Seminar on salivary gland

1. SALIVARY GLAND
SALIVARY
GLAND
Presenter
- S. Lipi prakash

2. CONTENTS
1. INTRODUCTION
2. DEVELOPMENT OF SALIVARY GLAND
3. STRUCTURES OF SALIVARY GLAND
4. MAJOR SALIVARY GLANDS
5. MINOR SALIVARY GLANDS
6. PAROTID GLAND
7. SUBMANDIBULAR GLAND
8. SUBLINGUAL GLAND
9. SALIVA
10. CLINICAL CONSIDERATION

3. INTRODUCTION
Salivary glands are compound tubuloacinar exocrine glands that are found
in and around the oral cavity that secrete a complex fluid known as saliva into
the mouth
Saliva is a complex fluid secreted from three major salivary glands (i.e.,
parotid, submandibular, and sublingual), as well as from the numerous minor
salivary glands.
The ducts of the salivary glands carry the saliva and discharge it into the oral
cavity.
The saliva forms a film of fluid which prevents the attachment of bacteria to
the dentition and oral mucosa thereby creating and regulating a healthy
environment in the oral cavity

4. DEVELOPMENT OF SALIVARY GLAND
All salivary glands arises from ectoderm of oral cavity.
The minor salivary glands arises from the oral ectoderm and nasopharyngeal ectoderm.
The primordia of Parotid and submandibular – 6th week of intrauterine life
Sublingual – 7th week of intrauterine life
Minor salivary glands – 3rd month of intrauterine life
Mesoderm forms the intervening connective tissue septa
Signaling molecules include FGF, TGF -beta
Ref Inderbir Singh’s human embryology eleventh edition

5. Salivary gland develops near the junctional area between the
ectoderm of the stomatodeum and the endoderm of the foregut.
During fetal life, each salivary gland is formed at a specific location
in the oral cavity through the growth of a bud of oral epithelium into
the underlying mesenchyme
The epithelial bud grows into an extensively branched system of
cords of cells that are first solid but gradually develop a lumen and
become ducts.
The secretory portions develop later than the duct system
Ref Inderbir Singh’s human embryology eleventh edition

6. Ref Inderbir Singh’s human embryology eleventh edition

7. STRUCTURES OF SALIVARY GLAND
The secretory units are known as acini and the secretions are carried by tubules,
which open into the oral cavity- tubuloacinar in nature
The terminal secretory units or acini are made up of secretory cells , which are
either serous or mucous
The secretions of the terminal end pieces pass through the intercalated duct
Secretions from the intercalated duct passes through the striated duct
Saliva passes from striated duct to terminal excretory duct
Myoepithelial cells are the contractile cells with numerous processes associated
with salivary gland. These are non secretory cells found in close association with
terminal secretory end-piece and intercalated duct.
Ref Orban’s oral histology and embryology

8. SEROUS CELL
SEROUS ACINI
•Pyramidal in shape with narrow apex near the
lumen
•Sperical nucleus near basal one third
•Apical portion contains zymogen granules
•Secretion of granules as string of pearls no -
loss of cytoplasm
•Spherical in shape
•Smaller in size
•Have smaller lumen
•Intercellular canaliculi is present
•Secretion – enzymatic activity- acid
phosphatase, esterases, glucuronidase
•Produce secretory proteins , carbohydrate
content less. Produces thin watery fluid
•Serous acini help digest starch
Ref Orban’s oral histology and embryology

9. Ref Orban’s oral histology and embryology

10. •Pyramidal in shape
•Flattened nucleus at base
•Apical portion of cell appears empty
•Apical cytoplasm not sealed – mucus spilled into
lumen
MUCOUS
CELL
MUCOUS
ACINI
•Elliptical in shape
•Larger in size
•Have larger lumen
•Lacks intercellular canaliculi
•Secretion – no enzymatic activity
•Produces more carbohydrate components than proteins,
thick viscous fluid that contains mucin, a glycoprotein
•Mucous mainly serves as lubricant and protective layer
Ref Orban’s oral histology and embryology

12. Ref Orban’s oral histology and embryology

13. Ref Orban’s oral histology and embryology

14. INTERCALATED
DUCTS
Location- Intralobular
Cell morphology – single layer of low cuboidal
cells
Size- smallest in diameter
Function – contribute to macromolecular
components like lysozymes and lactoferrin

