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J Pesák

Publications and source records attributed to J Pesák.

25 records · Page 2Linked to original sources
PubMed1989

Role of the thyroid cartilage in phonation.

Larynx is a part of the respiratory system and is supposed to be a complex apparatus responsible for the phonation-creation of voice. However, the extensive anatomical knowledge about the larynx does not correspond to an obscure speculation about creation of voice. Therefore the function of the larynx can be compared with the function of electro-acoustic transducers and on this basis certain roles can be ascribed hypothetically to the functional details of phonation system. The thyroidal cartilage seems to be ideal for such a comparison. Diffusion of acoustic signal by densing and diluting of an elastic milieu is due to the initial stimulus mediated by a solid and elastic sound. In case of vocal system, the initial stimuli occur stimultaneously at two sounds that behave as membranes of coaxial mechanic-acoustic resonators in the function of a radiator. Vocal cords represent a membrane of more subtile system, and the thyroid cartilage is a membrane of more robust system. The mechanism of oscillation is the subject of the present communication. It was concluded that the thyroid cartilage is not only a passive shield protecting the fine glottic structures, but on the contrary an active element of this mechanic-acoustic radiator. The recorded movements of the thyroid cartilage enabled to subtract the presence of neuroreflexive activity accompanying the vocal cycle. The anatomical structures in the vicinity of the thyroid cartilage indicate possible modifications of its motion so that the laryngeal articulation can be supposed.

Humans↗
PubMed1989

Specifying the function of arresting and centering mechanisms of the larynx.

A specific function of larynx represents the creation of voice-phonation, whose mechanisms are not as of yet sufficiently known. Thus, quite a lot of physiological phenomena cannot be properly recognized. Some anatomical details are not described at all and in the figure part of literature are left out in spite of their evident existence. These critical remarks pertains wholly to the up to date's knowledge of the role of the pseudo voice ligaments. The very existence of the pseudo voice ligament rather puzzles. The pseudo vocal fold are supposed to be immobile. There's a good reason to suppose that the pseudo voice ligaments follow a very important movent, though unnoticeable, in the direction of the elastic fibres, right at the phonal position. The fibres of the pseudo voice ligaments are drawn dorsally at which they draw upsligh the thyroid cartilage. It looks like the elastic fibres of the pseudo voice ligaments were functioning as a centering mechanism known with the electro-acoustical systems. As if this arrangement was to bring the thyroid cartilage in its role of a membrane into such position in which it could vibrate in both its directions, dorsal and ventral. The pseudo glotic ligaments represent at the same time a part of an arresting arrangement which damps in its respiration position the flexible prestress of the thyroid cartilage. If it were not so, the thyroid cartilage would vibrate automatically even in respiration producing at the same time unwanted sounds.

Humans↗
PubMed1989

Function of speech organ pitch mechanism.

Singing is generally known to be associated with lengthening of vocal ligaments and increasing frequency. At the same time, the anterior vibrating part of both the vocal ligaments become shortened. No explanation based on anatomical grounds has so far been given accounting for this phenomenon and its mechanism. The present paper advocates the crucial role of the elastic fibres (conus elasticus) connecting the upper edge of the cricoid cartilage with the vocal ligament on the circumference in the function of the speech organ pitch mechanism. The vocal ligament is a thickened free cranial margin of this part of the fibroelastic membrane. As the anterior arcus of the cricoid cartilage is approaching the midline of the thyroid cartilage during pitch production the elastic fibres are slackened in their front parts and stretched in their posterior parts, while the vocal ligaments are being stretched. This results in fixation of the posterior node point of the anterior vibrating vocal cord portion and inhibition of their posterior part.

Humans↗
PubMedDate not supplied

Shortening of the front vibrating part of the vocal folds in phonation.

We have tried to make use of the opportunity of repeated observations through the analysis of the recorded movements of the phonating vocal folds by means of the phonating vocal folds through indirect videolaryngostroboscopic technique. The results of our investigation correspond, among others, with Hála and Sovák's diagrammatic description of continual and gradual changes in the vibration of the vocal folds in an uninterrupted sequence of tones of the human voice. In the initial chapter mention has been made of Hála and Honty's works and of Pressmann's work dealing with the described behaviour of the glottis when phonating high-pitched tones. The conclusions analogous to our findings have also been described by means of stereoscopically measuring the length of the phonating vocal folds. In conclusion, by measuring the distances between the anterior commissure and the junction between the membranous part of the vocal fold and vocal process of the arytenoid and the anterior commissure to the posterior nodal point of the vibrating part of the vocal folds we have verified the correctness of the findings published by Czermak, Hála and Honty, Pressmann, and Sovák, who pointed out the phenomenon of the shortening of the front vibrating part of the vocal folds in phonating high-pitched tones of the human voice.

Adult↗