Anatomy and physiology of salivary glands

Dr. Supreet Singh Nayyar, AFMC

For more topics, visit www.nayyarENT.com

 Anatomy of Parotid, Submandibular, Sublingual
glands

 Physiology – structure of glands, secretion of
primary fluid, neuronal
control, neurotransmitters

 Factors affecting salivary flow & composition

www.nayyarENT.com 7/13/2012 2

 3 Pairs – Major
salivary glands

 Parotid
 Submandibular
 Sublingual

 Collection of salivary
tissue within oral
mucosa – Minor
salivary glands


 Ectoderm of oral cavity

 Solid bulb from oropharyngeal epithelium
 6 weeks - parotid gland

 Dichotomous branching of solid bulb,
development of lumen, condensation of
mesenchyme

 Formation of primitive ducts


 Engulfment of facial nerve – 16th- 21st wk

 Functional maturation after feeding is
established


 Lobulated, “inverted
pyramid”, extent

 Superficial, deep lobes

 Parotid space

 Borders - ant, post

 Surfaces – superficial,
superior, anteromedial,
posteromedial


 Condensed deep cervical fascia, tough,
inelastic surface component, thin deep layer

 Stylomandibular ligament

 Fibrous septa arise from capsule

 Contents of fascia – superficial lymph nodes,
greater auricular nerve


• Facial nerve,
division of gland

• Retromandibular
vein, anterior and
posterior divisions

• External carotid
artery, terminal
branches


 Capsule – Periparotid Nodes

 Mostly superficial to Facial Nerve

 Part of MALT, secrete IgA

 Salivary gland tissue may be present within the
lymph nodes


 Stylomastoid foramen

 Methods of identification
during surgery

 TM Sulcus
 PBD
 Tragal pointer
 Mastoid
 Retrograde
 Styloid process


 Varied, Surgically
important

 Single trunk, divides into
Zygomaticotemporal,
Cervicomandibular

 Temporal, upper / lower
zygomatic, buccal

 Buccal, cervical,
mandibular


 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

 Unpredictable preoperatively, to be precisely
defined during surgery


Parasympathetic Sympathetic
Inferior salivatory nucleus Superior cervical ganglion

IX nerve
Plexus around ECA
Lesser Petrosal nerve
PAROTID
Otic ganglion

Auriculotemporal nerve

PAROTID


 Formed near the anterior
border

 Lies on superficial
surface of Masseter

 Opens in the mouth at
parotid papilla

 Accessory Parotid tissue


 Development
 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


 Superficial Lobe

 Inferior surface –
Digastric, Deep fascia,
Platysma, Skin

 Lateral surface –
Submandibular fossa,  Medial surface – Mylohyoid,
Facial artery Hyoglossus, Lingual nerve, XII
nv, Submandibular ganglion,
Deep lingual vein


 Extends for a variable distance between
Mylohyoid & Hyoglossus

 Relations
 Superior – Lingual nerve
 Inferior – XII Nv, Deep lingual vein, Submandibular duct


 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


 Branches of Facial & Lingual arteries

 Lymph nodes adjacent to the superficial part


 Parasympathetic  Sympathetic
Superior Salivary Nucleus Superior Cervical Ganglion

Nervus Intermedius
Plexus around Facial Artery
Facial Nerve

Chorda Tympani Submandibular Ganglion

Lingual Nerve
SUBMANDIBULAR GLAND
Submandibular Ganglion


 Skin incision – 4 cm below Mandible

 Ligation of Facial vessels above & below

 Dissected away from Lingual Nerve

 Lymph nodes in substance of gland


 Development
 8th wk
 Epithelial buds present
in paralingual sulcus

 Almond shaped

 Located in anterior
part of floor of
mouth


 Sup – Oral floor mucosa

 Inf – Mylohyoid

 Post – Deep part
Submandibular gland

 Med – Lingual
nerve, Submandibular
duct, Genioglossus

 Lat– Med surface of lower
Mandible


 Ducts
 Multiple
 Drain into oral cavity directly or into Submandibular
duct

 Blood supply

 Nerve supply


 Produce saliva – 1L / day (1ml/min/gm)

 Contents
 Mucin (glycoprotein)
 Salivary amylase
 Secretory Immunoglobulins
 Other enzymes –
DNase, RNase, lysozyme, lactoperoxidase, lingual lipase
 Kallikerin
 Inorganic compounds – Na+, K+, HCO3-, Ca2+


 Lubrication and protection

 Buffering and clearance

 Maintenance of tooth integrity

 Antibacterial activity

 Taste and digestion


 Parotid
 Largest, serous (Compound Tubuloacinar Gland)