15. STRIATED
DUCTS
 Location- intraglobular
 Cell morphology- single layer of tall columnar
cells
 Size- bigger than intercalated duct
 Functions- site for electrolyte reabsorption-
active transport
 These cells shows striations and they are due
to deep infoldings of plasma membrane and
contains such mitochondria
Ref Orban’s oral histology and embryology

16. EXCRETORY
DUCTS
Location- Interlobular
Cell morphology – pseudostratified
columnar epithelium to stratified squamous
Size – largest in diameter
Function – no modification to saliva

17. Ref Orban’s oral histology and embryology

18. MAJOR SALIVARY GLANDS
There are three bilaterally paired major salivary glands , which are located
extraorally , and their secretions reach the mouth by variably long ducts.
 Parotid gland (purely serous)
Submandibular gland ( mixed gland predominantly serous)
Sublingual gland ( mainly mucous)

20. MINOR SALIVARY GLAND
Labial and buccal glands
Glossopalatine glands
Palatine glands
Anterior Lingual glands(Blandin-Nuhn
glands)
Posterior lingual glands (Von Ebner
glands)

21. PAROTID GLAND
Largest major salivary gland
Superficial portion – lies in front of the external ear
Deeper portion – lies behind the ramus of the mandible filling the
retromandibular fossae
It weighs between 14 and 28 g.
The main excretory duct- Stenson’s duct which opens at buccal mucosa
opposite to maxillary second molar .The duct measures 4–6 cm in length
and 5 mm in diameter.
Pure serous gland
Purely serous secretion and contributes to 25% of saliva
Flow rate – 0.4ml/min (unstimulated)
- 1-2 ml/min ( stimulated )
Ref B D Chaurasia’s Human Anatomy Volume 3 ‘Head and Neck’ 7 th edition

23. The parotid gland receives its blood supply from the branches of the external
carotid artery.
Venous drainage is through external jugular vein and internal jugular vein.
The parasympathetic nerve supply is derived mainly from the ninth cranial
nerve reaching the gland via the otic ganglion and the auriculotemporal nerve.
Sympathetic (vasomotor)- plexus around middle meningeal artery
Sensory – auriculotemporal nerve and greater auricular nerve
The lymphatic drainage is via paraparotid and intraparotid lymph nodes into the
superficial and deep cervical lymph nodes.
Ref B D Chaurasia’s Human Anatomy Volume 3 ‘Head and Neck’ 7 th edition

24. INFERIOR SALIVATORY NUCLEUS
9TH NERVE
TYMPANIC BRANCH
TYMPANIC PLEXUS
LESSER PETROSAL
RELAY IN OTIC GANGLION
POSTGANGLIONIC FIBRES THROUGH
AURICULOTEMPORAL NERVE
PAROTID GLAND

25. Ref B D Chaurasia’s Human Anatomy Volume 3 ‘Head and Neck’ 7 th edition

26. STRUCTURES
WITHIN THE
PAROTID GLAND
Most of the arteries and veins enter
through the posteromedial surface and
exit through the anteromedial surface
External carotid artery
Retromandibular vein
Facial nerve

27. Ref B D Chaurasia’s Human Anatomy Volume 3 ‘Head and Neck’ 7 th edition

28. HISTOLOGY OF PAROTID GLAND
Consists of lobular systems of ducts , seperated by connective tissue septa
Surrounded by dense connective tissue capsule
Pseudocapsule arises from investing layer of deep cervical fascia
Rich in serous cells
Tubules and ducts from acini contain myoepithelial cells

29. Clinical significance
Gustatory sweating (Frey’s syndrome/ auriculotemporal syndrome)
Occurs after parotid
surgery/trauma- results in opening of
parotid capsule
 Characterized by sweating,
warmth, redness of the face as a
result of salivary stimulation by smell
or taste of food
 Treatment- symptomatic- includes
SC infiltration of botox, anti-
perspirant or denervation (worst case)

30. Parotitis
 Inflammation
 Mostly caused by mumps
Cancers/tumors
80% are benign
Most common- Pleomorphic Adenoma, Warthin’s tumor
20%are malignant
Include MEC, ACC, adenocarcinoma

