Muscles of Larynx Anatomy
1.
Oblique arytenoid muscles
2.
Transverse arytenoid muscles
Origin:
Arise
from the arytenoid cartilages.
Insertion:
Attach
to the opposite arytenoid cartilage.
Action: Close the inlet of the larynx by adducting the arytenoid cartilages. This narrows the rima glottidis, the space between the vocal folds.
Innervation:
Recurrent
laryngeal nerve of the vagus.
Comment:
Some
muscle fibers of the oblique arytenoid continue superiorly as the
ary-epiglottic muscle.
Clinical:
The
vocal folds are controlled by the laryngeal muscles, all of
which are innervated by the vagus nerve (CN X). During quiet respiration, the
vocal folds are gently abducted to open the rima glottidis (space between the
folds). In forced inspiration (taking a rapid, deep breath), the folds are
maximally abducted by the posterior crico-arytenoid muscles, further enlarging
the rima glottidis. During phonation, the folds are adducted and tensed to
create a reed-like effect (similar to a reed instrument), causing vocal fold
mucosal vibrations that produce sound that is then modified by the upper airway
(pharynx, oral cavity, tongue, lips, nose, and paranasal sinuses). Closure of
the rima glottidis occurs when holding your breath or when lifting something
heavy (the Valsalva maneuver), and the folds are
completely adducted.
1.
Ary-epiglottic part of oblique arytenoid muscle
2.
Posterior crico-arytenoid muscle
3.
Thyro-epiglottic part of thyro-arytenoid muscle
4.
Thyro-arytenoid muscle
5.
Lateral crico-arytenoid muscle
6.
Vocalis muscle
7.
Vocal ligament
8.
Conus elasticus
Comment:
The
muscles of the larynx are small. They act on the laryngeal
cartilages.
The
most superior portion of the conus elasticus is thickened and forms the vocal
ligament. The vocal folds themselves contain a small amount of muscle called
the vocalis muscle, which is derived from some of the fibers of the
thyro-arytenoid muscle.
With
the exception of the cricothyroid, all the intrinsic muscles of the larynx are
innervated by the recurrent laryngeal nerve of the vagus. All of these muscles
are derived embryologically from the 4th through 6th pharyngeal
(branchial) arches.
Clinical:
The
vocal folds are controlled by the laryngeal muscles, all of
which are innervated by the vagus nerve (CN X). During quiet respiration, the
vocal folds are gently abducted to open the rima glottidis. In forced
inspiration, the folds are maximally abducted by the posterior crico-arytenoid
muscles, further enlarging the rima glottidis. During phonation, the folds are
adducted and tensed to create a reed-like effect, causing vocal fold mucosal
vibrations that produce sound that is then modified by the upper airway
(pharynx, oral cavity, tongue, lips, nose, paranasal sinuses). Closure of the
rima glottidis occurs when holding your breath or when lifting something heavy,
and the folds are completely adducted.
