Salivary Glands and Oral Tissues

Question 1

What are the 3 types of oral mucosa?

Answer 1

Lining mucosa
Masticatory mucosa
Specialised mucosa

Question 2

What does the oral mucosa generally consist of?

Answer 2

Stratified squamous epithelium
Lamina propria of dense connective tissue
Submucosa of loose connective tissue

Question 3

What does masticatory mucosa cover and what is the epithelium like?

Answer 3

Covers hard palate and gingiva (gums around teeth)

Epithelium is keratinised or parakeratinised

Question 4

What does lining mucosa cover and what is the epithelium like?

Answer 4

Found on inside of lips, lining buccal surfaces, soft palate, floor of mouth and inferior surface of tongue
Epithelium is not keratinised

Question 5

What other oral areas are keratinised?

Answer 5

Dorsum of tongue

Vermillion border of lips

Question 6

What is the muscle in the tongue?

Answer 6

Extrinsic skeletal muscles inserting into tongue

Intrinsic skeletal muscle bundles in longitudinal, transverse and vertical planes

Question 7

What are the 4 types of tongue papillae and their structures?

Answer 7

Filiform - conical shape, no taste buds
Fungiform - blunt, taste buds
Foliate - slit like on margin of tongue, taste buds
Circumvallate - large dome shaped, taste buds

Question 8

Functions of saliva

Answer 8

Protection
Buffering
Tooth integrity
Antimicrobial activity
Digestion
Taste

Question 9

What are the 3 main pairs of salivary glands?

Answer 9

Parotid
Submandibular
Sublingual

Question 10

Where are minor glands typically located?

Answer 10

In the submucosa with short ducts opening directly onto mucosal surface

Question 11

Structure of parotid glands

Answer 11

Largest salivary glands
Pyramidal shape with apex below angle of mandible, posterior edge near external auditory meatus
External carotid artery, retromandibular vein and facial nerve all embedded in gland

Question 12

Where does the parotid duct emerge and where does it go?

Answer 12

Emerges from anterior border
Passes over masseter and pierces buccinator
Empties into oral cavity on a papilla opposite upper second molar tooth

Question 13

What is the parasympathetic innervation of the parotid gland?

Answer 13

Preganglionic: glossopharyngeal > lesser petrosal nerve > otic ganglion
Postganglionic: otic ganglion > auriculotemporal nerve > parotid gland

Question 14

Structure of submandibular gland

Answer 14

Superficial part visible below inferior border of mandible
Wraps around posterior border of mylohyoird muslce where there is a deeper portion
Facial artery grooves the superficial part

Question 15

Where does the submandibular duct emerge and where does it go?

Answer 15

Emerges from deep part of gland and passes forward to terminate on the sublingual caruncle near base of lingual frenum

Question 16

What is the parasympathetic innervation of the submandibular gland?

Answer 16

Preganglionic: facial nerve > chorda tympani > lingual nerve > submandibular ganglion
Postganglionic: submandibular ganglion > submandibular gland

Question 17

Structure of the sublingual gland

Answer 17

Almond shaped
Sits in sublingual fossa of inner aspect of mandible
Bounded above by oral mucosa, below by mylohyoid and medially by genioglossus

Question 18

Where does the sublingual duct emerge and where does it go?

Answer 18

Highly variable
Typically anterior part drains via a single duct that joins the submandibular duct
Posterior part drains via several small ducts that end on sublingual fold

Question 19

What is the parasympathetic innervation of the sublingual gland?

Answer 19

(same as submandibular)
Preganglionic: facial nerve > chorda tympani > lingual nerve > submandibular ganglion
Postganglionic: submandibular ganglion > sublingual gland

Question 20

Properties of the stroma of salivary glands

Answer 20

Covered by a tough connective tissue capsule with septa that pass inwar to divide the gland into lobes and then lobules
Blood vessels, nerves and major ducts travel in these septa

Question 21

Properties of the parenchyma of salivary glands

Answer 21

Compound tubulo-acinar glands
Secretory elements consist of serous acini, mucous acini and mixed acini
Merocrine secretion

Question 22

What is merocrine secretion?

Answer 22

Occurs by exocytosis
The membranes surrounding secretory vesicle fuse with cell membrane and discharge their contents to the extracellular space

Question 23

What are the two types of duct morphology?

Answer 23

Simple - duct is unbranched

Compound - has a branching duct system

Question 24

What is a tubuloacinar gland?

Answer 24

Secretory tubules or tubules ending in acini

Salivary glands are tubuloacinar glands

Question 25

What do serous cells secrete?

Answer 25

Thin watery secretion that contains proteins and ions

Question 26

What do mucous cells secrete?

Answer 26

Mucin - consists of a protein core that is highly decorated with sugar residues and results in a viscous, sticky secretion

Question 27

Structure of cells of the serous acini

Answer 27

Typically wedge shaped Prominent nucleus in basal part of cell Extensive rough endoplasmic reticulum Granular appearance due to large numbers of apical secretory vesicles

Question 28

Structure of cells of the mucous acini

Answer 28

Tend to be found in the tubular element of tubulo-acinar gland Large numbers of prominent secretory granules packing the cytoplasm Large granules compress the nucleus towards basal part of cell

Question 29

What is a serous demilune?

Answer 29

Cells of mixed acini appearing as a crescent shaped collection of cells at the end of the secretory unit

Question 30

Properties of myoepithelial cells

Answer 30

Speciailised epithelial cells for contraction | Form a network around groups of secretory cells and when they contract help to expel secretions from the gland

Question 31

Where do acinus empty?

Answer 31

Intercalated duct

Question 32

What makes an intercalated duct?

Answer 32

Cuboidal cells

Question 33

Where do intercalated ducts empty?

Answer 33

Striated duct

Question 34

What makes up a striated duct?

Answer 34

Columnar cells with a central nucleus and prominent striations

Question 35

What are the striations in a striated duct?

Answer 35

Infoldings of the cell membrane accompanied by lines of mitochondria to power the molecular pumps within the membranes

Question 36

What do molecular pumps do?

Answer 36

Pump Na+ ions out of saliva (Cl- ions follow) against concentration gradient hence need for lots of mitochondria and surface area Also pump K+ and HCO3- into saliva = hypotonic saliva

Question 37

Where do striated ducts empty?

Answer 37

Excretory ducts within connective tissue between lobules

Question 38

What lines excretory ducts?

Answer 38

Pseudostratified columnar epithelium with tall columnar cells and small basal cells As excretory ducts merge, they become larger and near opening of oral cavity the lining becomes stratified squamous epithelium (similar to oral mucosa)

Question 39

Amounts of each cell type in different glands

Answer 39

Parotid gland - all serous cells Submandibular gland - mostly serous, some mucous Sublingual gland - mostly mucous, some serous

Question 40

What different types of minor glands are there and where are they found?

Answer 40

Lingual glands - dorsal surface of tongue Minor sublingual glands - lower surface of tongue Labial glands - inner surface of lips Palatine glands - submucosa of soft and posterior hard palate Buccal glands - submucosa of cheek lining

Question 41

Where are von Ebner's glands?

Answer 41

Associated with circumvalate and foliate papillae and open into the base of the cleft surrounding the papillae

Question 42

Are minor glands serous or mucous?

Answer 42

Mostly mucous apart from von Ebners glands which are entirely serous

Question 43

Function of von Ebner's glands

Answer 43

Serous secretion helps dissolve food molecules to aid taste | Also keeps cleft flushed to allow for next taste