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Larynx: Thurs, Oct. 12


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Larynx: intro
*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
1. corniculate-pinched off portion of arytenoid cartilage, but considered a separate cartilage
2. cuneiform-lies along aryepiglottic fold
3. arytenoid cartilage
Thyrohyoid memebrane:
*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
1. pear/leaf-shaped, elastic cartilage, doesn't ossify
2. attached to thyroid cartilage inferiorly and tongue superiorly through glossoepiglottic folds
3 paired cartilages:
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
Vocal folds:
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
Spaces between vocal folds:
1. Rima glottidis: space between 2 vocal folds on either side
2. rima vestibuli: space between 2 vestibular folds
3 parts of laryngeal cavity:
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
Muscles: Extrinsic
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
Intrinsic muscles:
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
Nerve and Arterial supplies:
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

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

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