Larynx: Thurs, Oct. 12

Front 1

Larynx: intro

Back 1

*voice-box
*located superior part of respiratory tree, superior to trachea
**functions: valave to prevent foreign objecdts form entering the respiratory tree
**modified to produce sound, not speech

1. piriform recess: where "fishbone" gets caught and neoplasms develop; internal laryngeal nerve (sensory) is covered by mucosal fold in recess
2. Aditus: opening of larynx; comprised of a) epiglottis, b) aryepiglottic fold, c) arytenoid cartilage

**CC: when eating, bolus of food ispushed back from oral cavity. larynx ascend, and bolus pushes epiglottis over aditus to close it off. aryepiglottic folds are brought together

Front 2

Cartilages:

Back 2

1. corniculate-pinched off portion of arytenoid cartilage, but considered a separate cartilage
2. cuneiform-lies along aryepiglottic fold
3. arytenoid cartilage

Front 3

Thyrohyoid memebrane:

Back 3

*attahces hyoid bone to thyroid cartilage
*pierced by internal laryngeal nerve and superior laryngeal artery

**hyoid bone has a body and 2 projections: lesser horn extending superiorly and greater horn

Front 4

3 unpaired cartilages:
Thyroid

Back 4

1. superior and inferior horns
2. lamina (2)-which meet anteriorly @ laryngeal prominence "Adam's apple"
3. lies @ C4-C5
4. hyaline cartilage
5. acute angle between angle in lamina is ~90 deg in male, and 120 in females
6. greek for shield
7. oblique line for attachment of sternothyroid and thyrohyoid muscles
8. inferior horn articulates with cricoid cartilage
9. A-P length doubles @ puberty

Front 5

Cricoid:

Back 5

1. located @ C6
2. hyaline cartilage
3. only cartilage that forms a complete circular ring
**CC: trauma patient, push cricoid cartilage posteriorly to prevent vomit from going down larynx and stop vomit from going superiorly through esophagus
3. arch anteriorly
4. lamina, enlarged portion, posteriorly
5. articulates with arytenoid cartilage and inferior horn of thyroid cartilage

Front 6

Epiglottis:

Back 6

1. pear/leaf-shaped, elastic cartilage, doesn't ossify
2. attached to thyroid cartilage inferiorly and tongue superiorly through glossoepiglottic folds

Front 7

3 paired cartilages:

Back 7

1. cuneiform: elastic, club-shaped
*lies in area of epiglottic fold and does not contact other cartilages

2. corniculate: elastic cartilage perched on top of arytenoid

3. arytenoid: pyramid shaped, hyaline cartilage attached by base on cricoid cartilage
*3 processes: superior (extends to apex), muscular (muscles attach), vocal (vocal ligament attaches)
*medial surface is only surface muscles don't attach
*slide back and forth across, laterally, medially, and horizontally/back and forth in AP direction/ also rotates
*much movement needed b/c intrinsic muscles attached here/influence speech

**muscles arise from superior part of cricoid arch and posterior part of cricoid lamina

Front 8

Vocal folds:

Back 8

2 vocal folds:

1. true folds: inferior
2. vestibular, or false, folds
3. ventricle: space between true and false folds
*sometimes ventricle enlarged to form sacule, which is "oil can of larynx"-sebaceous glands line mucosa of sacule and ventricle

Front 9

Ligamentous and membranous skeleton:

Back 9

1. Quadrangular membrane:
a) submucosal sheet of connective tissue
b) free inferior margin is vestibular fold
c) free superior margin is aryepiglottic fold
d) inferior extent is vestibular ligament and superior extent is aryepiglottic fold
e) cuneiform cartilage helps support aryepiglottic fold

2. Conus elasticus: 3 structures
1) cricovocal membrane: ligament extends from superior border of cricoid cartilage up to vocal ligament
2) vocal ligament: runs from vocal process of arythenoid cartilage anterior to thyroid cartilage
3) median cricothyroid ligament: severed in emergency tracheotomy; located between thryoid and cricoid cartilages; @ midline, feel an interval

Front 10

Spaces between vocal folds:

Back 10

1. Rima glottidis: space between 2 vocal folds on either side
2. rima vestibuli: space between 2 vestibular folds

Front 11

3 parts of laryngeal cavity:

