Unpaired larynx cartilage

Attachment:  attached at the inner aspect of the angle of the thyroid.

Function:  to cover the top of the larynx when you swallow.

The thyroid is fused anteriorly at the midline to form the angle of the thryoid.

Posteriorly:  2 Superior Cornua and 2 smaller Inferior Cornua.

Attachment:  it is attached to the hyoid bone superiorly.

Hyoid:  horseshoe bone (corpus, major horns and minor horns)

Thyroid Notch:  "V" shaped notch on the front of thyroid cartilage.

Anterior Portion:  the arch:  cricoiod arch

Posterior Portion:  the flat part:  4-sided,posterior quadrate lamina

Bumps:  located at the postero-lateral aspect of the arch.  On the inner surface of the inferior cornua of the thyroid are 2 oval depressions.  The inferior cornu fit over the cricoid so that the roud bumps fit into the oval depressions.  

This forms the Crico-thyroid joint.

Paired catilage.

Tetrahedral in shape.

Base:  there is a cylindrical depression on each base that fits into cylindrical bumps located on the superior border of the posterior quadrate lamina of the cricoid. This forms the crico-arytenoid joint.

Antero-lateral surface:  

*triangular fovea:  depression that is triangular and near the apes (top) of the pyramid

*Elongated pit:  long troth depression that is closer to the base of the antero-lateral surface.

With the cricoid still:  the thryoid will move forward and back. 

This accomplishes stretching the vocal folds out (by means of the cricothyroid muscle).

With the thyroid still:  the cricoid will move up and back, therefore, causing the artyenoids to move up and back; stretching the vocal folds.  

4 movements:

Arytenoids move in a downward, forward, and medial-ward direction...adduction

Arytenoids move in a backward, upward, and lateral direction...abduction

Arytenoids slide medially...adduction

Arytenoids slide laterally...abduction

Thyrovocalis/vocalis(thick...main vibratory mass):

Origin:  IAAT (just below the notch)

Insertion:  runs posteriorly to insert at the vocal process of the arytenoid and anterior one half of the elongated pit

Thyromuscularis/thyroarytenoid (thin muscle):

Origin:  IAAT

Insertion:  runs posteriorly and inserts at the muscular process and posterior one half of the elongated pit.

Vocal Ligament:  

Origin:  IAAT

Insertion:  runs posteriorly to the vocal process of the arytenoid.

Lateral Cricoarytenoid

Paired

Origin:  by broad attachment at the antero-lateral arch of the cricoid

Insertion:  runs posteriorly converging to the muscular process of the arytenoid cartilage.

Upon contraction:  exerts a forward pull on the arytenoids pulling them anteriorly.  The vocal processes will be rotated forward, downward, and together...accomplishing adduction.

Accomplishes the medial slide for adduction.

2 bundles:

*Transverse:  deeper of the 2, not paired

Origin:  all along the postero-lateral angle of one arytenoid from base to apex

Insertion:  runs horizontally to insert of the other arytenoid caritlage postero-lateral from base to apex.

*Oblique:  paired, superficial to transverse

Origin:  each one of the pair originates at teh posterior aspect of the muscular process of one arytenoid

Insertion:  runs obliquely to the posterior aspect of the apex of the other arytenoid.

Muscle of Abduction

Fan shaped muscle that is paired

Origin:  broad attachment on the posterior quadrate lamina of the cricoid.

Insertion:  runs superiorly and laterally to insert on the muscular process of the arytenoid cartilage.

Exerts a posterior pull on the arytenoids, rocking the vocal processes backward upward, and apart...accomplishiing abduction.  

Muscle of abduction only in emergency cases

Accounts for lateral slide movement.

 Simultaneous movement of the posterior and lateral cricoarytenoid results in a vector of the 2 directional pulls.  This accomplishes the lateral slide movement.  

Paired with 2 bundles:

*pars recta:  

origin:  antero-lateral arch of the cricoid

Insertion:  runs straight up to insert on the inner aspect of the thyroid lamina

This muscle will pull the thyroid down

*pars oblique:

origin:  antero-lateral arch of the cricoid

Insertion:  runs obliquely upward and posteriorly to insert on the inferior cornu of the thyroid.  .

This muscle will pull the thyroid forward.  

The cricothyroid tenses and thins the vocal folds.

Everything above these is the supraglottic air column.

Medial portion is the vocal ligament.

Immediately lateral to the vocal ligament is the thyrovocalis which is parallel to the thinner thyromuscularis.  

These are below the ventricular folds and they are made of muscle.  

A.K.A. Ventricular Folds

These are composed of mucous membrane.  Medial margin is called the Ventricular Ligament.

Origin:  triangular fovea of the arytenoid cartilage that is on the antero-lateral surface of the arytenoid cartilage near the apex (the triangular pit)

Insertion:  runs forward to insert on the IAAT just below the notch.

The ventricular folds are above the vocal folds.