Chapter 88 Salivary Glands Flashcards
What method can be used to improve visualisation of parotid salivary gland intra op
Injection of new methylene blue
(0.25 ml in 3 ml of 0.9% saline, inject 1.5-3ml diirectly or via parotid duct - Gordo, JSAP, 2020)
Name a non-sx treatment option described for sialocoele
Injection of N-acetylcysteine
(10% solution injected via duct until retrograde flow seen)
22% recurrence
Ortilles, JAVMA, 2020
What are the major and minor salivary glands
Major:
- Parotid
- Mandibular
- Sublingual
- Zygomatic
Minor:
- Buccal
- Lingual
- Labial
- Tonsillar
- Palatine
- Molar (well deveopled in cats, sit just deep to buccal mucosa at angle of mandible)
(BLLT with Potato Mash)
- Molar
By what structures is parotid salivary gland bounded?
Caudally:
- Sternomastoid m
- Cleidocervicalis m
Cranial:
- Masseter m
Ventral:
- Mandibular salivary gland
Superficial:
- Platysma
- Parotidoauricularis
Deep:
- Auricular cartilage of ear
(Surrounding structures: facial nerve, maxillary and temporal arteries, internal maxillary vein, and regions surrounding the external acoustic meatus and the stylomastoid foramen)
Label the diagram
Where does parotid duct open?
Oral vestibule lateral upper 4th premolar (carnassial)
Travels over ventral 1/3rd of masseter
Which LNs does parotid salivary gland drain into?
- Medial retropharyngeal
- Parotid
N.B. All major salivary glands drain into medial retropharyngeal and parotid gland also drains into parotid glands
What is the arterial supply to parotid salivary gland?
And venous drainage
Arterial: Parotid artery (branch of external carotid - runs along medial aspect vetral to external ear canal)
Venous: Superficial temporal and great auricular veins
Which nerve supplies parasympathetic innervation to the following salivary glands:
Parotid
Zygomatic
Mandibular
Sublingual
- Parotid: Trigeminal (auriculotemporal n.)
- Zygomatic: Glossopharyngeal
- Mandibular: Trigeminal (lingual n) + facial
- Sublingual: Trigeminal (lingual n) + facial
How many ducta are there from the zygomatic salivary gland
One major, up to 4 minor
Where does zygomatic salivary gland sit reltive to LN in orbital space
Salivary gland is lateral
Where do zygomatic salivary ducts open
Oral vestibule, caudal to upper last molar (usually 1cm caudal to parotid papilla)
What is the arterial supply and venous drainage of zygomatic salivary gland
Draining LN?
Arterial: Infraorbital artery
Venous: Deep facial vein (–> superficial temporal –> maxillary)
Ln: medial retropharyngeal
What anatomical structure can be used to locate mandibular salivary gland?
Junction between maxillary and linguofacial vein
Where does mandibular LN sit relative to mandibular salivary gland?
Ventromedially
Where does mandibular salivary duct open?
And sublingual?
Both open at sublingual caruncle, sublingual duct opens just caudal tomandibular duct.
(Ducts travels between styloglossus and mylohyoideus)
What is arterial supply to mandibular salivary gland.
And venous drainage
And to sublingual gland:
Mandibular:
- Arterial: Glandular branch of facial artery
- Venous: Lingual vein
Sublingual:
- Aretrial: Glandular branch of facial artery to monostomatic part, sublingual branch of lingual artery to polystomatic part
- Venous: Satellite veins alongside arteries
Whatare the portions of the sublingual salivary gland
Monostomatic:
- Found within the capsule shared by the mandibular salivary gland
- External to the capsule the gland continues rostrally in close association with the mandibular duct but is packaged in loose clusters of glandular tissue deep to the digastricus and mylohyoideus muscles. Sublingual salivary tissue caudal to the lingual nerve empties into the sublingual duct and is considered a monostomatic salivary gland
Polystomatic
- The polystomatic salivary tissue consists of small clusters of glandular tissue rostral to the lingual nerve that typically empty directly into the oral cavity.
Which salivary glands produce more serous secretion (vs more mucous)
Parotid + mandibular = more serous
riefly explain pathophys of salivary gland secretion (i..e composition of what is excreted)
- Phase one: Production of saliva within the acinus. The acinar cells absorb Na+, which helps to draw water in, creating sodium-rich saliva. Saliva flows into the collecting ducts.
- Phase two: Active reabsorption of Na+ and secretion of HCO3−.This process occurs mainly in the intralobular duct epithelium, which is formed by tall columnar epithelial cells. The resultant saliva excreted into the oral cavity is rich in HCO3− and K+
List 5 functions of saliva
- Lubrication
- Themroregulation
- Cleansing
- Buffering of weak acids
- Reduction of oral bacterial growth
List 2 non surgical ddx for salivary gland disease. How is one distinguished form the other
-
Sialadenosis (limbic epilepsy) –> bilat non-painful, non-inflammatory SG swelling.
- Tx pheno
-
Non-infecetious sialadenitis and necrotising sialometaplasia –> painful. Dx with histo (not cyto as easy to confuse).
- Histo = lobular necrosis, inflammation, squamous metaplasia, infarction, hypertrophy of ductal epithelium.
- Often associated with underlying GI disease
- Tx adrress any underlying GI issues and pheno
Name the four sialocoele locations - which gland is usually responsible. Most common presenting sign?
