Transcript Anatomy And Physiology Of Salivary Glands

Dr. Supreet Singh Nayyar, AFMC
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Anatomy of Parotid, Submandibular, Sublingual
glands
Physiology – structure of glands, secretion of
primary fluid, neuronal control,
neurotransmitters
Factors affecting salivary flow & composition
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3 Pairs – Major
salivary glands
 Parotid
 Submandibular
 Sublingual
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Collection of salivary
tissue within oral
mucosa – Minor
salivary glands
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Ectoderm of oral cavity
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Solid bulb from oropharyngeal epithelium
 6 weeks - parotid gland
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Dichotomous branching of solid bulb,
development of lumen, condensation of
mesenchyme
Formation of primitive ducts
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Engulfment of facial nerve – 16th- 21st wk
Functional maturation after feeding is
established
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Lobulated, “inverted
pyramid”, extent
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Superficial, deep lobes
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Parotid space
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Borders - ant, post
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Surfaces – superficial,
superior, anteromedial,
posteromedial
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Condensed deep cervical fascia, tough,
inelastic surface component, thin deep layer
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Stylomandibular ligament
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Fibrous septa arise from capsule
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Contents of fascia – superficial lymph nodes,
greater auricular nerve
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• Facial nerve,
division of gland
• Retromandibular
vein, anterior and
posterior divisions
• External carotid
artery, terminal
branches
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Capsule – Periparotid Nodes
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Mostly superficial to Facial Nerve
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Part of MALT, secrete IgA
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Salivary gland tissue may be present within the
lymph nodes
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Stylomastoid foramen
Methods of identification
during surgery
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TM Sulcus
PBD
Tragal pointer
Mastoid
Retrograde
Styloid process
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Varied, Surgically
important
Single trunk, divides into
Zygomaticotemporal,
Cervicomandibular
Temporal, upper / lower
zygomatic, buccal
Buccal, cervical,
mandibular
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Type1-5 ( Katz and Catalano, 1987)
 Type 1 (25%) – No anastomotic links
 Type 2 (14%) – Buccal fuses distally with Zygomatic
 Type 3 (44%) – Major communication between Buccal &
others
 Type 4 (14%) – Anastomosis between major divisions
 Type 5 (3%) – More than one Facial Nv trunk
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Unpredictable preoperatively, to be precisely
defined during surgery
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Parasympathetic
Inferior salivatory nucleus
IX nerve
Lesser Petrosal nerve
Otic ganglion
Sympathetic
Superior cervical ganglion
Plexus around ECA
PAROTID
Auriculotemporal nerve
PAROTID
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Formed near the anterior
border
Lies on superficial
surface of Masseter
Opens in the mouth at
parotid papilla
Accessory Parotid tissue
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Development
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6th IU wk
Ectoderm in floor of primitive oral cavity
Lateral to primitive tongue
Development of acini – 12th wk
Large superficial, small deep lobe
Located in Submandibular triangle
Well defined capsule
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Superficial Lobe
 Inferior surface –
Digastric, Deep fascia,
Platysma, Skin
 Lateral surface –
Submandibular fossa,
Facial artery
 Medial surface – Mylohyoid,
Hyoglossus, Lingual nerve, XII
nv, Submandibular ganglion,
Deep lingual vein
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Extends for a variable distance between
Mylohyoid & Hyoglossus
Relations
 Superior – Lingual nerve
 Inferior – XII Nv, Deep lingual vein, Submandibular duct
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5 cm in length
Middle of deep part
Crosses Sublingual space
Proximally – b/w Mylohyoid & Hyoglossus
Distally – b/w Genioglossus & Sublingual gland
Opening – on sides of frenulum of tongue
Relation to Lingual nerve
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Branches of Facial & Lingual arteries
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Lymph nodes adjacent to the superficial part
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Parasympathetic
Superior Salivary Nucleus
Nervus Intermedius
Facial Nerve
Chorda Tympani
Lingual Nerve
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Sympathetic
Superior Cervical Ganglion
Plexus around Facial Artery
Submandibular Ganglion
SUBMANDIBULAR GLAND
Submandibular Ganglion
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Skin incision – 4 cm below Mandible
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Ligation of Facial vessels above & below
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Dissected away from Lingual Nerve
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Lymph nodes in substance of gland
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Development
 8th wk
 Epithelial buds present
in paralingual sulcus
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Almond shaped
Located in anterior
part of floor of
mouth
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Sup – Oral floor mucosa
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Inf – Mylohyoid
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Post – Deep part
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Med – Lingual nerve,
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Lat– Med surface of lower
Submandibular gland
Submandibular duct,
Genioglossus
Mandible
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Ducts
 Multiple
 Drain into oral cavity directly or into Submandibular
duct
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Blood supply
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Nerve supply
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Produce saliva – 1L / day (1ml/min/gm)
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Contents
Mucin (glycoprotein)
Salivary amylase
Secretory Immunoglobulins
Other enzymes – DNase, RNase, lysozyme,
lactoperoxidase, lingual lipase
 Kallikerin
 Inorganic compounds – Na+, K+, HCO3-, Ca2+
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Lubrication and protection
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Buffering and clearance
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Maintenance of tooth integrity