Back 11

1. vestibule: lies superior to false folds and is initial portion entered during intubation; mucosa lined with fibers tha t bring cough reflex, true vocal folds close off as reflex mechanism and can't breathe
2. ventricle: between true and false folds; may be enlarged sacule; other primates and glassblowers have enlarged sacules
*vocal fold consists of mucosa, vocal ligament and vocalis muscle; no submucosa, so looks white
3. infraglottic: inferior to true vocal folds

Front 12

Action of vocal folds:

Back 12

1. in intubation, want head extended as far as possible @ AO joint, straight passageway between oro- and naso- pharynx with larynx
2. indirect larygnoscopy: handheld mirror goes down against uvula and light is reflected
3. Quiet respiration: vocal folds adducted or slightly abducted and rima glottidis and vestibule partially open
4. Forced respiration: vocal folds more abducted and rima glottidis and vestibule wide open
5. Recurrent laryngeal nerve damage: vocal fold will close off ipsilarterally; get transient hoarseness and voice fatigue/both nerves damaged: trouble breathing
6. Phonation: vocal folds close together during talking, even closer when whispering
a)discectomy-can cause recurrent laryngeal nerve damage; usually go through carotid sheath
7. effort closure: when trying to blow out, vestibular folds close and air goes out ventricles; vocal folds also close off rima glottidis
*same as when something "goes down the wrong pip"
8. Emergency trach: laryngotomy done between cricoid and thyroid cartilages
9. Permanent trach: pull down isthmus of thyroid up or down and then go through tracheal rings 2-4

Front 13

Muscles: Extrinsic

Back 13

1. suprahyoid muscles:
a) stylohyoid
b) digastrics
c) mylohyoid
d) geniohyoid

*suprahyoids elevate larynx adn trachea, important in 1st phase of swallowing (voluntary); pull on hyoid, which attaches to thyroid cartilage

2. infrahyoids: strap muscles

*infrahyoid muscles depress larynx and trachea-happens when sing a low note

Front 14

Intrinsic muscles:

Back 14

1. posterior cricoarytenoid:
a) arises from posterior surface cricoid carilage lamina
b) attaches to muscular process arytenoid cartilages
c) abducts vocal folds, important in strong respiration (*could be most important muscle in body)

2. Lateral cricoarytenoid:
a) chief antagonist of posterior cricoarytenoid
b) arises from superior part of arch and some lamina and extends back to muscular process
c) adducts vocal folds

Sphincters of rima glottidis and aditus:
1. Inner arytenoidus:
a) runs between one arytenoids cartilage to another
b) only unpaired muscle of larynx
c) contraction brings arytenoids cartilages together
d) transverse filbers are deeper than oblique
e) obliques fibers run from muscular process of arytenoid cartilage to apex of other; bring together
f) oblique fibers continue and form a substance of aryepiglottic fold called aryepiglotticus-usually not well developed but contractions pulls epiglottis back
**transverse and oblique arytenoidus pull vocal folds together. also, oblique fibers pull epiglottis posteriorly

2. cricothyroidL tensor of vocal cord
b) inserts into inferior horn and inferior border of thyroid cartilage
c) pulls thyroid cartilage down and tenses or lengthens vocal ligament

3. Thyroarytenoideus:
a) antagonist of cricothyroid, so relaxes vocal ligament
b) runs from posterior aspect of thyroid cartilage to arytenoid cartilage
c) most medial fibers make up vocalis muscle

3. vocalis: inserts and arises along the entire length of vocal ligament; used in whispering

Front 15

Nerve and Arterial supplies:

Back 15

nerves:
1. external laryngeal: branch of superior laryngeal; supplies part of inferior constrictor muscle and cricothyroid muscles
2. internal laryngeal: branch of superior laryngeal; main sensory nerve of larynx
3. recurrent laryngeal: all otehr intrinsic muscles (except cricothyroid)
*runs posterior to cricothyroid joint and is then called inferior laryngeal nerve and it divides into anterior and posterior branches

Arteries:
For Pharynx:
1. ascending pharyngeal
2. ascending palatine branch of facial
3. superior thryoid
4. inferior thyroid
For Larynx:
1. superior laryngeal branch of superior thyroid-which pierces the thyrohyoid membrane (sometimes comes off ECA instead of superior thyroid)
2. inferior laryngeal, which comes off inferior inferior thyroid