L2: Larynx & Trachea

what is the dorsal edge of the epiglottis?

-aditus laryngis

summary:

vestibule

-entrance of larynx to vocal folds

human anatomy:

vocal chords

-vocal folds in animals

in relation to the rima glottidis where does the infraglottic cavity sit?

-ventral/caudal to rima

what happens to cats when you place a tube?

-vocal folds spasm and collapse, larynx closes

-can spray to numb them

-or, put something before placing tube (like a needle) to prevent collapse

generally, how do extrinsic mm attach?

-cartilage to cartilage

extrinsic mm:

hyoid bones

-short

larynx → hyoid

extrinsic mm:

pharynx

-chin mm

-chin forward, pull larynx forward

extrinsic mm:

sternum

-pull larynx backwards

general attachment:

thyrohyoid m

thyroid → hyoid

general attachment:

hyoepiglottic m

hyoid - epiglottis (forward, relaxed) → open

general attachment:

geniohyoid m

chin → hyoid

-not directly attached to larynx

fx:

sternothyroid m

(w/ sternohyoid, omohyoid (horses))

-move larynx caudally (open)

-rostrally will close

descended larynx (human)

-choking hazard

-but caused phonation with increased hollow space

-as the SC straightens, base of skull stays short but top gets bigger

• larynx descends with them

which m does not attach to the arytenoids?

-cricothyroid m

what mm control the vocal folds? (general attachment)

-mm that attach to arytenoids

what is the ONLY vocal fold abductor?

-dorsal cricoarytenoid m

attachments:

dorsal cricoarytenoid m

dorsal cricoid → m process of arytenoid

fx:

dorsal cricoarytenoid m

abducts ventral edge arytenoid

-tenses vocal folds

-draw vocal fold laterally

(4) vocal fold adductor mm

cricothyroid m

lateral cricoarytenoid m

transverse arytenoid m

thyroarytenoid m

which is the only larynx m that is innervated by the external cranial laryngeal n?

-cricothyroid m

what are the 2 nn that branch off vagus nn (innervate larynx)

-caudal laryngeal

-cranial laryngeal

what is the purpose of the internal cranial laryngeal n?

-sensory to mucosa (aka if you something goes down into larynx you can start coughing)

what does damage to the caudal laryngeal n cause?

roaring (eq)

how to tell if you are placing a tube properly in horses?

-if going into trachea should see tube moving under the horse’s neck skin

tracheal microanatomy (in order)

1 - mucosa

2 - LP

3 - submucosa

4 - musculocartilagenous layer

5 - adventitia

what is unique about the seromucous tracheal glands?

-produce a fluid between sticky mucous and v thin serous fluid

-fx to provide lubrication and moisten epithelium