Larynx Flashcards
List the cartilages of the larynx
- Epiglottic
- Thyroid
- Cricoid
- sesamoid
- interarytenoid
- paired arytenoid
List the processes of the arytenoid cartilages
- Cuneiform
- Corniculate
- Vocal
- Muscular
List the extrinsic and intrinsic muscles of the larynx
Extrinsic (constrict the caudal part of the pharynx)
- Thyropharyngeus
- Cricopharyngeus
Intrinsic
- Cricoarytenoideus dorsalis (arytenois abduction)
- Cricoarytenoideus lateralis (Pivots arytenoid inwards to close rima glottidis
- Thyroarytenoideus - Gives rise to ventricularis and vocalis muscles
- Arytenoideus transversus
- Hyoepiglotticus (draws epiglottis downwards)
- Cricothyroideus (tenses the vocal cords)
How does the feline laryngeal anatomy differ from dogs?
- The arytenoid cartilages lack a cuneiform and corniculate process and try aryepiglottic folds are absent (mucosa connects sides of epiglottis directly to the cricoid lamina)
- Vocal cords are thick and rounded
- Ventricles are absent
List the three functions of the larynx
- Larynx is pulled cranially during swallowing to block laryngeal opening
- Controls airway resistance
- Voice production
What % of dogs with BOAS will have:
- Stenotic nares
- Elongated soft palate
- Everted saccules
- Laryngeal collapse
- Stenotic nares 43-85%
- Elongated soft palate 86-96%
- Everted saccules 55-66%
- Laryngeal collapse 8-70%
What are the three stages of laryngeal collapse?
- Stage I - Everted laryngeal saccules
- Stage II - Cuneiform process losses its rigidity and becomes medially displaced
- Stage III - Corniculate process collapse, resulting in loss of dorsal arch of rima glottidis
What are the options for a patient with laryngeal collapse who does not respond to surgical management of BOAS and medical management?
- Permanent tracheostomy
- Laryngeal tieback
Damage to what structures can cause lar par?
- Nucleus ambiguus
- Vagus nerve or its branches
- Cricoarytenoideus dorsalis muscle
What causes congenital lar par?
What breeds are overrepresented?
- Progressive degeneration of neurons within the nucleus ambiguus and Wallerian degeneration of laryngeal nerves
- Bouvier des Flandres, Bull terriers, dalmations, Rottweilers, Leonberger
What breeds are overrepresented for acquired lar par?
- Lab and Golder Retrievers
- St Bernards
- Irish Setters
What % of dogs with lar par have pre-op aspiration pneumonia?
Oesophageal dysfunction?
- Aspiration pneumonia 7.9%
- Oesophageal dysfunction 11.4% - assoc with an increased risk of post-op complications
What is doxapram?
CNS stimulant which causes an increased resp rate and tidal volume by increasing the electrical activity in the inspiratory and expiratory centers of the medulla
What are the surgical options for the Tx of lar par?
- Unilateral or bilateral arytenoid lateralisation
- Ventricular cordectomy and partial arytenoidectomy
- Modified castellated laryngofissure
- Permanent tracheostomy
What is the reported increase in rima glottidis opening using cricoarytenoid and thyroarytenoid lateralisation?
- Cricoarytenoid - 207%
- Thyroarytenoid - 140%