 Submandibular and Sublingual
 Mixed (Compound Tubuloacinar Glands)


 Serous Acini
◦ Pyramid shaped, basal
nucleus, apical
secretory granules
 Mucus Acini
◦ Larger, columnar cells,
basal nucleus
 Mixed Acini
◦ Mucus acini capped by
serous cells forming
Serous Demilunes


Acini

Intercalated Ducts

Striated Ducts

Interlobular Excretory Ducts

Stenson’s, Wharton’s duct


 High rates

 Rate of saliva production – 1ml/min/gm

 Blood flow 10 times that of equal mass of
skeletal muscle


 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)


 Acini – Primary Fluid Secretion
 Isotonic to plasma, electrolyte composition fairly
constant, exocrine protein

 Excretory ducts – extract Na+, Cl- and add
K+, HCO3- to saliva
 No addition in volume
 More of Na+, Cl- removed than addition of K+, HCO3-
responsible for hypotonicity


 Osmotic process
 Transepithelial salt gradients

 Four ion transport systems - luminal and basolateral
membranes generate the gradient

 Three mechanisms proposed – operate concurrently


 Stimulation – rise in cytosolic
Ca2+

 Opening of K+, Cl- channels –
KCl outflow

 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


 Cl-/HCO3-, Na+/H+ exchanger

 KCl outflow

 Cl- entry via Cl-/HCO3-
exchanger

 Acidification buffered by
Na+/H+ exchanger

 3 Cl- translocated to lumen per
ATP hydrolysed

 Na+ & water follow into the
lumen


 Involves acinar HCO3-
secretion

 3 HCO3- secreted per ATP
molecule

 H+ extruded via Na+/H-
exchanger

 Na+, H2O follow into the
lumen


 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


 Inconstant, underlying mechanisms partially
understood

 Produce final hypotonic solution

 Influence of tubular cells more when flow rate
is slow


 Predominant control – PARASYMPATHETIC

 Sympathetic stimulation shorter and less
strong

 Probable synergistic action


 Primary fluid secretion

 Protein secretion

 Vasodilatation

 Increased metabolism and growth

 Myoepithelial cell contraction

LARGE VOLUME LOW PROTEIN OUTPUT


 High protein secretion

 Vasoconstriction – decreased blood flow

 Myoepithelial cell contraction

LOW VOLUME HIGH PROTEIN OUTPUT


 Parasympathetic

◦ Ach binds to M3
Receptors

◦ Activation of G protein
Phospholipase C IP3 &
DAG Intracellular
Ca2+
release, Protein
exocytosis


 Sympathetic

◦ Noradrenaline binds to
α1, β1 receptors

◦ Activation of G protein
Adenylate Cyclase
activation
↑cAMP dependant Protein
Kinase protein exocytosis


 Unstimulated – Submandibular

 Stimulated – Parotid 2/3rd

 Acidic tastes – Max stimulation

 Sweet tastes – Least stimulation


 Psychic factors
 Circadian rhythm
 Diurnal variation
 Age
 Drugs
 Tricyclic antidepressants
 Phenothiazines
 Depression and anxiety states
 Dehydration, hemorrhage,


 Salivary Gland diseases

 Radiation sialadenitis

 Autoimmune sialadenitis

 HIV infection

 Iron overload

 Sarcoidosis

 Amyloidosis

 Cystic fibrosis


 Flow rate
 Source of secretion
 Type of stimulus
 Diurnal variation
 Diet
 Drugs – flow dependant components
 Hormones – mineralocorticoids, ovulation


 Disease states

 Sialadenitis
 Radiation damage
 Sjorgen’s syndrome
 Cystic fibrosis
 HTN
 DM
 Alcoholic cirrhosis
 Aldosteronism
 Chronic pancreatitis


 Valid medium, painless, non-invasive

 Hormone monitoring
 Unconjugated steroids
 Proportional to free unbound plasma levels
 Useful in field studies
 Estradiol, progesterone, testosterone


 Drugs
 Factors – lipid solubility, protein binding, molecular
size, flow rates
 Constant saliva / plasma ratio not established

 Microbial antigens, antibodies
 Hepatitis A, B, C
 HIV
 Immunisation status


 Tc 99m pertechnitate

 Scintigraphy – objective measure of its
uptake, concenteration, excretion


 Concentric shells of calcareous material
alternating with organic material

 Stasis of flow

 Distribution
 Submandibular gland – 92%
 Parotid – 6%
 Sublingual / minor salivary glands – 2%


 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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