Laryngeal Mechanics Quiz

The posterior cricoarytenoids are the only intrinsic muscles that are ABductors (openers) of the vocal folds. They rock the arytenoids back dorsally to open the glottis and are innervated by the recurrent laryngeal nerve.

The lateral cricoarytenoids are intrinsic ADductor muscles. They pull the muscular processes anteriorly and vocal processes medially to approximate and slightly tense the vocal folds. This is called medial compression, which is the pre-phonatory position. They are innervated by the inferior laryngeal nerve, also known as the vagus nerve.

The cricothyroids are intrinsic ADductor muscles. They increase the distance between the thyroid and arytenoid cartilages, stretching and tensing the vocal folds. This action increases the pitch of the voice. The cricothyroids are innervated by the superior laryngeal nerve.

The transverse arytenoid is a single, unpaired, intrinsic muscle. It wraps around the arytenoids and pulls them together, approximating the vocal folds. It is innervated by the recurrent laryngeal nerve.

The oblique arytenoids are paired, intrinsic ADductor muscles. They originate from the muscular process of one arytenoid, extend obliquely to the apex of the opposite arytenoid, and continue to the lateral border of the epiglottis. They pull the arytenoids medially, approximating the vocal folds.

The thyroarytenoid muscles are intrinsic muscles that form the bulk of the muscular portion of the vocal folds. These muscles can shorten and thicken the vocal folds, lowering pitch. The lateral portion is the thyromuscularis and the medial portion is the vocalis, which provides fine control over phonation.

The myoelastic aerodynamic theory explains how phonation occurs. The theory combines the actions of the muscles (myo), elasticity of the vocal folds (elastic), and the dynamics of airflow (aero).

Frequency is the number of vibrations per second. A higher frequency means more vibrations per second, resulting in a higher pitch. A lower frequency means fewer vibrations per second, resulting in a lower pitch.

An octave is the interval between two notes where the frequency ratio is 2:1. For example, Middle C on a piano has a frequency of 261 Hz, and C one octave higher has a frequency of 522 Hz.

Intensity, also known as loudness, is measured in decibels (dB). It relates to the amount of energy expended during sound production. Greater energy results in a louder sound.

Quality or timbre refers to the distinctive character of a sound. It's determined by the combination of sounds that make up a complex tone. A pure tone has a single frequency, while a complex tone has a fundamental frequency and overtones that are multiples of the fundamental frequency.

Overtones, also called harmonics, are frequencies that are whole-number multiples of the fundamental frequency. For example, the fourth harmonic of 261 Hz (Middle C) is 1044 Hz.

Periodic sounds are produced with overtones that are harmonically related and perceived as pleasant. These sounds have a continuous, regular pattern of vibration. Examples include normal speaking voice and vowels.

Aperiodic sounds lack the harmonic relationship of periodic sounds, meaning they have components at all frequencies. They are transient, with vibrations that start and stop suddenly, not repeating. Examples include consonants, turbulence, and a hiss.

Normal phonation involves the vocal folds approximating along the entire anterior-posterior dimension. This is called phonatory expiration, or simply phonation.

A slight posterior glottal chink is a subtle opening in the posterior part of the vocal folds. This is more common in females and is not a pathology, but a variation of normal.

Non-phonatory expiration occurs when the vocal folds are abducted but not at extremes. There is no voice production, only exhaling.

Forced inspiration is when the vocal folds are widely abducted to allow for a deep inhalation.

Whisper phonation involves a chink of the cartilaginous portion of the vocal folds with anterior 2/3 approximation, but not firm closure. This creates turbulence and the perception of a whisper. Whispering is not ideal for the vocal mechanism because it is highly aperiodic.

Sarcopenia is the loss of muscle tissue that occurs naturally as part of aging. It is a healthy phenomenon in older adults, not a disorder. To combat it, staying physically active can help.

Presbyphonia refers to natural voice changes associated with aging. It is not a disorder but a physiological process.

The S/Z ratio compares the maximum duration of sustained /s/ and /z/ phonemes. It screens for potential vocal pathologies. A normal ratio is 1:1. A ratio greater than 1.2 may indicate a need for further assessment.

The Consensus Auditory-Perceptual Evaluation of Voice (CAPE-V) is a standardized tool for evaluating and documenting auditory-perceptual judgments of voice quality.

The Voice Handicap Index (VHI) is a self-rated instrument that measures the functional, physical, and emotional impact of a voice disorder on a patient's daily life. It is a measure of the patient's perception of their voice disorder.

Jitter refers to the short-term variability in frequency, or pitch, of the voice.

Shimmer measures the short-term variability in amplitude, or loudness, of the voice.

Functional voice disorders are caused by incorrect use of the phonatory system. They are divided into muscle tension dysphonia and psychogenic voice disorders.

Muscle tension dysphonia is a voice disorder related to misusing the vocal mechanisms, leading to a hypertensive type of dysphonia. It can lead to vocal pathologies such as nodules and polyps.

Psychogenic voice disorders are caused by emotional trauma or conflict that manifests itself in voice. This can lead to conversion aphonia, where the patient is unable to produce any sound.

Ventricular phonation is a voice disorder where the false vocal folds are involved in phonation. This can result in a lower fundamental frequency due to the increased mass of the false folds.

Vocal nodules are bilateral lesions that typically appear as white bulges at the junction of the anterior and posterior thirds of the vocal folds. They are caused by chronic vocal misuse and excessive tension. Over time, they can become larger, heavier, and stiffer, resulting in increased dysphonia and breathiness in the voice.

Vocal polyps are unilateral lesions that often appear at the junction of the anterior and posterior thirds of the vocal folds. They are typically caused by a single traumatic vocal event, but can be due to vocal misuse . They can be larger and softer than nodules.

Reinke's edema is a vocal fold thickening that occurs due to chronic vocal misuse and behaviors. It involves a buildup of fluid under the vocal fold cover and is often associated with chronic smoking.

Contact ulcers, or granulomas, are lesions that typically appear in the posterior region of the vocal folds. They can be caused by organic factors such as acid reflux or functional factors such as hyper-function. They are often related to chronic throat clearing, coughing, and hard glottal attacks. While they can be minimal in dysphonia, they can be unilateral or bilateral.