Salivary Glands and Oral Tissues Flashcards
What are the 3 types of oral mucosa?
Lining mucosa
Masticatory mucosa
Specialised mucosa
What does the oral mucosa generally consist of?
Stratified squamous epithelium
Lamina propria of dense connective tissue
Submucosa of loose connective tissue
What does masticatory mucosa cover and what is the epithelium like?
Covers hard palate and gingiva (gums around teeth)
Epithelium is keratinised or parakeratinised
What does lining mucosa cover and what is the epithelium like?
Found on inside of lips, lining buccal surfaces, soft palate, floor of mouth and inferior surface of tongue
Epithelium is not keratinised
What other oral areas are keratinised?
Dorsum of tongue
Vermillion border of lips
What is the muscle in the tongue?
Extrinsic skeletal muscles inserting into tongue
Intrinsic skeletal muscle bundles in longitudinal, transverse and vertical planes
What are the 4 types of tongue papillae and their structures?
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
Functions of saliva
Protection Buffering Tooth integrity Antimicrobial activity Digestion Taste
What are the 3 main pairs of salivary glands?
Parotid
Submandibular
Sublingual
Where are minor glands typically located?
In the submucosa with short ducts opening directly onto mucosal surface
Structure of parotid glands
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
Where does the parotid duct emerge and where does it go?
Emerges from anterior border
Passes over masseter and pierces buccinator
Empties into oral cavity on a papilla opposite upper second molar tooth
What is the parasympathetic innervation of the parotid gland?
Preganglionic: glossopharyngeal > lesser petrosal nerve > otic ganglion
Postganglionic: otic ganglion > auriculotemporal nerve > parotid gland
Structure of submandibular gland
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
Where does the submandibular duct emerge and where does it go?
Emerges from deep part of gland and passes forward to terminate on the sublingual caruncle near base of lingual frenum
What is the parasympathetic innervation of the submandibular gland?
Preganglionic: facial nerve > chorda tympani > lingual nerve > submandibular ganglion
Postganglionic: submandibular ganglion > submandibular gland
Structure of the sublingual gland
Almond shaped
Sits in sublingual fossa of inner aspect of mandible
Bounded above by oral mucosa, below by mylohyoid and medially by genioglossus
Where does the sublingual duct emerge and where does it go?
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
What is the parasympathetic innervation of the sublingual gland?
(same as submandibular)
Preganglionic: facial nerve > chorda tympani > lingual nerve > submandibular ganglion
Postganglionic: submandibular ganglion > sublingual gland
Properties of the stroma of salivary glands
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
Properties of the parenchyma of salivary glands
Compound tubulo-acinar glands
Secretory elements consist of serous acini, mucous acini and mixed acini
Merocrine secretion
What is merocrine secretion?
Occurs by exocytosis
The membranes surrounding secretory vesicle fuse with cell membrane and discharge their contents to the extracellular space
What are the two types of duct morphology?
Simple - duct is unbranched
Compound - has a branching duct system
What is a tubuloacinar gland?
Secretory tubules or tubules ending in acini
Salivary glands are tubuloacinar glands
What do serous cells secrete?
Thin watery secretion that contains proteins and ions
What do mucous cells secrete?
Mucin - consists of a protein core that is highly decorated with sugar residues and results in a viscous, sticky secretion
Structure of cells of the serous acini
Typically wedge shaped
Prominent nucleus in basal part of cell
Extensive rough endoplasmic reticulum
Granular appearance due to large numbers of apical secretory vesicles
Structure of cells of the mucous acini
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
What is a serous demilune?
Cells of mixed acini appearing as a crescent shaped collection of cells at the end of the secretory unit
Properties of myoepithelial cells
Speciailised epithelial cells for contraction
Form a network around groups of secretory cells and when they contract help to expel secretions from the gland
Where do acinus empty?
Intercalated duct
What makes an intercalated duct?
Cuboidal cells
Where do intercalated ducts empty?
Striated duct
What makes up a striated duct?
Columnar cells with a central nucleus and prominent striations
What are the striations in a striated duct?
Infoldings of the cell membrane accompanied by lines of mitochondria to power the molecular pumps within the membranes
What do molecular pumps do?
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
Where do striated ducts empty?
Excretory ducts within connective tissue between lobules
What lines excretory ducts?
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)
Amounts of each cell type in different glands
Parotid gland - all serous cells
Submandibular gland - mostly serous, some mucous
Sublingual gland - mostly mucous, some serous
What different types of minor glands are there and where are they found?
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
Where are von Ebner’s glands?
Associated with circumvalate and foliate papillae and open into the base of the cleft surrounding the papillae
Are minor glands serous or mucous?
Mostly mucous apart from von Ebners glands which are entirely serous
Function of von Ebner’s glands
Serous secretion helps dissolve food molecules to aid taste
Also keeps cleft flushed to allow for next taste
