hi let's talk about the laryngeal membranes and cavities in this video we'll discuss
the intrinsic laryngeal membranes and their major features and functions we'll also relate the
anatomy of the larynx and surrounding structures to methods of gaining airway access so there are
two intrinsic laryngeal membranes there are a pair of quadrangular membranes which rest superiorly
and then there is a singular conus elasticus which rests inferiorly now it's probably worth noting
that these two sets of membranes are separated by the laryngeal ventricles so this space here
is going to separate the quadrangular membranes above from the conus elasticus below now in this
case the posterior wall of the larynx has been incised and then abducted away so that we can see
these features of the membranes so let's let's look at the
quadrangular membranes so there are two quadrangular membranes
and these one between the arytenoid cartilage is in the thyroid cartilage and the
epiglottis there are two main features of these cartilages i'm sorry of these uh
of these membranes the uh the first are the area epiglottic ligaments these are
epiglottic ligaments provide lateral structure to the laryngeal inlet
and the next are the vestibular ligaments also known as the ventricular ligaments
these span the distance between the arytenoid cartilages there and the thyroid cartilage these
vestibular ligaments when they're invested by mucosa are known as the vestibular folds
they're also known as the false vocal folds so there are two of these quadrangular membranes
one on either side and their function together is to really funnel air into the larynx below
the laryngeal ventricle we have the conus elasticus the conus elasticus's function
is to funnel air out specifically towards the rima glottidis and let me
clear all this out of the way so the superior most part of the conus elasticus on either side
are the vocal folds running between the vocal processes of the arytenoid cartilages and the
thyroid cartilage there those ligaments when invested by mucosa are the vocal folds and
below that we have a couple of features laterally here we have the lateral cricothyroid ligaments
and then medially here we have the median cricothyroid ligament so the the two of these
uh sets of ligaments are going to span the distance between the thyroid cartilage the
cricoid cartilage and even the arytenoid cartilage we'll see later how that uh median cricothyroid
ligament comes into play with respect to managing an airway in an emergency
but first let's take a look at the laryngeal cavities so the laryngeal cavities are just
spaces and these spaces are going to be important if we're going to talk about airway management so
the path of gas exchange let's just go one way in now air is going to come from the oropharynx and
the laryngopharynx in through the laryngeal inlet and the space there is the laryngeal vestibule
now inferior to the laryngeal vestibule there's going to be two sets of folds these are going to
be vestibular folds or ventricular folds they're the same thing and then the space between those
folds is the rima vestibuli there then can continue down and it can pass through the
laryngeal ventricle which we can see there and then there's another set of folds the vocal folds
and the space between the vocal folds is known as the rima glottidis
together the rima glottidis plus the vocal folds is known as the glottis
below the rhema glottidis so air is funneling through there we have the infraglottic cavity
which is continuous with the lumen of the trachea so in through the laryngeal inlet to the laryngeal
vestibule through the rima vestibuli through the laryngeal ventricle through
the rima glottidis through the infraglottic cavity through the lumen of the trachea
now airway access can be achieved through some of these elements and it really depends on if
this is an emergent situation or if we're talking about long-term care
this is an emergent situation one may perform a cricothyrotomy in order to do so you would palpate
the laryngeal prominence and then you would move inferior to that and you can feel a little divot
and then you can palpate the cricoid cartilage so that divot between palpable elements of the
larynx one may incise the skin and then deep to that they would incise that median cricothyroid
ligament so that is a cricothyrotomy it's a very straightforward procedure
there aren't any vascular elements in the way that are very problematic there are palpable
landmarks uh it is a very small um uh airway that that can happen and it's also going to
interfere with the elements of the larynx so that's that's going to be somewhat problematic so
if the airway needs managed for long-term care one may perform a tracheotomy and by one i mean
a surgeon can do this this is done under surgical guidance in a sterile
arena and what a tracheotomy or a tracheostomy is is one goes maybe one centimeter superior to the
jugular notch there and they can perform a longitudinal incision through the skin and
then they may move vascular elements out of the way so here we can see the inferior thyroid veins
draining the thyroid gland of blood down to that left brachiocephalic vein we
may have a thyroid ima artery so about 10 percent of the population will have an artery in the way
there and that would be very problematic owing to the blood pressure in an artery
or the the thyroid gland itself may be very low and that might require some management
so a tracheotomy is not something that is is performed emergently it's it's done surgically
and that leads us to our assessment question of the video and that is which space separates
elements of the quadrangular membranes from the conus elasticus is it the infraglottic cavity
no the laryngeal vestibule close but no laryngeal ventricle yeah sounds good
rima glottidis close but no rima vestibuli no recall that the quadrangular membranes
their inferior most parts are those vestibular ligaments the superior most folds of the conus
elasticus are the vocal ligaments and then the space between them is the laryngeal ventricle
see final answer thank you very much for your time