1. The Oral Cavity Flashcards
What are the general histological features/features of the oral cavity? What kind of epithelium?
STRATIFIED SQUAMOUS EPITHELIUM Lips Rest of oral cavity- minor salivary glands (seromucous glands) Teeth Tongue Major Salivary Glands
What is the difference between the lip, vermillion border and the tongue?
The LIP:
- Hair follicles
- Stratified squamous KERATINISED epithelium
VERMILLION BORDER
- No glands
- No hair follicles
- Blood vessels
TONGUE
- Statified squamous NON KERATINISED epithelium; this is normally not keratinised but can become para keratinised with excessive wear and tear.
- Skeletal muscle arranged at right angles
- Numerous seromucous glands are often embedded between the muscle fibres.
- Skeletal muscle - orbicularis oris.
What is the histological difference bewtween the anterior 1/3 and posterior 1/3 of the tongue?
Anterior 1/3 lacks the MALT thatthe posterior 1/3 is famous for.
What are the papillae on the surface of the tongue?
What separates anterior 2/3 from posterior 1/3?
Anterior to posterior:
- Filiform papillae
- Fungiform
- Foliate
- Circumvillate
The ANTERIOR 2/3 of the tongue is separated fromt he posterior third by the SULCUS TERMINALIS- which is where the circumvillae papillae lie
Which papillae are Gutatory?
Circumvallate, Foliate, Fungiform
Circumvillate: V shaped line of around 9 (4-18) papillae anterior ot the sulcus terminalis
They contain about half of all taste buds
Von Ebners Glands associated with them and the FOliate Papillae - (serous only)
Supplied by CN9 (glossopharyngeal n)
Foliate:
Found bilaterally along posterolateral margins of the tongue
Contain about 1/4 of all tast buds
Supplied by CN9, and CN12 (hypoglossal)
Fungiform:
Found over most of the surface. Contain 1/4 of tast buds (some may contain no taste buds at all). Supplied by CN9, CN12.
Taste Buds
What are the 5 modalities to human taste perception?
Gustatory Papillae: circumvillate, fungiform & Foliate
There are 5 modalities to human taste perception:
- Sour
- Salt
- Bitterness
- Sweetness
- Imami - monosodium glutamate.
All taste buds have a similar structure, with taste receptor cells having a lifespan of only around 10 days before being replaced (olfactory region 30 days)
Extralingual taste buds can also be found- palate, uvulva, oesopahgus, epiglottus
Which nerve supplies (taste) Posterior 1/3 of tongue?
Which nerve/s supply taste afferents for anterior 2/3 or tongue
Which nerve supplies taste posterior to the pharynx
- GLOSSOPHARYNGEAL CN9
- CN 7
- CNX (vagus)
Explain the structure and function of Von Ebners Glands
Found at the base of the circumvallate and foliate papillae crypts.
They are SEROUS secreting minor salivary glands that produce lingual lipase.
Their secretion also helps to act as the liquid milieu in which taste can be detected.
Important in washing away taste molecules so new taste can be detected
What are the embryological structures from which teeth are derived?
ENAMEL/ DENTAL LAMINA: from ECTODERM
Dentin, cemetum, pulp and periodontal ligament from the MESODERM (mesenchyme)
Explain the development of a TOOTH!!
The DENTAL LAMINA (4 of these) appears at 6 WEEKS
Each DENTAL LAMINA gives rise initially to 4 ENAMEL ORGANS (enamil organs will develop into central and lateral incisors, the canines and the first molar teeth- all deciduous)
The enamel organ develops an epithelial layer of enamel producing cells - AMELOBLASTS
Later in development the DENTAL LAMINA will develop posteriorly and give rise to further enamel organs for the rest of the molar teeth (one more deciduous molar and the 3 permanent molars)
The deciduous teeth are eventually lost and replaced by permanent teeth which develop adjacent to the deciduous ones.
The MESENCHYME immediately adjacent to he enamel organ condenses to form the DENTAL PAPILLA. This stage (because of its shape) is called the CAP STAGE
The dental papilla develops a layer of DENTIN producing cells called ODONTOBLASTS
As the enamel organ develops further it assumes a shape which is referred to as the bell shape. At this stage the formation of the dentine and then enamel, has begun between the two epithelial layers.
Tooth eruption is caused by growth (elongation of th tooth)
Explain the structure of the mature tooth!
Enamel; Dentin; Odontoplasts (still present); dentin
Crown; Neck and Root.
ODONTOBLASTS- the cell
A DENTINAL TUBULE- contains the odontoblast apical process. Walls of the tubule are formed by alligned collagen fibres. At the end of the tubule, the bifurcated end extends into the enamel.
DENTIN consists of 2-% organic material (mainly TYPE I COLLAGEN) and 80% inorganic material (cyrstals of hydroxyaatitie and fluoroapatite)
PREDENTIN is the non mineralised zone surrounding the apical processes of the odontoblast. It contains type I collagen resulting from the released procollagen processed into tropocollagen.
Ameloblasts the cell
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What is Amelogenesis Imperfecta?
No or imperfect formation of enamel during tooth development
- 3 main genes identified, depending o nthe gene, may demonstrate autosomal dominant or autosomal recessive or X-linked inheritance
- Teeth are unusually small, discoloured, pitted or grooved nd prone to rapid wear and breakage.
Salivary Glands- what are the salivary glands emptying into the mouth via ducts?
Parotid Salivary Glands: Serous secretion- anterior to ears, empties near upper teath
SUBMANDIBULAR Salivary Glands: 80% serous, 20% mucous
SUBLINGUAL Salivary Glands: 80% mucous
