ch it communicates with the laryngopharynx, to the level of the inferior border
of the cricoid cartilage, where it is continuous with the cavity of the trachea.
- The superior and inferior projecting folds of mucous membrane on each side, called the vestibular folds divide the larynx into three
- Superior to the vestibular folds, the cavity is called the vestibule
of the larynx.
- Between the vestibular folds, superior to the vocal folds is the ventricle
of the larynx.
- This is the smallest of the three cavities of the larynx.
- It extends laterally between the two folds as the sinus of the
- From each sinus, a saccule of the larynx passes
superiorly between the vestibular fold and the thyroid lamina.
- The inferior compartment of the larynx is called the infraglottic
- It extends from the vocal folds to the inferior border of the cricoid cartilage, where
it is continuous with the cavity of the trachea.
The Vocal Folds (pp. 843-4)
- The vocal folds (vocal cords) are concerned with the production of
- The apex of each wedge-shaped vocal fold projects medially into the laryngeal cavity,
and its base lies against the lamina of the thyroid cartilage.
- Each vocal fold consists of the vocal ligament, the conus elasticus, muscle fibres, and
a covering of mucous membrane.
- The rima glottidis is the aperture between the vocal
- The term glottis refers to the vocal folds, the rima
glottidis, and the narrow part of the larynx at the level of the vocal folds.
- The glottis is the part of the larynx most concerned with sound
- The shape of the rima glottidis varies according to the position of the vocal folds.
- During ordinary breathing, it is narrow and wedge-shaped; during forced respiration, it
- The vocal folds are closely approximated during speaking so that the rima glottidis
appears as a linear slit.
The Vestibular Folds (p. 844)
- These folds extend between the thyroid and arytenoid cartilages and play
little or no part in voice production.
- They consist of two thick folds of mucous membrane enclosing the vestibular ligaments.
- The space between the vestibular ligaments is called the rima
- The vestibular folds are part of the protective mechanism by which the larynx is closed
during swallowing to prevent the entry of food and foreign particles into it.
Muscles of the Larynx
Extrinsic Muscles (pp. 844-5)
Intrinsic Muscles (pp. 845)
- The intrinsic muscles are concerned with the movements of the
laryngeal parts, making alterations in the length and tension of the vocal
folds and in the size and shape of the rima glottidis in voice production.
- All intrinsic muscles of the larynx are supplied by the recurrent
laryngeal nerve, a branch of the vagus
nerve (CN X) except the cricothyroid muscle, which is
supplied by the external laryngeal nerve.
Adductors of the Vocal Folds
- The lateral cricoarytenoid muscles arise from the
lateral portions of the cricoid cartilage and inserts into the muscular processes or the
- These pull the muscular processes anteriorly, rotating the arytenoid cartilages so that
their vocal processes swing medially.
- These movements adduct the vocal folds and close the rima glottidis.
Abductors of the Vocal Folds
(pp. 845, 847)
- The principle abductors are the posterior cricoarytenoid muscles.
- These muscles arise on each side from the posterior surface of the lamina of the cricoid
cartilage and pass laterally and superiorly to insert into the muscular processes of the
- They rotate the arytenoid cartilages, thereby deviating them laterally and widening the
Tensors of the Vocal Folds (p.
- The main tensors are the triangular cricothyroid muscles.
- These are located on the external surface of the larynx between the cricoid and thyroid
- The muscle on each side arises from the anterolateral part of the cricoid cartilage and
inserts into the inferior margin and anterior aspect of the inferior horn of the thyroid
- These muscles tilt the thyroid cartilage anteriorly on the cricoid cartilage, increasing
the distance between the thyroid and arytenoid cartilages.
- As a result, the vocal ligaments are elon