lar 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 elongated and tightened and the pitch of the voice
Relaxers of the Vocal Folds
- The principle relaxers of these folds are the broad thyroarytenoid
- They arise from the posterior surface of the thyroid cartilage near the median plane and
insert into the anterolateral surfaces of the arytenoid cartilages.
- One band of its inferior deep fibres, called the vocalis muscle,
arises from the vocal ligament and passes to the vocal process of the arytenoid cartilages
- The thyroarytenoid muscles pull the arytenoid cartilages anteriorly, thereby slackening
the vocal ligaments.
- The vocalis muscles produce minute adjustments of the vocal
ligaments (e.g., as occurs during whispering). They also relax parts of the
vocal folds during phonation and singing.
Blood Supply of the
Larynx (p. 847)
- The superior and inferior laryngeal arteries supply the
- They are branches of the superior and inferior thyroid arteries respectively.
- The superior laryngeal
artery runs with the internal branch of the superior laryngeal nerve through
the thyrohyoid membrane, and then branches to supply the internal surface of the larynx.
- The inferior laryngeal
artery runs with the inferior laryngeal nerve and supplies the mucous membrane
and muscles of the inferior aspect of the larynx.
Innervation of the
Larynx (p. 848-9)
- The laryngeal nerves are derived from the vagus
nerve (CN X) through the superior laryngeal nerve and the
recurrent laryngeal nerve.
- All intrinsic muscles, except cricothyroid, are innervated by the recurrent
laryngeal nerve with fibres from the accessory nerve (CN XI). The external laryngeal nerve supplies the cricothyroid muscle.
- The supraglottic portion of the laryngeal
mucosa is supplied by the internal laryngeal nerve,
a branch of the superior laryngeal nerve.
- The infraglottic portion of the laryngeal mucosa is
supplied by the recurrent laryngeal nerve.
Drainage of the Larynx (p. 849)
- The lymph vessels superior to the vocal folds accompany
the superior laryngeal artery through the thyrohyoid membrane and drain into 