Phonatory System Anatomy- Intrinsic Laryngeal Muscles

What roles do intrinsic muscles play?

Change: VF postion (abducted vs adducted vocal folds), glottis size (increased or decrease space between vocal folds) and vf legnth (short vs long) and tension

What are the tensor muscles

Thyroarytenoids
--> a. internal thyroarytenoids
-->b. external thyroartenoids

What muscle changes vocal fold length?

cricothyroids

what is the abductor muscle

posterior cricoarytenoid

what are the adductor muscles

lateral cricoarytenoid

Interarytenoids: transverse arytenoid and oblique arytenoid

what muscle provides airway protection

aryepiglottic

internal thryoarytenoid (green)

closer to midline- deeper
- also vocalis
- also thyrovocalis

External thyroarytenoids (red)

Also thyromuscularis

Anterior view of thryoarytenoids- relative to where the vocal folds and other cartilages would be located

Internal thyroarytenoids attachments

thyroid (top), vocal process of arytenoid (white lining) vocal ligament (bottom)

External thyroarytenoids (lateral border)

Thyroarytenoids- superior view with attachments removed

The thyroarytenoids muscles comprise _____ of vfs

bulk esp. the internal thyroarytenoid

Both thyroarytenoids have the same functions what are they? (both parts in green)

tense vfs
relax vfs
shorten vfs

What are the two parts of the cricothyroids?

Pars Recta (top- runs more straight and down)
Pars oblique (bottom-runs at an angle)

cricothyroids attachments

Cricoids (anterolateral border)- bottom arrow

thyroid- top arrow

cricothyroids function (both have the same function)

lengthen vfs

what is the result of the cricothyroids lengthening the vfs

thin and stiffen vfs

How do the cricothyroids thin and stiffen vfs

- when contracts = tips thyroid cartilage forward and cricoid tilts back which will in turn tilt arytenoids back

- when cricothyroids contract, distance between thyroid & crioid... and thus arytenoids (that sit on superior posterior border of the cricoid) increase. See 10:54 of ELC video

result of vfs lengthened, thinned and stiffened

higher pitch

a little analogy to understand cricothyroid effect on vfs- Biceps

Lengthen muscle --> appears thinner and stiffer

shorten muscle--> appears thicker and floppy

posterior cricoarytenoid

abducts vocal folds

posterior cricoarytenoid located

cricoid (posterior side)

posterior cricoarytenoid attachments

cricoid (posterior side) - left arrow

muscular process of arytenoid (right arrow)

muscular process of arytenoid: Why is it called muscular process?

A lot of muscular converge on that process of the arytenoid

posterior cricoarytenoid functions: function 1

- abduct vfs (from contracting)

- used during speech for: voiceless sounds: /p/, /s/, /ch/

why do we want the vfs to abduct during voiceless sounds?

so the exhaled airstream wont cause the vfs to vibrate

posterior cricoarytenoid functions: function 2 (watch 20:49 of video for visuals)

- abduct vfs

- used for inhalation, esp deep one bc we want to get greater volume and air in (remember during inhalation muscles contract)

where is the lateral cricoarytenoid located? (in green)

lateral border of cricoid

lateral cricoarytenoid attachments

lateral border of crcoid (top arrow)
muscular process of arytenoid (bottom arrow)

lateral cricoarytenoid function

adduct vfs (when it contracts)

Interarytenoids (transverse and oblique)

oblique arytenoids attachments

muscular process of one arytenoid (left arrow) to apex of other arytenoid(right arrow)

--- criss-cross pattern.

How is the transverse arytenoid unique?- deep to oblique arytenoid

- unpaired muscle

transverse arytenoid attachments

lateral border of one arytenoid
lateral border of other arytenoid

interarytenoid functions together

adduct vfs- pull apart two vocal processes of each arytenoid together as well- effectively closing off the entire glottis

aryepiglottic muscle

deflects epiglottis over airway opening to help protect the airway during swallowing

aryepiglottic muscle location

lateral walls of supraglottal cavity (supraglottal cavity is the space above the glottis)

aryepiglottic muscle function

pull epiglottis down
cover/protect airway (over the top of the trachea)