Flashcards in Surgical conditions of the larynx, gutteral pouches and trachea Deck (109)
What is the primary function of the larynx?
conduit between pharynx and trachea
What are the cartilages of the larynx?
4. arytenoid (x2)
what is the only part of the arytenoid cartilage can you see when looking down the nose?
Why can you not see the muscular and vocal process of the arytenoid cartilage from going down the nose? what is the significance?
they are extraluminal
they have to be accessed from outside
Why is it important to understand the larynx is made up of different parts?
1. can use them as landmarks for surgery access
2. can take pieces off
Why is it important to understand that the epiglottis is bumpy, there are small dorsal vessels?
If you don't see this then likely it is entrapped
Is the notch of the cricoid artilage constant between horses or variable?
Why is important when performing a tie back that the dorsal suture is as close to midline as possible?
so your tie back causes the fold to go up and out instead of just laterally
what is the important muscles of larynx to know (principle abductors)
1. circoarytenoideus dorsalis (CAD)
2. arytenoid transversus
Why is it common to get left laryngeal hemiplasia
the left recurrent laryngeal nerve travels much farther
it is a dying back so get left sided hemiplasia first
extravasation of irritant substances
extravasation of irritant substances (e.g. phenylbutasone)
What is the innervation of the principles abductors?
1. recurrent laryngeal nerve (right loops around the subclavian artery)
2. left loops around liagmentum arteriosum
3. superior laryngeal nerve (cricothyroideus m (vocal cords))
What does the hypoglossal nerve innervate?
the hyoepiglottis muscle (cranial nervee 12)
What does the hyoepiglottis muscle do?
it prevents the epiglottis from dancing in the wind
How do you palpate cricoarytenoideus dorsalis atrophy
by palpating top of the larynx (it passes over the muscular process)
When you have left laryngeal hemiplasia (not tight) what does the vocal cord and saccule look like? What does the size of the lumen look like?
the vocal cord is not tight--further catches air
the saccule is baggy
the lumen is smaller
What impedes airflow into the trachea with left laryngeal hemiplasia?
1. collapsed cartilage--smaller lumen
2. vocal cords catching air
What is the significance of epiglottic entrapment?
entrapped in aryepiglottic membrane
What is the history/exam of epiglottic entrapment?
respiratory noise (inspiratory and expiratory)
nasal discharge and coughing--coughing because feel something on the soft palate--mucosal membrane produces more fluid=nasal discharge. trying to swallow to get the blob back in place
What is the pathogenesis of epiglottic entrapment?
the loose mucosa of the epiglottis gets pulled tight on the underside of the epiglottis, and it is pulled up to the end of the epiglottis like taking off a shirt and you cannot see the cranulated/vessely surface of the epiglottis. it is NOT dorsal displacement because you can see a structure. if you get over the blob of tissue then you can see the epiglottis disappearning into the blob
Why is there inspiratory and expiratory obstruction with epiglottic entrapment
There is a big block on inhalation, also catches air on expiration
How is epiglottic entrapment diagnosed?
endoscopy: serrated border
dorsal vascular pattern
may be INTERMITTENT or PERSISTENT
can see the aryepiglottic fold coming
get hypoplastic epiglottis with epiglottic entrapment?
because they are being squashed down
Why might epiglottic entrapment have ulceration?
it is irritated and rubbing on the underside of soft palate
What is the treatment for epiglottic entrapment?
tissue sparing technique
1. laser axial division
2. transoral axial diversion (bistoury)
3. transnasal axial division (bistoury)
4. surgical excision via laryngotomy
What are horses at risk for after epiglottic entrapment treatment?
dorsal displacement of the the soft palate (even though not touching anything else besides epiglottis)! WARN CLIENTS
Why is it important to use a tissue sparing technique for epiglottic entrapment treatment?
because there is a reason there is so much mucosa on the epiglottis! it is needed for keeping the epiglottis loose. if take too much can scar and cause epiglottis to be stuck in mouth (dorsal displacement of soft palate)
What is an issue with transnasal axial division for doing surgery of epiglottic entapment?
as soon as touch epiglottis the horse swallows. want to cut the epiglottis and instead it pops down and you can cut the soft palate or have epiglottic/pharyngeal lacerations
If the epiglottis is very thick and ulcerated what method of surgery to treat epiglottic entrapment is used?
inside the larynx. put forceps into larynx, retroflex epiglottis and cut off tissue
But everything is upside down!!!
Very important to know anatomy
Careful not to create dorsal displacemnet