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.