Oral Cavity Flashcards
what is the oral fissure?
the opening of the mouth
what is the oral cavity?
the space that the mouth opens on to up until it transitions to the oropharynx
what is the oral vestibule?
the space between the cheeks and teeth
what is the oral cavity proper?
the space inside the teeth; where the tongue is
what are the borders of the combined oral cavity?
- superior border - hard and soft palate
- posterior border - oropharyngeal isthmus
- inferior border - mucous membrane covering mylohyoid muscle; occupied mainly by tongue
- anterior border - lip
- lateral walls - cheeks
what is the basic function of the oral mucosa?
provide a useful moist surface
does the oral mucosa contain hair follicles, sweat glands, or sebaceous glands?
- no hair follicles
- sweat glands present
- a few sebaceous glands present
describe the epithelium of the oral mucosa
- stratified squamous, both keratinized (ortho and para) and non-keratinized
- derived from ectoderm
- renewed every 1-2 weeks
describe the lamina propria of the oral mucosa
- underlying connective tissue
- CT papillae interdigitate with epithelial ridges, called “rete pegs”
- contains many lymphocytes in loose aggregates, as well as the tonsils: 3 x 10^9 PMNs daily
- contains small mixed sero/mucous salivary glands
what are rete pegs?
they hold the epithelium to the underlying lamina propria
describe the characteristics of rete pegs found in the lining mucosa vs. masticatory mucosa
- lining mucosa: flatter, rounded rete pegs
- masticatory mucosa: sharper, more pronounced rete pegs
what are the 3 main divisions of the oral mucosa?
- lining mucosa
- masticatory mucosa
- specialized mucosa
describe the lining mucosa
- non-keratinized
- lacks stratum granulosum (lacks keratinhyaline granules)
- cheeks
- inside of lips
- floor of the mouth
- ventral tongue
- soft palate
describe masticatory mucosa
- keratinized
- gingiva
- parts of the dorsum of the tongue
- hard palate
describe specialized mucosa
taste buds on the dorsal and lateral surfaces of the tongue
T or F:
the oral mucosa structure is similar to the rest of the GI tract
false
describe the structure of the general oral mucosa
- generally has a submucosa
- different fromthe rest of the gut
- may or may not attach to bone
- generally lining mucosa
describe the structure of the oral mucoperiosteum
- medial hard palate and attached gingiva
- no submucosa
- robust lamina propria attaches directly to bone
describe orthokeratinized tissue
no nuclei visible in keratin layer
describe parakeratinized tissue
some nuclei retained in keratin layer
describe non-keratinized tissue
no keratin
describe the relationship between orthokeratinized and parakeratinized tissues
they differ based on the presence or absence of nuclei in the keratin layer, but the difference between the two is rarely totally clear cut and they can transition back and forth
what are 4 important layers of the epidermis?
from apical to basal:
- stratum corneum
- stratum granulosum
- stratum spinosum (prickle)
- stratum basale
describe the stratum corneum
- anucleate then acellular layer of stacks (squames) of cross-linked keratin coated with lipid
describe the stratum granulosum
- keratohyalin granules - keratin aggregation
- lamellar granules - lipid coating
- non-keratinized tissues will lack this layer
describe the stratum spinosum
contains desmosomes
describe the stratum basale
stems cells and hemidesmosomes
describe the soft palate
- lining mucosa, so it is not keratinized
- good possibility of finding glandular tissue
- separates the oral and nasal cavities
- nasal side has respiratory epithelium
describe the hard palate
- masticatory epithelium to withstand abrasion
- rete pegs provide strong attachment of epithelium to underlying CT
- lamina propria bound directly to underlying bone
- some glandular tissue may be present in some locations
describe the gingiva
- covers upper part of alveolar bone and necks of teeth
- attached, free/marginal gingiva, and interdental
- mucogingival line delineates the attached gingiva from alveolar mucosa; transition between masticatory and lining mucosa
describe attached, free/marginal, and interdental gingiva
- attached - firmly bound to bone around roots of teeth, stippled (underlying attachment to bone); contains dense CT
- free/marginal - lies unattached around cervical region of teeth
- interdental - the part of gingiva between teeth
describe epithelial changes at the mucogingival junction
- attached gingiva: ortho(para)-keratinized stratified squamous
- alveolar mucosa: non-keratinized
describe transitions other than epithelial changes of the mucogingival junction
- attached gingiva - dense lamina propria, many collagen bundles, attached to bone
- alveolar mucosa - lamina propria is looser with many elastic fibers, which give the mucosa elasticity
are the lips keratinized?
yes
what is the line called where the skin transitions to the lip?
vermillion border which leads to the vermillion zone (actual red part of lip)
describe the histology of the vermillion zone
thinly keratinized stratified squamous epithelium associated with lots of superficial capillaries
what is the mucocutaneous junction?