31. Parotid calculi (Sialolithiasis)
Either within the gland/ duct
Obstructs flow of saliva- swelling and pain
 Located by sialogram – These calculi can be located by injecting a
radiopaque dye through its opening in the vestibule of the mouth
Clinically , facial nerve palsy occurs after inferior alveolar nerve block.
An injection with long needle in the very posterior position of the
mandibular foramen could spread the anesthetic solution behind the mandibular
ramus but inside the parotid gland, as the parotid gland envelops the facial nerve,
thus leading to the direct anesthesia of the facial nerve
Ref. case report on facial nerve palsy after inferior alveolar nerve block : A rare presentation of
ocular complication and literature review by Glauco Chisci , Dafne Chisci, Enea Chisci

32. SUBMANDIBULAR GLAND
The submandibular gland is the second largest salivary gland.
It is placed posterior and superficial to the mylohyoid muscle.
The main excretory duct- Wharton’s duct, runs forward above the mylohyoid
muscle lying just below the mucosa of the floor of the mouth.
The gland receives blood supply from the lingual and facial arteries
The parasympathetic innervation is derived primarily from the VII cranial
nerve reaching the gland through the lingual nerve after synapsing in the
submandibular ganglion.
The lymphatic drainage is to the deep cervical and jugular chain of nodes.
Sensory fibers – lingual nerve
Postganglionic sympathetic fibers (vasomotor) –plexus surrounding the facial
artery

33. Contributes to 70% of saliva
Flow rate – 0.1 ml/min( unstimulated)
0.8ml/min ( stimulated)

34. Superior salivatory nucleus
Nervus intermedius
Facial nerve
Chorda tympani
Joins lingual nerve , branch of
mandibular nerve
Relay in submandibular ganglion
Postganglionic fibers
Submandibular gland
Ref B D
Chaurasia’s Human
Anatomy Volume 3
‘Head and Neck’ 7
th edition

35. CLINICAL SIGNIFICANCE
Submandibular duct calculi
80% of all salivary sialoliths
Tortuous duct course, different nature of
saliva predisposes to higher chances
They are formed by deposition of calcium
salts around a central nidus which consists of
altered salivary mucin , desquamated
epithelial cells, bacteria , foreign bodies
Modrate to severe pain – meals – psychic
stimulation of salivary flow associated with
swelling of the gland
Calculi in the Peripheral portion
may be palpated or sialography

36. Sialolithiasis
Ref Shafer’s textbook of oral pathology 8th edition

37. SUBLINGUAL GLAND
Smallest of the main salivary glands which is
almond shaped.
The sublingual gland is also a mixed
gland, but predominantly mucous
secretory units. Pure serous acini are rare
or absent
The main duct, Bartholin’s duct opens
with or near the submandibular duct and
duct of rivinus opens independently in
the floor of mouth
Contributes to 5% of saliva
Ref B D Chaurasia’s Human Anatomy Volume 3 ‘Head and Neck’ 7 th
edition

38. The sublingual gland receives its blood supply from the sublingual and the
submental arteries. The parasympathetic nerve supply is also derived from the
VII cranial nerve.It reaches the gland via the lingual nerve after synapsing in the
submandibular ganglion
The lymphatic drainage is to the submandibular lymph nodes

39. CLINICAL SIGNIFICANCE
Ranula
Retention cyst
When trauma occurs in the floor of the mouth and obstructs the drainage of
the gland, ranula is formed
 Large, tense, bluish swelling, often displacing the tongue

40. Mucocele [Mucous extravasation cyst]
It is mainly characterised by pooling of mucous in a cavity within the
connective tissue, due to the rupture of salivary duct or acini
Aetiology – Traumatic severance of a
salivary duct , by lip or cheek biting or
pinching of lips by extraction forceps
Involves accessory salivary gland
structures, Occurs most frequently in the
lower lip, also occur on palate cheek
tongue floor of mouth Treatment – Excision
Ref Shafer’s textbook of oral pathology 8th edition

41. The saliva is mainly produced by major salivary gland differ from one
another in composition.
The parotid gland secretes a watery saliva rich in enzymes such as amylase,
proline-rich protein, and glycoproteins.
The submandibular gland contains higher proportion of glycosylated
substances, such as mucin.
The sublingual gland produces a viscous saliva rich in mucin
The secretions of all the minor and major salivary glands contribute to
whole saliva.
SALIVA

