Anatomy and Physiology of the Salivary Glands and Sialography


Types of salivary glands

The Major Salivary Glands
  • Parotid
  • Submandibular
  • Sublingual
The Minor SalivaryGlands
 
Embryology
  • 6th-8th Weeks of Gestation
  • Parotid
    • First to develop
    • Last to become encapsulated
  • Autonomic Nervous System Crucial
Anatomy of Parotid Gland
  • Wedge shaped with 5 processes
    • 3 Superficial
    • 2 Deep
  • Parotid Compartment
    • Superior – Zygoma
    • Posterior – EAC
    • Inferior – Styloid, ICA, Jugular Veins
  • 80% overlies
  • Masseter & Mandible
  • 20% Retromandibular
  • Stylomandibular,Tunnel, Isthmus of Parotid
  • Tail of Parotid
Parapharyngeal Space
  • Prestyloid Compartment
  • Poststyloid Compartment (Paragangliomas)
Stensen’s Duct
  • Arises from anterior border
  • 1.5 cm inferior to Zygomatic arch
  • Pierces Buccinator at 2nd Molar
  • 4-6 cm in length
  • 5 mm in diameter
Parotid Capsule
  • Superficial layer Deep Cervical Fascia
  • Superficial layer
  • Deep layer
 


CN VII-Facial nerve
  • 2 Surgical zones
  • 3 Motor branches
  • immediately
  • Pes Anserinus – 1.3 cm
  • Temperofacial Division
  • Cervicofacial Division
  • 5 Terminal branches
Localization of CN VII
  • Tragal pointer
  • Tympanomastoid suture
  • Posterior belly Digastric
  • Styloid process
  • Retrograde dissection
  • Mastoidectomy
  • Great Auricular nerve
  • Auriculotemporal nerve
    • Superficial Temporal vessels
    • Frey’s Syndrome
Neural compartment-VII, Great Auricular, Auriculotemporal
Venous compartment-Retromandibular vein
Arterial compartment-Superficial Temporal/Transverse Facial

Lymphatics
  • Paraparotid & Intraparotid nodes
  • Superficial & Deep Cervical nodes
Submandibular Gland-Anatomy
 
  • The ‘Submaxilla’
  • Submandibular Triangle
  • Mylohyoid ‘C’
  • Marginal Mandibular branch
  • Capsule from superficial layer of Deep Cervical fascia
Wharton’s duct
  • Exits medial surface
  • Between Mylohyoid & Hyoglossus
  • 5 cm in length
  • Lingual nerve & CN XII
Innervation
Superior Cervical Ganglion (symp)
Submandibular Ganglion (para)
Artery: Submental branch of Facial a.
Vein: Anterior Facial V nerve.
Lymphatics: Deep Cervical and Jugular chains
Facial artery nodes
Between Mandible & Genioglossus
No capsule
Ducts of Rivinus +/- Bartholin’s duct
Sialogram not possible
Innervation: Same as Submandibular
Artery/Vein: Sublingual branch of Lingual & Submental branch of Facial
Lymphatics: Submandibular nodes

Minor Salivary Glands

  • 600-1,000
  • Simple ducts
  • Buccal, Labial,
  • Palatal, Lingual
  • Tumor sites:
  • Palate, upper lip,cheek
  • Lingual & Palatine nn.
Imaging of Salivary Gland-Important things to remember
  • CT – Inflammatory
  • MR – Tumor
  • Children: U/S & MR
  • NO sialogram during active infection
  • Parotid is fatty
The Secretory Unit
  • Acinus (serous, mucous, mixed)
  • Myoepithelial cells
  • Intercalated duct
  • Striated duct
  • Excretory duct
Microanatomy of Salivary glands
  • Striated & Intercalated ducts well developed in serous, NOT mucous glands
  • Striated duct: HCO3 into, Cl from lumen
  • Intercalated duct: K into lumen, Na from lumen, producing hypotonic fluid
  • Excretory ducts do NOT modify saliva
 
The Bicellular Theory
  • Intercalated duct
  • Excretory duct
The Multicellular Theory

Parotid: serous & fatty
Submandibular: mixed serous
Sublingual: mixed mucous
Stroma: Plasma cells

Function of Saliva
  1. Moistens oral mucosa
  2. Moistens & cools food
  3. Medium for dissolved food
  4. Buffer (HCO3)
  5. Digestion (Amylase, Lipase)
  6. Antibacterial (Lysozyme, IgA, Peroxidase, FLOW)
  7. Mineralization
  8. Protective Pellicle
 
Effects of Salivary hypofunction
  • Candidiasis
  • Lichen Planus
  • Burning Mouth
  • Aphthous ulcers
  • Dental caries
  • Xerostomia not reliable
 
Production of Saliva

  • Primary secretion
  • Ductal secretion
  • The “secretory potential”
  • (hyperpolarizes)
  • Increased flow rate yields decreased
  • hypotonicity & K
Autonomic Innervation
Parasympathetic
  • Abundant, watery saliva
  • Amylase down
Sympathetic
  • Scant, viscous saliva
  • Amylase up
Salivary Flow
  • 1-1.5 L/day (1 cc/min)
  • Unstimulated state
  • Submandibular
  • Stimulated state
  • Parotid
  • Sublingual & minor
  • Mucin
Effects of Aging
Total salivary flow independent of age
Acinar cells degenerate with age
Submandibular gland more sensitive to metabolic/physiologic change
Unstimulated salivary flow more greatly affected by physiologic changes

Sialography
Radiologic examination of the salivary glands
The submandibular and parotid glands are investigated by this method
The sublingual gland is usually not evaluated this way-Difficulty in cannulation

Indications
  • Ductal obstruction-Stones or tumors
  • Inflammation of a duct or gland
Contraindications
  • Severe infection of a gland
  • Known allergies to contrast media
Equipment
  • Fluoroscopic unit w/spot film capabilities
  • Cannula for introducing contrast
  • Connecting tubing
  • Lemons
  • Dilators for duct
  • 5 mL syringe
  • Overhead light
  • Gauze
  • Contrast
Preliminary and Procedure Radiographs
  • Parotid-Tangential
    • Perpendicular to cassette, directed to lateral surface of mandibular ramus
  • Submandibular-Lateral
    • Perpendicular to cassette, directed to 1 in. superior to mandibular angle to demonstrate parotid gland
    • Inferior margin of mandibular angle to demonstrate the submandibular gland
Patient Preparation
  1. Thorough explanation of examination
  2. Any removable dental work, jewelry, and other artifact causing opaque items must be removed
  3. Consent must be signed
Procedure
  • The patient first sucks on a lemon wedge to open the ducts
  • An overhead lamp is used to provide adequate light
  • The duct is cannulated, not punctured, and contrast is introduced with fluoroscopic guidance
  • Radiographs are obtained
  • After the radiographs, the patient then sucks on a lemon wedge to evacuate the contrast
  • Obtain post-procedure radiographs as indicated
Lateral Parotid Gland Radiograph


Lateral Submandibular Glands

 
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