Anatomy salivary gland

1. SALIVARY GLANDS
DR. C.P. ARYA
M.D.S. IInd

2. Contents
1. Introduction
2. Development of salivary glands
3. Anatomy of salivary glands
• Parotid gland
• Submandibular gland
• Sublingual gland
• Minor Salivary glands
4. Histology of salivary glands
5. Disorders of salivary glands
6. Bibilography

3. Introduction
• Salivary glands are compounds
tubulo-acinar Exocrine glands
whose ducts open into the oral
cavity .
• Three major paired salivary
glands produce the majority of
saliva:
Parotid gland
Submandibular gland
Sublingual gland

4. OIn addition, 600-1,000 minor
salivary glands line the oral
cavity and oropharynx,
contributing a small portion of
total salivary production.

5. Development of salivary glands
OIndividual salivary glands arise as
a proliferation of oral epithelial
cells, forming a focal thickening
that grows into the under line
ectomesenchyme
OThe major salivary glands develop
from the 6th-8th weeks of
gestation as out-pouchings of oral
ectoderm into the surrounding
mesenchyme.

6. OThe parotid enlarge develops first,
growing in a posterior direction
as the facial nerve advances
anteriorly; eventually, the fully
developed parotid surrounds CN
VII. However, the Parotid gland is
the last to become encapsulated,
after the lymphatics develop,
resulting in its unique anatomy
with entrapment of lymphatics in
the parenchyma of the gland.

7. OFurther more , salivary epithelial
cells are often included within
these lymph nodes. This is felt to
play a role in the development of
Warthin’s tumors and Lympho-
epithelial cysts within the Parotid
gland.
OThe other major salivary glands do
NOT have intra-parenchymal
lymph nodes.

8. O The minor salivary glands arise from
oral ectoderm and nasopharyngeal
endoderm. They develop after the
major salivary glands.
O During development of the glands,
autonomic nervous system
involvement is crucial; sympathetic
nerve stimulation leads to acinar
differentiation while parasympathetic
stimulation is needed for overall
glandular growth.

9. Salivary
Glands

10. The Parotid Gland
O The parotid gland represents the
largest salivary gland, averaging 5.8
cm in the cranio-caudal dimension,
and 3.4 cm in the ventral-dorsal
dimension. The average weight of a
Parotid gland is 14.28 g.
O Lying wedged between the mandible
and sternocleidomastoid and
overflowing both these bounding
structures

12. O80% of the gland overlies the
Masseter and mandible.
O The remaining 20% of the gland (the
retro mandibular portion) extends
medially through the stylomandibular
tunnel formed by the posterior edge
of the mandibular ramus (ventral),
SCM and posterior belly of the
Digastric (dorsal), and the
stylomandibular ligament (deep and
dorsal).

13. O Arterial supply is provided by the
Transverse Facial artery from the
Superficial Temporal artery,
providing blood to the Parotid gland,
Stensen’s duct, and the Masseter
muscle. This artery runs between the
zygomatic arch and Stensen’s duct.
O Venous drainage is provided by the
Retro mandibular vein, which lies
deep to the Facial nerve. This vein
runs lateral to the Carotid artery, and
emerges at the inferior pole of the
Parotid gland.

14. OLymphatic drainage is unique in
the Parotid with Para parotid and
Intraparotid nodes.
OThe Para parotid nodes are more
numerous and drain the temporal
region, scalp, and auricle.
OThe Intraparotid nodes drain the
posterior nasopharynx, soft
palate, and ear.
OThe Parotid lymphatics drain into
the superficial and deep cervical
lymph nodes.

15. The Submandibular Gland
OThe submandibular gland is made
up of a large superficial and a small
deep lobe which connect with each
other around the posterior border
of the mylohyoid.
OThe superficial lobe of the gland
lies at the angle of the jaw, wedged
between the mandible and the
mylohyoid and overlapping the
digastric muscle .

18. OPosteriorly it comes into contact
with the parotid gland.
OSeparated only by a
condensation of its fascial sheath
(the stylomandibular ligament).

19. OSuperficially, the gland is
covered by platysma and by its
capsule of deep fascia, but it is
crossed by the cervical branch of
the facial nerve (VII) and by the
facial vein.
OIts deep aspect lies against the
mylohoid for the most part .

20. OThe lingual nerve reaches the
tongue by passing from the lateral
side of the duct below and then
medial to it—thus ‘double-
crossing’ it.
OThe submandibular lymph nodes
lie partly embedded within the
gland and partly between it and
the mandible.

