258

Front 1

SUPERIOR LARYNGEAL NERVE

External Laryngeal Nerve

Back 1

3. External laryngeal nerve: descends with the superior thyroid artery,
inferior to the oblique line of the thyroid cartilage, deep to the sterno-
thyroid and superficial to the inferior pharyngeal constrictor; innervates
the cricothyroid (as well as part of the inferior pharyngeal constrictor)

Front 2

RECURRENT LARYNGEAL NERVES

RIGHT VS. LEFT

Back 2

B. Recurrent laryngeal nerves

1. The right and left recurrent laryngeal nerves loop posteriorly around
the right subclavian artery and aortic arch, respectively, and ascend in
the grooves between the trachea and esophagus on their respective sides;
as they ascend posterior to the lobes of the thyroid gland, they enter the
larynx posterior to the cricothyroid articulation, between the inferior
pharyngeal constrictor and esophagus

Front 3

RECURRENT LARYNGEAL NERVES

INNERVATION?

Back 3

B. Recurrent laryngeal nerves

2. Innervate all the muscles of the larynx, except the cricothyroids (which
are innervated by the external laryngeal nerves), and provide sensory
innervation to the laryngeal mucosa inferior to the vocal folds

Front 4

CC

EXTERNAL LARYNGEAL NERVE INJURY

-when?

Back 4

C. Clinical notes

1. External laryngeal nerve injury may occur when securing the superior
thyroid artery during a thyroidectomy; paralysis of the cricothyroid
muscle, and loss of its function in tensing the vocal ligaments, may re-
sult in hoarseness

Front 5

CC

BILATERAL INJURY TO:
RECURRENT LARYNGEAL NERVES

Back 5

C. Clinical notes

2. Bilateral injury to the recurrent laryngeal nerves, perhaps during a
thyroidectomy, produces a narrowing of the rima glottidis as a result of
paralysis of the posterior cricoarytenoid muscles and loss of their func-
tion as the only abductors of the vocal ligaments; unopposed adduction
of the vocal ligaments by the cricothyroid muscles may require surgical
intervention to correct respiratory distress

Front 6

SUPERIOR LARYNGEAL ARTERY

Back 6

A. Superior laryngeal artery: arises from the superior thyroid artery; accom-
panies the internal laryngeal nerve through the thyrohyoid membrane and
supplies the superior part of the larynx

Front 7

INFERIOR LARYNGEAL ARTERY

VEINS

LYMPHATICS

Back 7

B. Inferior laryngeal artery: arises from the inferior thyroid artery; accompa-
nies the recurrent laryngeal nerve into the larynx (between the inferior
pharyngeal constrictor and esophagus) and supplies the inferior part of the
larynx

C. Veins: accompany their respective arteries

D. Lymphatics: drain to deep cervical nodes