Chapter 46 - Larynx Flashcards
Larynx - the CAD is the major abductor or adductor muscle?
Abductor - it widens the laryngeal aperture
What are the muscles responsible for adduction of the larynx?
arytenoideus transverse muscle
What are the muscles responsible for adduction of the larynx?
1) arytenoideus transversus m.
2) thyroarytenoideus m.
3) cricoarytenoideus lateralis CAL
What is the main function of the crycothyroideus?
tenses vocal chords during vocalization)
Thyroid, cricoid and arytenoid are what type of cartilage?
Hyaline
Name the extrinsic muscles of the larynx
1) Cricopharyngeus
2) Thyrophayngeus
3) Thyrohyoideus
4) Sternothyroideus
5) Hyoepiglotticus
What is the nerve supply to the larynx?
Recurrent laryngeal nerve (branch of the vagus X)
cranial laryngeal nerve also branch of vagus (cricothyroideus vocalization)
What is the blood supply to the larynx? lymphatics?
caudal laryngeal artery
ascending pharyngeal artery
caudal laryngeal vein
ascending pharyngeal vein
Lymphatics :
- retropharyngeal
- cranial
- deep cervical lymph nodes
Corniculate, epligottis are what type of cartilage?
Elastic
Cricoarytenoid cartilage is which type of joint?
diarthrodial joints that allow
the arytenoid cartilages to rotate dorsolaterally during abduction,
and medially during adduction.
What are the different pathologies of the larynx (total 15)?
- Hemiplegia of the recurrent laryngeal nerve
- Vocal cord collapse
- Bilateral laryngeal collapse
- Right-sided laryngeal hemiplegia
- Cricopharyngeal-laryngeal dysplasia (4BAD)
- Collapse apex corniculate process
- Medial deviation of the aryepiglottic folds
- Arytenoid chondropathy
- Epiglotic entrapment
- Acute epiglotittis
- Subepiglotic cysts
- Dorsal epiglottic abcess
- Subepiglotic granuloma
- Epiglottic hypoplasia, flaccidity deformity
- Epiglottic retroversion
Laryngeal mucosa has sensory mechanoreceptors that detect which different stimuli (4 types)
transmural pressure changes,
airflow,
temperature,
and laryngeal motion
What are possible causes of damage to recurrent laryngeal nerve?
95% idiopathic some have cause
perivascular jugular vein
GP mycosis
trauma injuries in the neck
strangles abcessation
impingement by neoplasm
organophosphate toxicity
pant poisening
hepatic encephalopathy
Loss of large mylinated axons in left recurent laryngeal nerve. What type of fibers are lost?
Type 2
What is the % of muscle loss prior to clinical signs for left recurrent laryngeal nerve?
75%
What type of horses are predisposed RLN?
Larger breeds and younger horses (2-3 yold TB 2-8%) and draught horses (35%)
What are the methods of diagnosis of RLN?
history
physical exam
poor performance and inspiratory noise at work
palpable atrophy of the left CAD
Definitive dx made by endoscopy and gold standard is dynamic endoscopy
Describe grade I/IV of Havemeyer grade
All arytenoid cartilages movements are synchronus and symetric and full arytenoid cartilage abduction is achieved and maintained
Describe grade II.A
II Arytenoid cartilage movements are and asynchronous and/or larynx is asymmetric at times but full artyenoid cartilage abduction can be achieved and maintaned
A. Transient asynchronus, flutter, or delayed movements seen
Describe grade II B
Arytenoid cartilage movements asynchronous and/or asymetric at times but full arytenoid abduction is achieved and maintained
B. There is asymtry of the rima glottis due to lack of mobility of the affected arytenoid cartilage and vocal fold, but there are occasions typically after swallowing or nasal occlusion when full asymmetrical abduction is acheived and maintained.
Describe grade III A
Arytenoid cartilage movements are asynchronous and asymetric and full arytenoid cartilage abduction cannot be achieved and maintained
A. There is asymetry of the rima glottis much of the time due to lack of mobility of the arytenoid cartilage and vocal fold, but there are occasions typically after swallowing or nasal occlusion, when full symmetrical abduction is achieved but not maintained
Describe grade III B
There is obvious arytenoid abductor muscle deficit and arytenoid cartilage asymetry. Full abduction is never achieved.
Describe grade III C
There is marked but not total arytenoid abductor muscle deficit and arytenoid cartilage asymmetry with little arytenoid cartilage movement. Full abduction is never achieved.
Grade IV
complete immobility of the arytenoid cartilage and vocal fold