of the lateral cricoarytenoid muscle, thyroarytenoid muscle and interarytenoid muscle at the base of the arytenoid cartilage were studied in six adult larynges. Fresh specimens were treated by the acetylthiocholine method, sections were made with a freezing microtome and stained with Van Gieson stain. The muscle fibres could thus be traced to their fibrous tendinous attachments. The extent of attachment of each muscle at the base of the arytenoid was traced and its relationship to the maximum concavity of the arytenoid articular facet was computed. The lateral cricoarytenoid muscle attachment extends anteromedially from the muscular process but falls short of the anterior border with a variation of 5,800M-7,800M. These variations are statistically significant. The thyroarytenoid and interarytenoid muscles' attachments show similar variations as described and discussed. The interpretation of these results is discussed and conclusions are drawn as regards the influence of these variations on the function of the glottis.

Posterior glottis. Morphological study in excised human larynges

Two sets of investigations were conducted with excised human larynges. The glottis was closely observed and photographed from above and below in three conditions: neutral, adduction, and abduction. The structure surrounding the posterior glottis was histologically investigated in the same three conditions. The results are as follows. The structure surrounding the posterior glottis consists of three portions: the posterior wall of the glottis, the lateral wall of the posterior glottis, and the cartilaginous portion of the vocal fold. During vocal fold adduction, the posterior part of the larynx closes completely not at the glottis but at the supraglottis, resulting in formation of a conic space in the posterior glottis that can be viewed only from below. The posterior glottis accounts for approximately 35% to 45% of the entire glottic length and 50% to 65% of the entire glottic area. The mucosa of the posterior glottis has ciliated epithelium. The lamina propria consists of two layers. The posterior glottis can be regarded as a respiratory glottis.

Magnetic resonance imaging of the larynx: a correlation with histologic sections

To date, high-resolution computed tomographic (CT) scanning has proved to be the most valuable preoperative study for the evaluation of the anatomic extent of head and neck cancers. Now, with the development of magnetic resonance (MR) imaging, the prospect of having an equally reliable test without associated radiation exposure has emerged. This study is designed to compare MR images of the larynx with corresponding histologic sections obtained by step-serial sectioning of whole organ specimens. Images were generated by a 0.3 Tesla permanent magnet MR imager. Additional correlation with CT scans was obtained when possible. CT resolution proved to be slightly superior in the axial plane but markedly inferior to MR imaging in the coronal and sagittal planes. Overall, MR imaging appeared to have good resolution of the larynx.

Anatomical observations in the pharynx of the mouse with special reference to the nasopharyngeal hiatus (Wood Jones)

The mouse pharynx, especially the muscles, was anatomically studied in detail considering the structures of the laryngeal cartilages and the hyoid bone. The nasopharyngeal sphincter was formed by the palatopharyngeus and the levator palati muscles. It was suggested that the former contracted the 'palatopharyngeal eminence' (named by the present authors) and the latter drew up the soft palate, then the nasopharyngeal hiatus was closed. At the rostral end of the esophagus, there existed the 'thyro-pharyngo-esophageus muscle', denominated by the present authors. It was suggested to represent in the area of the esophagopharynx and to compress the tube by any sphincteric functions.

Relationship of laryngeal dimensions to body size and gestational age in premature neonates and small infants

The larynges of 27 infants weighing between 250 gm and 9160 gm were studied. Twenty-two neonates were from 24 to 40 weeks' gestational age. Five subjects died more than 6 weeks post partum but were included because of their small size. Relationships of larynx size to the standard clinical measurements of crown-heel length, crown-rump length, head circumference, and gestational age were developed. Cartilage size relationships to these measurements were found to be linear. Glottic length related linearly to crown-rump length but related in a curvilinear way to crown-heel length, head circumference, and gestational age. A guide to the choice of endotracheal tube sizes for small infants is suggested.