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Antibacterial activity
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Taste and digestion
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Parotid
 Largest, serous (Compound Tubuloacinar Gland)
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Submandibular and Sublingual
 Mixed (Compound Tubuloacinar Glands)
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Serous Acini
◦ Pyramid shaped, basal
nucleus, apical
secretory granules
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Mucus Acini
◦ Larger, columnar cells,
basal nucleus
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Mixed Acini
◦ Mucus acini capped by
serous cells forming
Serous Demilunes
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Acini
Intercalated Ducts
Striated Ducts
Interlobular Excretory Ducts
Stenson’s, Wharton’s duct
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High rates
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Rate of saliva production – 1ml/min/gm
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Blood flow 10 times that of equal mass of
skeletal muscle
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Active transport process under neuronal
control
Composition
 Hypotonic to plasma
 Tonicity more when rates of production are high( at
max rate - 70% to that of plasma)
 K+,HCO3- higher than in plasma
 pH – acidic during resting phase, basic during active
phase(↑ HCO3- secretion)
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Acini – Primary Fluid Secretion
 Isotonic to plasma, electrolyte composition fairly
constant, exocrine protein
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Excretory ducts – extract Na+, Cl- and add K+,
HCO3- to saliva
 No addition in volume
 More of Na+, Cl- removed than addition of K+, HCO3responsible for hypotonicity
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Osmotic process
 Transepithelial salt gradients
 Four ion transport systems - luminal and basolateral
membranes generate the gradient
 Three mechanisms proposed – operate concurrently
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Stimulation – rise in cytosolic
Ca2+
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Opening of K+, Cl- channels –
KCl outflow
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Cl- conc in lumen ↑, Na+,
H2O follow
Cl- entry sustained via
Na+K+2Cl- cotransporter
6 Cl- translocated to acinar
lumen per ATP hydrolysed by
Na+/K+ ATPase
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Cl-/HCO3-, Na+/H+ exchanger
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KCl outflow
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Cl- entry via Cl-/HCO3exchanger
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Acidification buffered by
Na+/H+ exchanger
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3 Cl- translocated to lumen per
ATP hydrolysed
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Na+ & water follow into the
lumen
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Involves acinar HCO3secretion
3 HCO3- secreted per ATP
molecule
H+ extruded via Na+/Hexchanger
Na+, H2O follow into the
lumen
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Contained in zymogen granules present in
serous acinar cells, ductal cells
Upon stimulation release contents in lumen by
exocytosis
Conc and rate varies with level and type of
stimulation
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Inconstant, underlying mechanisms partially
understood
Produce final hypotonic solution
Influence of tubular cells more when flow rate
is slow
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Predominant control – PARASYMPATHETIC
Sympathetic stimulation shorter and less
strong
Probable synergistic action
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 Primary fluid secretion
 Protein secretion
 Vasodilatation
 Increased metabolism and growth
 Myoepithelial cell contraction
LARGE VOLUME LOW PROTEIN OUTPUT
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 High protein secretion
 Vasoconstriction – decreased blood flow
 Myoepithelial cell contraction
LOW VOLUME HIGH PROTEIN OUTPUT
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Parasympathetic
◦ Ach binds to M3
Receptors
◦ Activation of G protein►
Phospholipase C ►IP3 &
DAG ► Intracellular
Ca2+
release, Protein
exocytosis
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Sympathetic
◦ Noradrenaline binds to
α1, β1 receptors
◦ Activation of G protein ►
Adenylate Cyclase
activation
►↑cAMP dependant Protein
Kinase ►protein exocytosis
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Unstimulated – Submandibular
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Stimulated – Parotid 2/3rd
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Acidic tastes – Max stimulation
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Sweet tastes – Least stimulation
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Psychic factors
Circadian rhythm
Diurnal variation
Age
Drugs
 Tricyclic antidepressants
 Phenothiazines
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Depression and anxiety states
Dehydration, hemorrhage,
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Salivary Gland diseases
 Radiation sialadenitis
 Autoimmune sialadenitis
 HIV infection
 Iron overload
 Sarcoidosis
 Amyloidosis
 Cystic fibrosis
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Flow rate
Source of secretion
Type of stimulus
Diurnal variation
Diet
Drugs – flow dependant components
Hormones – mineralocorticoids, ovulation
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Disease states
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Sialadenitis
Radiation damage
Sjorgen’s syndrome
Cystic fibrosis
HTN
DM
Alcoholic cirrhosis
Aldosteronism
Chronic pancreatitis
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Valid medium, painless, non-invasive
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Hormone monitoring
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Unconjugated steroids
Proportional to free unbound plasma levels
Useful in field studies
Estradiol, progesterone, testosterone
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Drugs
 Factors – lipid solubility, protein binding, molecular
size, flow rates
 Constant saliva / plasma ratio not established
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Microbial antigens, antibodies
 Hepatitis A, B, C
 HIV
 Immunisation status
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Tc
99m
pertechnitate
Scintigraphy – objective measure of its uptake,
concenteration, excretion
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Concentric shells of calcareous material
alternating with organic material
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Stasis of flow
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Distribution
 Submandibular gland – 92%
 Parotid – 6%
 Sublingual / minor salivary glands – 2%
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Scott-Brown’s Otolaryngology – 6th ed, Vol 1,
Vol 5
Otolaryngology Head & Neck Surgery –Charles
W Cummings, 4th ed, Vol 2
Skandalakis’ Surgical Anatomy
Last’s Anatomy – 9th ed
Physiology – Berne & Levy, 5th ed
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