88 - Salivary Glands Flashcards
Major salivary glands
Parotid
Mandibular
Sublingual
Zygomatic
Minor salivary glans
Tonsillar
Labial
Lingual
Molar
Palatine
Buccal
Molar in cats only - Well developed
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6 functions of saliva
- Lubricate bolus
- Thermoregulation
- Oral cavity cleansing
- Buffer weak acids
- Protect the epithelium
- Reduce bacterial growth
Salivary amylase plays no significant role in digestion in dogs and cats
How is saliva produced and transported from the gland?
Produced in acinus
Serous and mucin producing cells
Flows into intercalated duct which coalesce
Intralobular => Interlobular => Lobular => Lobar => Major excretory duct
Mandibular and parotid mainly serous
Zygomatic and sublingual mainly mucinous
How is saliva processed before excretion?
Phase one =
* Produced in acinus
* Acinar cells absorb Na+
* Water drawn in creating Na rich saliva
* Flows into collecting ducts
Phase two =
* Active resorption of Na
* Secretion of Bicarb and Potassium within the intralobular duct epithelium
* Resultant saliva is Bicarb and Potassium rich
How is saliva production mediated?
Autonomic control
Parasympathetic stimulation
- vasodilation
- upregulation of cyclic guanosine monophosphate (cGMP) which directly upregulates acinar production of saliva
Sympathetic downregulation
- Minor inhibition of flow by causing contraction of myoepithelial cells
Which nerves provide parasympathetic supply to the salivary glands?
FACIAL NERVE
MANDIBULAR NERVE
Mandibular n = largest branch of the trigmeminal
Which structures surround the parotid salivary gland?
(Muscular, neural, vascular?)
Caudally:
* Sternomastoid m
* Cleidocervicalis m
Cranial:
* Masseter m
Ventral:
* Mandibular salivary gland
Superficial:
* Platysma
* Parotidoauricularis
Deep:
* Auricular cartilage of ear
Neurovascular
* Facial nerve
* Maxillary and temporal arteries
* Internal maxillary vein
CHALLENGING DISSECTION
Where does the parotid duct travel?
Where is the papilla?
2-3 ductules exit
Ventrorostral to the gland
Lateral and ventral to masseter
Papilla = 4th Upper Premolar (Carnassial tooth)
Accessory gland is dorsal to the duct and empties into main duct
Blood supply to the parotid?
Parotid a
=> Branch of the external carotid
(Sits medial to the gland, ventral to ear canal)
Venous drainage =>
Greater auricular and temporal veins
Where is the zygomatic gland located?
How many ducts are there?
Where is the major papilla for the zygomatic duct?
Located ventral and rostrolateral to the globe
1 major and 4 minor ducts
Enters the vestibule 1cm caudal to the parotid papilla at the level of the last upper molar
What is the blood supply to the zygomatic salivary gland?
Infraorbital artery
Deep facial vein
Where does the mandibular salivary gland sit?
Which structures surround it?
Sits caudomedial to the angle of the mandible
Gland lies medial to the linguofacial and maxillary vein junction (External Jugular bifurcation)
Mandibular LN ventral to the gland
Medial retropharyngeal and larynx medial to the gland
How is the mandibular salivary gland related to the sublingual gland?
Shares a common capsule
forms the
‘Mandibular sublingual salivary gland complex’
Where does the mandibular salivary duct run?
Where does the papilla sit?
Exits medial surface of the gland
Runs medial to the sublingual gland
Horizontal to mandibular ramus
Runs between the styloglossus and myelohyoideus muscles
Enters at the sublingual caruncle
(lateral to the frenulum)
What is the blood supply to the mandibular salivary gland
Glandular branch of the facial a.
Lingual vein
What are the two portions of the sublingual gland?
Monostomatic
- Shared capsule with the mandibular gland
- Tapers to triangular shape rostrally
- Loose clusters sitting deep to the digastricus and myelohyoideus
Polystomatic
- Small clusters ROSTRAL to the LINGUAL NERVE
- Empty directly into the oral cavity
Where doe the sublingual duct enter the oral cavity
At the sublingual caruncle
Just caudal to the mandibular papilla
Note the duct courses with the mandibular duct, but they are seperate
Blood supply for the sublingual?
Glandular branch of the facial artery
(Monostomatic portion as part of MDSLGC)
Sublingual branch of the lingual artery
(Polystomatic portion)
Venous drainage = satellites of the arterial supply
What is the most common type of sialocoele?
How do they present?
Cervical
Cranioventral cervical swelling
(Can be difficult to differential which side)
Presenting signs for pharyngeal sialocoele?
Which breed are over-represented for these?
Swelling caudal, dorsal or lateral
Stridor or respiratory distress
Miniature poodles
(Males > Females)
Presenting signs for sublingual sialocoeles?
RANULA
Medial tongue deviation
Dysphagia, difficulty with prehension
Describe the surgical technique for Zygomatic Sialoadenectomy
- Approach to the dorsal zygomatic arch
- Reflection of the masseter aponeurosis from ventral arch
- Reflection of orbital fascia from dorsal arch
- Zygomatic ostectomy
- Blunt dissection of the gland
- Dorsal retraction to visualise and ligate infraortbital a blood supply
Describe the approach for parotid sialoadenectomy
Common complication?
- Incision from ventral to acoustic meatus to caudal mandible
- Skin, subcut, platysma, parotidoauricularis incised
- Identification and division of caudal auricular vein
- Gland dissected at dorsocranial border and continued rostrally to visulise ear canal
- Care to spare the facial nerve at the level of the horizontal ear canal
- Cauterise small medial vessels during dissection
- Dissected out to level of the duct, ligated and divided.
- Check lateral cheek swelling may be due to accessory parotid gland involvement
- Minimise deadspace through closure of superficial muscles, subcut and skin
Facial nerve paresis
Describe the surgical treatment for ranulas
Mandibular and sublingual sialoadenectomy
Plus MARSUPIALISATION
- Large oval shpaed full thickness region of the ranula excised
- External oral mucosa sutured to the sialocoele lining
- Mucosal margin can be hemmed inwards to prevent exposed edges healing over
Describe the ventral approach for mandibular and sublingual sialoadenectomy
Incision =
* 4-5cm to caudal to margin of mandibular ramus
* Extending rostrally towards mandibular physis
* Midline if bilateral needed
* Incision through subcut, skin and platysma
Identification =
* Identify jugular bifurcation (maxillary and linguofacial veins)
* Mandibular gland immediately cranial to bifurcation (mandibular LN ventral and retropharyngeal medial to it)
* Capsule exposed with blunt dissection and incised
* Medial vessels ligated
* Complex caudally retracted to allow dissection of sublingual gland dorsal to digastricus
* Haemostat placed from rostral to caudal under the digastricus
* Duct clamped and transected to remove gland complex
* Ducts pulled under the digastricus and dissection continued rostrally
* Mylohyoideus incised for rostral exposure if needed
* CONTINUE DISSECTION TO THE LEVEL OF THE LINGUAL NERVE
* If ranula present, dissect to level of sublingual caruncle
Lingual nerve = end of the monostomatic complex
Remaining should drain into oral cavity directly
Describe the lateral approach to the mandibular/sublingual gland complex
Lateral recumbency, affected side up, neck extended
- Jugular bifurcation identified
- Horizontal incision over mandibular gland between linguofacial and maxillary vein
- Capsule exposed bluntly, incised and emptied of mucocoele
- Blood supply ligated and dissection continued rostrally parallel with ducts
- Ducts ligated or separated with slow/steady traction
- Transected ends accessed medially and rostrally to the digastricus and dissectio continued