21. OArterial supply to the
Submandibular gland comes from
the Submental branch of the Facial
artery (off of the External Carotid
artery).
O Venous drainage is provided by
the Anterior Facial vein, which lies
deep to the Marginal Mandibular
branch of CN VII.
OLymphatic drainage goes to the
deep cervical and jugular chains of

22. The Sublingual Gland
OThis is an almond-shaped salivary
gland (smallest) lying immediately
below the mucosa of the floor of
the mouth and immediately in front
of the deep part of the
submandibular gland.
OLaterally, it rests against the
sublingual groove of the mandible
.

23. OMedially it is separated from
the base of the tongue by
the submandibular duct and
its close companion, the
lingual nerve.
OThe sublingual gland lies
immediately lateral to the
submandibular duct.

24. OThe gland opens by a series of
ducts into the floor of the mouth
and also in the submandibular
duct.
OThe sublingual gland produces a
mucous secretion, the parotid a
serous secretion and the
submandibular gland a mixture of
the two.

25. OArterial supply to this gland is two-
fold:
1) The Sublingual branch of the
Lingual artery.
2) The Submental branch of the
Facial artery
OVenous drainage reflects the
arterial supply.
OLymphatic drainage goes to the
Submandibular nodes.

26. Minor Salivary Glands
OThe mucosa of the oral cavity
contains approximately 450 minor
salivary glands.
OThey are distributed in the mucosa
of the lips, cheeks, palate ,floor of
the mouth and retro molar area.

27. OThese minor salivary glands also
appear in other areas of the
upper autodigestive tract
including the oropharynx, larynx
and trachea as well as the
sinuses.
OThey contribute to 10% of the
total salivary volume.

28. OUnlike the major salivary glands,
the minor salivary glands lack a
branching network of draining
ducts.
OInstead, each salivary unit has its
own simple duct.
OThe minor salivary glands are
concentrated in the Buccal,
Labial, Palatal, and Lingual
regions.

29. OIn addition, minor salivary glands
may be found at the superior pole
of the tonsils (Weber’s glands),
the tonsillar pillars, the base of
tongue (von Ebner’s glands),
paranasal sinuses, larynx,
trachea, and bronchi.
OThe most common tumor sites
derived from the minor salivary
glands are the palate, upper lip,
and cheek.

31. Opening of Salivary Glands

32. Duct of Salivary Glands

33. The Parotid Duct
(Stensen’s Duct)
OThe parotid duct (of Stensen)
measures 4-6 cm in length and 5
mm in diameter.
OIt arises from the anterior part of
the gland, runs over the
masseters' finger’s breadth
below the zygomatic arch to
pierce the buccinators

34. OOpen opposite the second upper
molar tooth.
OThe duct can easily be felt by a
finger rolled over the masseter if
this muscle is tensed by
clenching the teeth.

35. The Submandibular duct
(Wharton’s duct)
O It exits the medial surface of the gland
and runs between the Mylohyoid
(lateral) and Hyoglossus muscles and
on to the Genioglossus muscle.
O Wharton’s duct empties into the
intraoral cavity lateral to the lingual
frenulum on the anterior floor of mouth.
O The length of the duct averages 5 cm.

36. The Sublingual Duct
(Ducts of Rivinus)
O Also unlike the Parotid and Submandibular
glands, the Sublingual gland lacks a single
dominant duct.
O Instead, it is drained by approximately 10
small ducts (the Ducts of Rivinus), which
exit the superior aspect of the gland and
open along the Sublingual fold on the floor
of mouth.
O Occasionally, several of the more anterior
ducts may join to form a common duct
(Bartholin’s duct), which typically empties
into Wharton’s duct.

37. Histology of Salivary units

38. O The secretory unit (salivary unit) consists of
the acinus, myoepithelial cells, the intercalated
duct, the striated duct, and the excretory duct.
O Acini, responsible for producing the primary
secretion, are divided into 3 types:
1) Serous (protein-secreting)=spherical cells
rich in zymogen granule
2) Mucous (mucin-secreting)=more tubular
shaped cells; mucinogen granules are
washed out on H&E preparations giving an
empty cell appearance
3) Mixed=serous demilunes, or predominantly
mucous acinar cells capped by a few serous
acinar cells.

39. OMyoepithelial cells send numerous
processes around the acini and
proximal ductal system (intercalated
duct), moving secretions toward the
excretory duct.
OThe Intercalated duct is lined by low
cuboidal epithelial cells rich in
carbonic anhydrase. These cells
secrete bicarbonate into the ductal
lumen and absorb chloride from the
lumen.

40. O The striated duct is lined by simple
cuboidal epithelial cells proximally with in
foldings of the basal and basolateral
plasma membrane and associated
mitochondria(producing “striations”).
These cells absorb Na from the lumen,
secrete K into the lumen, and produce an
increasingly hypotonic fluid.
O Excretory ducts are lined by simple
cuboidal epithelium proximally and
stratified cuboidal or pseudo stratified
columnar epithelium distally. These cells
do NOT perform any modification of the
saliva.

