Download BIO171_04_Larynx [screen displays model of larynx] [Barbara

BIO171_04_Larynx.rtf
[screen displays model of larynx]
[Barbara Davis speaking] Welcome to the respiratory system. In this video we’re going to cover
the larynx in more detail, so let’s get oriented. Here is the hyoid bone. Remember the hyoid
bones claim to fame is that it’s the only bone in the body not connected to another bone.
There’s a membrane that connects the hyoid bone here to the larynx. This specific part of the
larynx is called the thyroid cartilage, so this membrane — this connective tissue structure — is
called the thyrohyoid membrane because it connects the thyroid cartilage and the hyoid bone.
Peeking above the hyoid bone, we can see another one of the singular cartilages of the larynx,
which is the epiglottis. We’ll be able to see this one more clearly in the posterior view.
Below the thyroid cartilage we have the last singular cartilage of the larynx — the cricoid
cartilage. The cricoid cartilage can be confused for one of the tracheal cartilages, but notice that
it is a little bit thicker, particularly on the lateral sides here.
So, from top to bottom we’ve got epiglottis, thyroid cartilage, cricoid cartilage. We can also see
the thyroid gland here; it’s butterfly shaped. We’ve cut away this part of the thyroid gland so we
could see the trachea. So, the trachea is the airway that extends from the larynx — specifically,
the cricoids cartilage of the larynx — into the thoracic cavity. The trachea is composed of
cartilaginous rings, called c-rings, or tracheal cartilages, that are connected by this connective
tissue.
So, let’s turn the larynx around so we can see some of the structures on the posterior view. In
this view, beginning at the bottom here, we can see that the trachea — the rings are c-shaped,
that’s where the name comes from, because the rings do not connect on the posterior aspect. The
two ends of the cartilage here are connected by connective tissue and a smooth muscle called the
trachealis.
We can see the thyroid gland coming around a little bit to the posterior aspect. Here we can see
some of the paired cartilages of the larynx. The biggest one here is the arytenoid cartilage. This
is one arytenoid cartilage; here is the other of the pair. Right on the superior tip of the arytenoid
cartilage — these tips here — is the corniculate cartilage. If you look closely, you can see that
© 2010 Eastern Kentucky University. All Rights Reserved.
ANF
Page 1 of 2
BIO171_04_Larynx.rtf
they resemble a candy corn — so, the name corniculate cartilage. The cuneiform cartilage is not
readily seen in this view. We will examine it on the tracheal bronchi model.
We can see here the epiglottis is elongated, and in the superior view we’ll see how the epiglottis
actually folds down over the opening to the larynx.
Here we are looking down the superior aspect of the larynx. So, let’s get oriented. The structure
here, the horseshoe-shaped structure, is the hyoid bone. Here we can see the epiglottis, which
we’ll demonstrate the function of in just a moment. This is the arytenoid cartilage on one side;
this is the arytenoids cartilage on the other side. Each arytenoid cartilage is attached to a
membranous structure called the true vocal fold, or the true vocal ligament. At the tip of the
arytenoids cartilage we can see the corniculate cartilage.
The arytenoids cartilages can swivel, as we can see in the model here. As they swivel, they
create an opening between the true vocal ligaments called the glottis. So, the glottis is the
opening of the larynx. When the membranes close the glottis and the epiglottis is pushed down,
then we have protection in the respiratory tract when we swallow liquids and fluids.
This concludes our view of the larynx in detail.
[video ends]
© 2010 Eastern Kentucky University. All Rights Reserved.
ANF
Page 2 of 2