Oral Cavity and GI Track Flashcards
Parts of the Oral Cavity
- Oral cavity proper
- hard and soft palates superiorly
- tongue/floor of mouth inferiorly
- entrance to oropharynx posteriorly
- Vestibule
- space sperating lips and cheeks from alveolar ridges and teeth
- Tongue
- Salivary glands
- Tonsils
- Teeth, periodontal ligament, and gingiva
Oral Cavity
Lining
-
Lining mucosa is non-keratinized
- Vestibule
- Floor of the mouth
- Underside of the tongue
- Cheeks
-
Masticatory mucosa either keratinized or parakeratinzied
- gingiva
- parts of the hard palate
-
Parakeratinized epithelium
- similar to keratinized
- surface cells have visible pyknotic nuclei
Tongue
Anterior portion is free.
- Inferior surface covered by minimally keratinized stratified squamous
-
Superior surface has two seperate regions seperated by the sulcus terminalis
-
Anterior 2/3
- covered by lingual papillae
- Covered by varying stratified squamous epithelium
- 4 types:
- Filiform
- Fungiform
- Vallate
- Foliate
- covered by lingual papillae
-
Posterior 1/3
- more irregular due to lingual tonsils
-
Anterior 2/3
Posterior portion is anchored to the floor of the mouth and hyoid bone.
Bulk of the tongue is formed of interlaced bundles of skeletal muscles.
- Some arise outside of the tongue → extrinsic muscles
- Some completely contained within the tongue → intrinsic muscles
-
Bundles of adipose tissues seperates muscle bundles
- Allows greater mobility
Lingual Papillae
Distribution
Filiform Papillae
- Most numerous
- Thin, conical shape curved posteriorly
- Covered with maximally keratinized stratified squamous epithelium
- No taste buds
Fungiform Papillae
- Narrow bases and slightly rounded top
- Covered with very thinly keratinized stratified squamous
- Less numerous and slightly taller than filiform papillae
- Scattered among them
- Numerous underlying capillary loops gives redder tint
- Taste buds on dorsal surface
Circumvallate Papillae
- Located in V-shaped line just anterior to sulcus terminalis
- Fewer in number (6-12)
- Covered in stratified squamous which may be keratinized
- Largest lingual papillae
- Surrounded by a deep sulcus or valley
- Ducts of serous von Ebner glands open into sulci
- Have ~ 250 taste buds located on the sides of each papilla
Foliate Papillae
- Located on posterolateral aspect of tongue
- Covered in minimally keratinized stratified squamous
- Appears as vertical ridges seperated by furrows
- Few taste buds
- Serous glands open into sulci between the papillae
Taste Buds
- Most located on fungiform or vallate papillae
- Clusters of 60-80 elogated cells
- Large at bases forming ovoid body
- Narrow superficial ends of cells converge around a taste pore
- Cell types:
- basal cells → stem cells
- neuroepithelial cells
- supporting cells
Salivary Glands
Major salivary glands:
Parotid, Sublingual, Submandibular
Minor salivary glands:
Lingual, Labial, Buccal, Molar, Palatine
- Compound tubuloacinar glands
- Secretory cells organized into acini → lobules → lobes
- Serous, Mucous, or Mixed
- Intercalated duct → intralobular duct → striated duct → interlobular duct
Parotid Glands
- Serous only
- Produces 30% salivary volume
Inset → Serous acinar at higher magnification.
Submandibular Glands
-
Mixed glands
- Mostly serous acini
- Some mucous acini with serous demilunes
- Producse 60% of salivary output
- Short intercalated ducts
- Long striated ducts
Left inset → mucous acini with serous demilune
Right inset → striated duct
Sublingual Glands
- Mostly mucous
- May have some serous demilunes
- No pure serous acini
- Intercalated & striated ducts short
Inset → serous demilune
Tonsils
General
- Aggregates of lymphoid tissues
- Encircles oral cavity and pharynx
- Forms the tonsillar (Waldeyer’s) ring
- Often has significant lymphocytic infiltration
Lingual Tonsils
- Embedded in the dorsal surface of posterior 1/3 of tongue
- Numerous
- Luminal surface covered by minimally keratinized stratified squamous epithelium
- Each tonsil has a single shallow crypt
- Parenchyma composed of lymphoid tissue
- Mostly secondary nodules with germinal centers
- Thin capule seperates deep surface of each tonsil from CT of tongue mucosa
Palatine Tonsils
- Paired tonsils, one on each side of opening from oral cavity to oropharynx
- Minimally keratinized stratified squamous
- Each tonsil has 10-20 deep, branching crypts
- Parenchyma of mostly secondary nodules
- Seperated from underlying tissue by dense CT capsule
Pharyngeal Tonsil
- Unpaired pharyngeal tonsil
- Located in roof of nasal pharynx
- Called adenoids when enlarged or inflammed
- Covered by pseudostratified columnar epithelium with patches of stratified squamous
- Surface with folds or pleats
Dental Formula
The number and types of teeth in each quadrant of mouth.
(incisor, canine, premolar, molar)
Adult: 32 teeth with dental formula 2:1:2:3
Deciduous dentition: 20 teeth with dental formula 2:1:2
Parts of a Tooth
-
Crown
- Projects above gum line
- Dentin covered by enamel
- Cusps - raised ridges at the occlusal surface
-
Root
- Part below gum line
- Holds tooth in alveolus
- Dentin covered by cementum
-
Neck (Cervix)
- Where crown and root meet at cemento-enamel junction (CEJ)
-
Pulp
- Internal part of tooth
- CT with blood vessels, lymphatics, and nerves
- Enter at apical foramen
- Houses odontoblasts
- Important in formation of dentin
-
Periodontal Ligament
- Extends from cementum to periosteum of alveolar bone
- Holds tooth in body socket
Enamel
-
Dense calcified material
- 95% inorganic material
- NO collagen
- Proteins involved in mineralization process
- Covers crown of tooth
- Avascular & acellular after eruption
- Cannot be repaired
- Deposited as elongated rods
- Extends thickness of enamel layer from dentin-enamel junction to external surface
- Formed by Ameloblasts
Dentin
- Forms bulk of tooth
- Covered by:
- enamel in the crown
- cementum in the root
- Avascular
- Maintains nerve suppy inside dentinal tubule
- Similar composition to bone but more mineralized
- Secreted by Odontoblasts
Cementum
- Calcified external covering of tooth root
- Derived from dental sac (dental follicle)
- Similar but less mineralized than bone
- Formed by cementoblasts → cementocytes
-
Cellular cementum
- cementocytes housed in lacunae
- communicate through canaliculi
-
Acellular cementum
- found closest to junction with enamel or dentin
- Continuous production of cementum throughout life
- Reasorbed by odontoclasts
- during exfoliation process
- due to trauma