Palate

Question 1

How may pairs of pharyngeal arches are there in the embryo?
What arches form the mandibular and maxillary prominences?

Answer 1

• 6 pharyngeal arches
• The first arch forms the mandibular and maxillary prominences

Question 2

What form of epithelium forms in the nasal cavity and the oral cavity?

Answer 2

• Nasal - pseudostratified ciliated columnar
• Oral - stratified squamous

Question 3

What bones form the hard palate?

Answer 3

• Palatine
• Maxillary
• Incisive bones

Question 4

Name the following bones

Answer 4

Question 5

What is the normal level of extension of the soft palate?

Answer 5

Extends just caudal to last maxillary molar teeth in normal dogs

Question 6

List the muscles of the soft palate and their function

Answer 6

• Palatinus - shortens the palate rostrocaudally
• Tensor veli palatini - Stretched the soft palate between the pterygoid bones
• Levator veli palatini - Elevates the caudal soft palate

Question 7

What are the 2 functions of the soft palate during swallowing?

Answer 7

• Stimulation of sensory nerves in the palate are part of the mechanism that triggers swallowing
• Closure of intrapharyngeal opening suring swallowing and vomiting to prevent food entering the nasopharynx and subsequently being aspirated

Question 8

What side do unilateral cleft lips most commony form?

Answer 8

Left

Question 9

At what time in foetal development does an insult need to occur to result in a palatal defect?

Answer 9

between day 25-28 in dogs

Question 10

List some basic principles of surgical correction of palate defects

Answer 10

• 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

Question 11

What is the standard closure technique for a:
- Congenital hard palate defect
- Traumatic hard palate “split” as with highrise syndrome
- Soft palate midline cleft

Answer 11

• Congenital hard palate - Overlapping flap
• Traumatic highrise syndrome - Medially positioned flap
• Soft palate - medially positioned flap

Question 12

Name this flap

Answer 12

Overlapping flap

Question 13

Name this flap

Answer 13

Medially-positioned flap

Question 14

List options for surgical correction of congenital hypoplasia of the soft palate

Answer 14

• Bilateral tonsillectomy and extension
• Bilateral buccal mucosal flaps (one rotated, one rotated and overlapped)
• Bilateral pharyngeal advancement flaps and one overlapping hard palate flap

Question 15

How do you repair an oronasal fistula?

Answer 15

Labial-based mucoperiosteal flap

Question 16

How can you close a large caudal hard palate defect?

Answer 16

Split palatal U-flap

Question 17

List options for large palatal defects

Answer 17

• 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

Question 18

What % or airway resistance is due to the nose in normal dogs?

Answer 18

80%

Question 19

What is Poiseuille’s law?

Answer 19

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

Question 20

What is the Hering-Breuer reflex?

Answer 20

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

Question 21

What functional disorders may also contribute to BOAS?

Answer 21

• Fibrosis of the pharyngeal dilator muscles
• Pharyngeal collapse

Question 22

What % of dogs with BOAS have moderate to severe GI signs?

Answer 22

10-74%

Question 23

What is the normal tracheal diameter?

Answer 23

20% of thoracic inlet

Question 24

What should be given before or at induction for upper airway exam?

Answer 24

Anticholinergic to minimise risk of severe bradycardia from vagal discharge during pharyngoscopy

Question 25

What setting should be used for CO2 laser staphylectomy?

Answer 25

- 5-6W - Continuous mode

Question 26

What is the prognosis following soft palate resection?

Answer 26

Good to excellent in 90% Persistent or recurrent signs should prompt a skull CT and retroflexed nasopharyngeal endoscopy to assess for nasopharyngeal turbinates