42. CONSTITUENTS OF SALIVA

43. FUNCTIONS OF SALIVA
1. Protection and lubrication- Mucin, proline-rich proteins, water.
2. Antimicrobial action Lysozyme, lactoferrin, lactoperoxidases, mucins, cystatin,
histatins, IgM, PRP, IgA.
3. Mucosal integrity-Mucins, electrolytes, water
4. Dilution and cleansing -Water
5. Buffer capacity and remineralization-Bicarbonate, phosphate, calcium,
statherin, proline-rich anionic proteins, fluoride
6. Deglutition -Water, mucins
7. Digestion-Amylase, lipase
8. Taste
9. Phonation
10. Excretion (Through) water

44. AGE CHANGES IN SALIVARY GLANDS
Age changes in the salivary glands, particularly in the parotid, consist of a
gradual replacement of parenchyma with fatty tissue.
Since the parotid is the major source of serous saliva; with advancing age,
patients often complain of dryness and an increase in the viscosity of saliva

45. CLINICAL CONSIDERATION
Loss of salivary function or reduction in volume of saliva secreted is called
xerostomia, which leads to dryness of the mouth.
Oral tissues become susceptible to frequent oral infection; inflammation and
ulceration of oral mucosa is commonly seen. In some instances, excessive salivary
secretion is seen because of certain physiologic states and rare pathologies. This is
called sialorrhea
Increased salivary secretion (sialorrhea) can make isolation difficult during
restorative procedures
Decreased salivary production (xerostomia) can increase the risk of caries, tooth
loss and infections in the mouth

46. Owing to the opening of the Stenson’s duct opposite the maxillary 2nd molar,
there is a continuous discharge of saliva in this region, making isolation critical
The maxillary incisors are most vulnerable to caries, while the mandibular
incisors are the least vulnerable as they are protected by the saliva from the
submandibular and the sublingual glands
Ref Shafer’s textbook of oral pathology 8th edition

47. Xerostomia means dry mouth.
It is due to hyposalivation or absence of salivary secretion (aptyalism).
Causes
i. Dehydration or renal failure.
ii. Sjogren syndrome.
iii. Radiotherapy.
iv. Trauma to salivary gland or their ducts.
v. Side effect of some drugs like antihistamines, antidepressants,
monoamine oxidase inhibitors, antiparkinsonian drugs and antimuscarinic
drugs.
vi. Shock.
vii. After smoking
XEROSTOMIA

48.  Xerostomia causes difficulties in mastication, swallowing and speech.
 It also causes halitosis (bad breath; exhalation of unpleasant odors).
 Signs of xerostomia, including the following:
• Intraoral dryness
• Burning sensation
• Altered tongue surface
• Dysphagia
• Alterations in taste
• Difficulty with speech
• Root caries
 Xerostomia -Treated by saliva substitutes. Extensive dental caries is
common so frequent fluoride applications are indicated.

49. SJOGREN’S SYNDROME
Chronic, inflammatory, autoimmune disease affecting salivary, lacrimal and other
exocrine glands
 2 types- primary (dry eyes + dry mouth) and secondary (primary + RA/SLE)
Could be due to auto-antibodies (B cell hyperactivity), increased IgG or IgM, CMV,
lymph node malignancy
Features- Keratoconjunctivitis sicca, xerostomia, stomatitis, enlargement of salivary
glands, frothy saliva, mucosa is glazed, dry and wrinkled, severe dental caries,
periodontal disease, bacterial sialadenitis,enlarged and tender lymph nodes
Radiological features- Snowstorm/cherry blossom/branchless fruit laden tree
appearance
Treatment/management- Ocular lubricants, fluoride application, bromhexine,
pilocarpine surgery (only when enlargement is causing discomfort)

50. BRANCHLESS FRUIT
LADEN TREE
SNOWSTORM
Ref Shafer’s textbook of oral
pathology 8th edition

51. 1. Standring Susan. 2016. Gray's Anatomy : The Anatomical Basis of Clinical
Practice Forty-first ed. Philadelphia: Elsevier Limited
2. B D Chaurasia’s Human Anatomy Volume 3 ‘Head and Neck’ 7 th edition
3. Orban’s oral histology and embryology
4. Inderbir Singh’s human embryology eleventh edition
5. Shafer’s textbook of oral pathology 8th edition
REFERENCE