- Zygomatic - zygomatic gland - exophtalmos
- Pharyngeal - mandibular/sublingual complex - laboured breathing
- Cervical - sublingual - intermandibular/cervical swelling
- Sublingual (ranula) - rostral sublingual - dysphagia
Where is most common source of sialocoele?
Sublingual gland/duct –> cervical sialocoele
List 4 breeds predisposed to sialocoeles
GSD
Austrlian Silky terrier
Poodle
Dachshund
What is usual cytology from a sialocoele
What additional test can be run
- Non-degenerate neutrophils
- Macrophages with abundant, foamy cytoplasm
- Proteinaceous background
- (Plasma cells, few lymphocytes)
PAS (periodic acid Schiff staining for mucin)
On top of the usual - what additinal test can be used to investiagte sialocoeles
Sialography
What breed is pedisposed to pharyngeal sialocoeles
Concurrent findings?
Mini poodles
Males
43% also had cervical sialocoeles
How shoudl pharyngeal sialocoeles be managed?
Marsupialization + removal of offending gland/duct (usually mandibular/sublingual complex)
Often need immediate interventions due to airway compromise. Be prepeared for tach
List a non neoplastic ddx for cervical sialocoele
Branchial cleft cyst
How is sublingual sialocoele managed
Marsupialization + removal of mandibular/sublingual saloivary gland complex
List 5 post-op complications after cervical sialadenectoym
- Seroma
- Recurrence (<5%)
- Infection
- Sublingual swelling
- Bleeding
Where are sialoliths most commonly found
ddx?
Parotid duct
ddx: mineralised folds of sialocoele lining that have sloughed
Comment on image
Transverse T2-weighted magnetic resonance image with fat saturation of the head at the level of the zygomatic arch (yellow outline). This image demonstrates a normal zygomatic salivary gland (yellow star) as well as a zygomatic sialocele (black star).
List 4 methods for sialolith tx
- R+A
- Removal of gland/duct complex
- Open + primary repair
- Marsupialization
What is most common salivary gland neoplasia?
Which galnds most commonly affected
Adenocarcinoma
Mandibular and parotid
What % of dogs has LN mets with salivary gland neoplasia?
And cats?
17% dogs
39% cats
In dogs with salivary gland neplasia, what factor affects prognosis
Disease stage (not grade)
Name 2 approaches for mandibular/sublingual sialadenectomy
Describe ventral apporach to mandibular/sublingual sialadenectomy
Can do ventral or lateral apprach
Ventral
- Incision from a point 4 to 5 cm caudal to the mandibular ramus on the affected side and extending rostrally toward the mandibular symphysis (midline if bilateral sialadenectomy)
- Platysma muscle incised to facilitate identification of the external jugular bifurcation (to maxillary v and linguofacial v); the mandibular gland sits at or just cranial to this bifurcation.
- Tissues are bluntly dissected to expose the capsule covering the mandibular and sublingual salivary glands (N.B. ensure not LNs)
- The capsule over both glands is incised and bluntly dissected off the glandular tissue to facilitate ligation of vessels on the medial side of the gland.
- The gland complex is then retracted caudally to allow blunt dissection of the sublingual gland under (dorsal to) the digastricus muscle.
- With a hemostat placed from rostral to caudal under the digastricus muscle, the ducts are clamped just rostral to the large glandular complex, and the mandibular and main sublingual gland are excised.
- The remaining ducts and sublingual glands are pulled under the digastricus muscle.
- Blunt and sharp dissection are continued rostrally to the level of the lingual nerve. The the mylohyoideus muscle is incised for best exposure of the rostral glandular tissue and lingual nerve (see Figure 88.14). Most intermandibular, cervical, or pharyngeal sialoceles resolve if duct and glandular tissue is removed up to the lingual nerve.
- If a ranula is present, however, dissection should continue rostral to the lingual nerve under the mylohyoideus to remove all of the glandular tissue up to the sublingual caruncle. The duct is ligated as rostrally as possible and transected.
Briefly decribe procedure for zygomatic sialadenectomy
- incision is made horizontally tover the dorsal aspect of zygomatic arch.
- The aponeurosis of the masseter muscle is reflected off of the ventral aspect of the zygomatic arch, and the orbital fascia is reflected dorsally.
- A portion of the rostrolateral zygomatic arch is removed, as necessary, with a bone saw or rongeurs to gain access to the region of the zygomatic gland.
- Orbital fat is dissected and retracted to gain access to glandular tissue. The gland resides medial to the zygomatic arch and adjacent to the globe on the rostroventrolateral aspect. However, careful dissection is required due to sensitive structures in that area and anatomic changes caused by the presence of the sialocele. The gland is gently retracted and dissected free from surrounding tissue. A branch of the infraorbital (malar) artery supplying the salivary gland is accessed for ligation by dorsal retraction of the gland.
What 2 muscles are inscised to get access to parotid salivary gland?
What vein has to be liagted and divided?
Platysma
Parotidoauricularis
Caudal auricular vein
How do things change if a parotid salivary gand problem includes a lateral cheek swelling
If clinical presentation included lateral cheek swelling, the accessory parotid gland just dorsal to the parotid duct should also be dissected free and removed.
During wound closure, superficial muscles and subcutaneous tissues are reapposed to minimize dead space.
look at this lovely diagram
look at this lovely diagram
