Partially abduct with inhalation and partially adduct with end-exhalation.
Are the functional unit of the larynx.
Function depends on neuromuscular activity for gross movements and for pliability for phonation.
Phasic vocal cord movement is physiologic.
Open vocal folds facilitate breathing, while closing the vocal folds protects airway during deglutition.
The vocal cords consist of squamous epithelium, lamina propria and muscle.
The superficial layer of the lamina propria has a most important role in phonation.
During deglutition the larynx must move superiorly and anteriorly to open the esophageal inlet.
Forced exhalation of air against closed vocal cords enables phonation.
Variation in pitch is achieved through shortening and lengthening of the vocal folds.
Allow unimpeded flow of air to the lungs and outward to the atmosphere while maintaining positive airway pressure during expiration.
Dysfunction characterized by abnormal adduction of the vocal cords during the respiratory cycle, producing airflow obstruction at the level of the larynx.
Dysfunction mimics asthma.
Motion confirmed by laryngoscopy.
Loss of vocal fold pliability is from scars as a result of long term vocal misuse, trauma, or surgery.
The larynx serves as an upper airway valve to keep the lungs expanded.
The larynx is heavily innervated and its size is regulated by activation of striated muscle under voluntary and reflexive control.
Laryngeal and respiratory motor neurons regulate glottis size, as does influence of reflex activity of pulmonary and laryngeal receptors.
Glottic size can be altered by reflex activity from pulmonary and laryngeal receptors.
When integrated function of the vocal cords is altered episodically it causes intermittent functional airway obstruction, resembling vocal cord paralysis, epiglottitis, laryngospasm, angioedema and asthma.
Other causes of vocal cord dysfunction include: the presence of gastric mucosa in the upper esophagus, and exposure to chlorine, glutaraldehyde or eucalyptus.
Dysfunction hypothesized to be related to the vagus nerve by lowering the threshold for stimuli and produce vocal cord spasm or to precipitate the abnormal adduction of vocal cords.
Dysfunction primarily related to gastroesophageal reflux, laryngopharyngeal reflux and neurologically based dystonias.