Ch 100 - Palate Flashcards
How may pairs of pharyngeal arches are there in the embryo?
What arches form the mandibular and maxillary prominences?
- 6 pharyngeal arches
- The first arch forms the mandibular and maxillary prominences
What form of epithelium forms in the nasal cavity and the oral cavity?
- Nasal - pseudostratified ciliated columnar
- Oral - stratified squamous
What bones form the hard palate?
- Palatine
- Maxillary
- Incisive bones
Name the following bones
What is the normal level of extension of the soft palate?
Extends just caudal to last maxillary molar teeth in normal dogs
List the muscles of the soft palate and their function
- Palatinus - shortens the palate rostrocaudally
- Tensor veli palatini - Stretched the soft palate between the pterygoid bones
- Levator veli palatini - Elevates the caudal soft palate
What are the 2 functions of the soft palate during swallowing?
- Stimulation of sensory nerves in the palate are part of the mechanism that triggers swallowing
- Closure of intrapharyngeal opening during swallowing and vomiting to prevent food entering the nasopharynx and subsequently being aspirated
What side do unilateral cleft lips most commony form?
Left
At what time in foetal development does an insult need to occur to result in a palatal defect?
between day 25-28 in dogs
List some basic principles of surgical correction of palate defects
- Teeth at the surgical site or those which could damage the repair are removed 6-8 weeks prior to definitive repair
- Laser, electrosurgical and radiosurgical devices not used for haemostasis
- Flap should be at least 1.5x as wide as the defect they are going to cover
- 2-layer closure
- Suture lines preferable not overlying a void
- Injured tissue left to fully declare itself prior to repair
What is the standard closure technique for a:
- Congenital hard palate defect
- Traumatic hard palate “split” as with highrise syndrome
- Soft palate midline cleft
- Congenital hard palate - Overlapping flap
- Traumatic highrise syndrome - Medially positioned flap
- Soft palate - medially positioned flap
Name this flap
Overlapping flap
Name this flap
Medially-positioned flap
List options for surgical correction of congenital hypoplasia of the soft palate
- Bilateral tonsillectomy and extension
- Bilateral buccal mucosal flaps (one rotated, one rotated and overlapped)
- Bilateral pharyngeal advancement flaps and one overlapping hard palate flap
How do you repair an oronasal fistula?
Labial-based mucoperiosteal flap
How can you close a large caudal hard palate defect?
Split palatal U-flap
List options for large palatal defects
- Removal of teeth 6-8 weeks prior
- Local axial pattern flaps (based on major palatine and infraorbital arteries)
- Distant axial pattern flaps (angularis oris, caudal auricular, superifical temporal etc)
- Tongue flap
- Grafting of auricular cartilage
- Corticocancellous tibial bone
- Myoperitoneal microvascular flaps
- Prostheses
What % or airway resistance is due to the nose in normal dogs?
80%
What is Poiseuille’s law?
Q = pie(pressure difference)(r^4)/8nl
Q - rate of flow
r - radius
n - viscosity of the gas
l - length of airway
Flow is proportional to radius to the fourth power
What is the Hering-Breuer reflex?
A stretch reflex mediated by vagal fibres that control the rate and depth of respiration.
Causes a longer contraction of the inspiratory muscles during each breath cycle in response to increased upper airway resistance
What functional disorders may also contribute to BOAS?
- Fibrosis of the pharyngeal dilator muscles
- Pharyngeal collapse
What % of dogs with BOAS have moderate to severe GI signs?
10-74%
What is the normal tracheal diameter?
20% of thoracic inlet
What should be given before or at induction for upper airway exam?
Anticholinergic to minimise risk of severe bradycardia from vagal discharge during pharyngoscopy
What setting should be used for CO2 laser staphylectomy?
- 5-6W
- Continuous mode
What is the prognosis following soft palate resection?
Good to excellent in 90%
Persistent or recurrent signs should prompt a skull CT and retroflexed nasopharyngeal endoscopy to assess for nasopharyngeal turbinates
