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