- aka intermediate zone
- transition from the vermillion zone to the labial mucosa
- it is parakeratinized
describe the labial mucosa
- non keratinized, thick epithelium
- flexible, can withstand stretching
- interface with CT is relatively smooth
describe the composition of cells of the oral mucosa
- 90% keratinocytes
- 10% langerhans cells, merkel cells, and melanocytes
what are langerhans cells?
- migratory cells found in the stratum spinosum
- bind antigens and take them to lymph to present them to T cells
what are merkel cells?
touch receptors which synapse with sensory nerves
what are melanocytes?
- produce melanin
- provide pigmentation
- found in deeper tissues
describe the specialized mucosa of the tongue
- specialized mucosa covers the anterior 2/3 of the dorsal tongue
- contains several types of papilla (specialized epithelial structures): filiform papillae, fungiform papillae, foliate papillae, circumvallate papillae
describe filiform papillae
- make up majority of papillae found in specialized mucosa of the tongue
- no taste buds
- keratinized
- anterior 2/3 of tongue
- provide friction
describe fungiform papillae
- part of specialized mucosa of tongue
- larger than filiform
- mostly found at the tip of the tongue
- nonkeratinized epithelium
- anterior part of tongue
- taste buds on upper surface
describe foliate papillae
- part of specialized mucosa of tongue
- nonkeratinized epithelium
- along the posterior sides of the tongue
- not very prominent in adult humans
- contains taste buds on sides in crypts
describe circumvallate papillae
- part of specialized mucosa of tongue
- along junction of the body and base of the tonsillar area of the tongue (posterior)
- large, only 10-12 of them
- keratinized epithelium
- contains taste buds down in crypts
- Von Ebner’s glands (serous salivary glands) wash out crypts
what are taste buds?
- specialized sensory cells
- barrel shaped structure, composed of a cluster of chemoreceptive spindle cells
- apical ends all terminate just below surface in the taste pit
- taste pit communicates with surface through taste pore
describe the taste function of taste buds
- different tastes come from binding different receptors, which trigger different signaling cascades
- there are no distinct regions for different tastes
what is saliva?
- major secretion of the oral cavity
- lubricates the mouth
- buffering
- digestions
- protection
describe the lubrication function of saliva
mucous secretion
describe the buffering function of saliva
bicarbonate, phosphate ions protect teeth against demineralization
describe salivas role in digestion
begins digestion of carbohydrates - amylase in serous secretion
describe salivas role in protection
washing action for bacteria and sugars, helps prevent infection - secretes lactoferrin, lysozyme, and defensins; transport IgA
what are the 3 main types of salivary glands?
- parotid glands
- submandibular glands
- sublingual glands
- also many minor salivary glands scattered throughout the oral cavity: tongue, palate, lining mucosa, etc.
describe the parotid gland
- largest gland
- mostly serous secretions - alpha amylase
- 25% of volume
- contributes during active salivation
describe submandibular glands
- mixed secretions
- mostly serous but some mucous
- serous - amylase
- mucous - mucin
- located beneath floor of mouth
- 60-67% of volume
- big contribution of passive “background” salivary volume
describe sublingual glands
- mixed secretions
- mostly mucous
- located beneath tongue
- smallest gland
- 3-5% of volume
- mucous capped with serous demilunes
what are salivary glands?
a series of branched ducts, which have secretory, contractile end pieces
describe how saliva gets from the gland to the oral cavity
- saliva is deposited at one end of the salivary gland
- flows through the ducts system (intercalated ducts first, then striated ducts) and is modified at various points
- myoepithelial cells mixed in with secretory cells contract to push the saliva out into the oral cavity
- the end product is hypotonic and contains enzymes and bicarbonate
what are intralobar ducts?
- intercalated ducts and striated ducts
- they are so named because they collect saliva from lobules of the same lobe
describe intercalated ducts
- thin, simple cuboidal epithelium
- associated with acini of the pancreas and salivary glands
describe striated ducts
- large lumen, simple columnar epithelium with central nuclei
- more specific to salivary glands
- modify the saliva by secreting bicarbonate and absorbing Na+ and Cl-
what are interlobular ducts?
- larger than intralobular ducts
- collect saliva from multiple lobes
- can be stratified columnar
- lead to excretory ducts which actually deposit the saliva into the oral cavity
