hi let's talk about the intrinsic laryngeal muscles
as you may recall the intrinsic laryngeal muscles are muscles which attach one element
of the laryngoskeleton to another element of the laryngoskeleton most of them are innervated by the
recurrent laryngeal nerves the exception to that is this first muscle that we'll
start with the cricothyroid pay attention to the names of the intrinsic laryngeal muscles because
a lot is revealed in particular what elements of the laryngoskeleton these muscles attach
so the cricothyroid muscles run from the anterior aspect of the cricoid cartilage
up to the thyroid cartilage and when they are stimulated by those external branches of the
superior laryngeal nerves which we can see coming down there they tip the thyroid cartilage
anteriorly and inferiorly so they're affecting motion at that cricothyroid joints
and that is going to put more tension on the vocal ligaments and tension is proportional
to pitch so more tension equals more pitch these are elevators of pitch
the next muscles that i'd like to show you are the arytenoid muscles the arytenoid muscles
get their name from the fact that they attach the arytenoid cartilages to one another when they pull
they are going to adduct the arytenoid cartilages together and if we were to think of this from
a superior view so those would be the vocal ligaments
these would be the arytenoid cartilages by adducting those arytenoid cartilages together one
is going to adduct the vocal folds and therefore it's going to make the rhema glottidis narrower
which in fact is the position for phonation because those folds need to be relatively
near each other in order for them to vibrate they need to be in the path of the air now there are
two types of fibers for the arenoid muscles that we call different muscles they're the transverse
transverse are the ones whose fibers are running like so
and then there are the oblique and the oblique fibers
run like this obliquely see very well named
they both work together they're both innervated by the recurrent laryngeal nerves uh and the oblique
arytenoid muscles actually have an airy epiglottic part which runs in the air epiglottic folds to
help constrict or narrow the laryngeal inlet to help that function more of as a sphincter for air
now finally we have the crico-arytenoid muscles there are both lateral and posterior critical
or eating muscles they both originate on the cricoid cartilage albeit in different places
their names will reveal that and they both also attach to the muscular process of the
arytenoid cartilage so if we were to draw this out with our vocal ligaments like so
these are the vocal processes to the anterior and then laterally there are muscular processes
to which these cricoarytenoid muscles attach the posterior crico-arytenoid muscles come from the
posterior aspect of the cricoid cartilage attached to those muscular processes such that when they
pull the arytenoid cartilage pivots laterally so that muscular
process goes out what that does is it apducts it abducts the vocal folds
so as to make the rima glottidis larger so this is a position for wholesale ventilation
the other muscle and you're not responsible for finding this in lab is going to be the lateral
crico-arynoid muscle we can see here that the thyroid lamina has been cut and reflected we can
see coming from the cricoid cartilage there up to the muscular process of the retinal
cartilage there which is where the posterior crico-arytenoid muscle goes those muscles
are going to pull the muscular processes medially so as to adduct the vocal folds
to bring them into the position for phonation because when you bring the vocal folds in the
airway they have the opportunity to vibrate with with exhalation which is the basis for phonation
so we've discussed the uh the greatest hits of the intrinsic uh laryngeal
muscles uh cricothyroid uh a retinoid muscles oblique and transverse as well as
crico-arytenoid muscles lateral and posterior crico-arytenoid muscles thank you for your time