41. SALIVA
O In general, saliva is composed of 99.5%
water in addition to proteins,
glycoproteins, and electrolytes.
O Saliva is high in potassium (7x plasma),
bicarbonate (3x plasma), calcium,
phosphorous, chloride, thiocyanate,
and urea.
O Saliva is low in sodium (1/10 x plasma).
The normal pH of saliva is 5.6-7.

42. Function of Saliva
O At least 8 major functions of saliva have been
identified (8):
1) Moistens oral mucosa. In fact, the mucin
layer on the oral mucosa is thought to be the
most important nonimmune defense mechanism
in the oral cavity.
2) Moistens dry food and cools hot food.
3) Provides a medium for dissolved foods to
stimulate the taste buds.
4) Buffers oral cavity contents. Saliva has a high
concentration of bicarbonate ions.

43. 5) Digestion. Alpha-amylase, contained in saliva,
breaks 1-4 glycoside bonds, while lingual lipase
helps break down fats.
6) Controls bacterial flora of the oral cavity.
7) Mineralization of new teeth and repair of
precarious enamel lesions. Saliva is high in
calcium and phosphate.
8) Protects the teeth by forming a “Protective
Pellicle”. This signifies a saliva protein coat on
the teeth which contains antibacterial
compounds. Thus, problems with the salivary
glands generally result in rampant dental caries.

44. Flow of saliva
O The average volume of saliva
secreted in a 24 hour period is 1-1.5
liters.
O (approximately 1 cc/minute), most
of which is secreted during meals.
O The basal salivary flow rate=0.001-
0.2 ml/minute/gland.

45. O With stimulation, salivary flow
rate=0.18-1.7 ml/min/gland.
O Salivary flow rate from the minor
salivary glands is independent of
stimulation.
O constituting 7-8% of total salivary
output.

46. OIn the UNSTIMULATED state the
relative contribution of the major
salivary glands is as follows:
1) Submandibular gland=69%
2) Parotid gland=26%
3) Sublingual gland=5%

47. OIn the STIMULATED state the
relative contribution of the major
salivary glands is as follows:
1) Parotid gland=69%
2) Submandibular gland=26%
3) Sublingual gland=5%

48. DISORDERS OF SALIVARY
GLAND
Developmental Obstructive Infectious Idiopathic
1.Heterotropic
salivary gland
1.Mucus escape
reaction
A. Mucocele
B. Ranula
1.Tuberculosi
s
1.Necrotizing
Sialometaplasia
2.Accessory
salivary glands
2.Mucus retention
cyst
2.Cat-scratch
disease
2.Lymphoepithelial
cyst
3.Onocytosis 3.Sialolithiasis 3.Mumps 3.Salivary duct
cyst
4.Adenomatoid
glandular
hyperplasia
4.Salivary
gland cyst as
manifestation
of AIDS
4.Angiolymphoid
hyperplasia with
Eosinophilia
5.Polycystic
disease
5.Sialadenosi
s
5.Kimura’s Disease

49. BIBILOGRAPHY
1. Fox PC. Acquired Salivary Dysfunction: Drugs and Radiation.
Ann New York Acad Sci. 1998; 842: 132-137.
2. Eisele DW, Johns ME. Salivary Gland Neoplasms. Head and
Neck Surgery- Otolaryngology, Second Edition, ed. Byron J.
Bailey. Lippincott-Raven Publishers, Philadelphia, PA 1998:
1485-1486.
3. Isenman L, Liebow C, Rothman S. The Endocrine Secretion of
Mammalian Digestive Enzymes. Am J Physiol. 1999; 276: E223-
E232.
4. Jensen JL, Bankroll P. Clinical Implications of Dry Mouth: Oral
Mucosal Diseases. Ann New York Acad Sci. 1998; 842: 156-162.

50. 5. Kontis TC, Johns Me. Anatomy and
Physiology of the Salivary Glands. Head
and Neck Surgery-Otolaryngology, Second
Edition, ed. Byron J. Bailey. Lippincott-
Raven Publishers, Philadelphia, PA. 1998:
531-539.
6. Mattes RD. Physiologic Responses to
Sensory Stimulation by Food: Nutritional
Implications. J Am Diet Assoc. 1997; 97:
406-410, 413.

51. 7. Moore KL. Clinically Oriented Anatomy. Third
Edition. Williams and Wilkins. Baltimore, MD. 1992:
670-671, 751-752.
8. Ross MH, Romrell LJ, Kaye GI. Histology: A Text
and Atlas. Third Edition. Williams and Wilkins.
Baltimore, MD. 1995: 417-439.
9. Silvers AR, Sum PM. Salivary Glands. Head and
Neck Imaging. 1998; 36: 941-966.

52. THANK
YOU