Oral Mucosa Anatomy Quiz

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Questions and Answers

What causes the vermilion border to be prone to dehydration and cracking?

It is continuously exposed to moisture from saliva.

It lacks hair follicles, sebaceous, and sweat glands. (correct)

It contains a thick layer of keratinized epithelium.

It has an abundance of sebaceous glands.

Why does the vermilion border appear reddish in living tissue?

Because of sweat glands beneath the surface.

From the presence of numerous blood vessels. (correct)

As a result of moisture retained from saliva.

Due to a dense layer of keratin.

What is NOT a component of the oral mucous membrane?

Non-keratinized stratified squamous epithelium.

Minor salivary glands of mucous type.

A layer of hair follicles. (correct)

Lamina propria.

What type of connective tissue is present in the lamina propria of the oral mucosa?

Dense irregular connective tissue. Signup and view all the answers

Which structure is responsible for the high sensitivity of the vermilion border?

Rich sensory innervations. Signup and view all the answers

What anatomical feature separates the epithelium from the connective tissue in the oral mucosa?

Basement membrane. Signup and view all the answers

What is a characteristic of the epithelial layer of the oral mucosa?

It forms ridges that protrude towards the lamina propria. Signup and view all the answers

Which of the following best describes the oral mucosa compared to the cutaneous portion?

It has a smooth outline and is non-keratinized. Signup and view all the answers

What are ameloblasts primarily responsible for secreting?

Enamel matrix Signup and view all the answers

Which structure do ameloblasts primarily form after finishing enamel synthesis?

Protective epithelium Signup and view all the answers

What is the composition of enamel rods primarily made of?

Hydroxyapatite crystals Signup and view all the answers

What is the significance of Tomes' process in ameloblasts?

It contains secretory granules for enamel matrix formation. Signup and view all the answers

How does the arrangement of enamel rods affect their properties?

It provides stability to the enamel structure. Signup and view all the answers

What occurs to ameloblasts during tooth eruption?

They degenerate completely. Signup and view all the answers

Which cells secrete the matrix that initiates enamel formation?

Ameloblasts Signup and view all the answers

What type of tissue is found in the pulp cavity?

Soft connective tissue Signup and view all the answers

What covers the crown of a tooth in young individuals?

Enamel Signup and view all the answers

What is the main substance that composes the bulk of a tooth?

Dentin Signup and view all the answers

Which portion of the tooth contains the pulp cavity?

Root Signup and view all the answers

What mineral primarily constitutes the inorganic portion of dentin?

Calcium hydroxyapatite Signup and view all the answers

What type of cells produce the organic matrix of dentin?

Odontoblasts Signup and view all the answers

Which part of a tooth is referred to as the neck?

The constricted region between crown and roots Signup and view all the answers

What connects the tooth to the alveolar bone?

Periodontal ligament Signup and view all the answers

What is the apical foramen associated with?

Entrance and exit of blood vessels Signup and view all the answers

What type of nerve fibers are associated with odontoblast processes?

Unmyelinated nerve fibers Signup and view all the answers

Which sensory modality is exclusively perceived in teeth?

Pain Signup and view all the answers

According to the hydrodynamic theory, what triggers stimulation of nerve fibers near odontoblast processes?

Movement of fluids inside dentinal tubules Signup and view all the answers

Which of the following distinguishes dentine from bone?

Higher mineralization level Signup and view all the answers

What initiates the synthesis of dentin components in adult teeth?

Destruction of the enamel Signup and view all the answers

What is the primary inorganic component of enamel?

Calcium hydroxyapatite Signup and view all the answers

Which ions can be incorporated into enamel during its synthesis?

Strontium and lead Signup and view all the answers

What enhances the resistance of enamel to acidic dissolution?

Fluorapatite formation Signup and view all the answers

What type of epithelium lines the upper (nasal) surface of the soft palate?

Pseudostratified columnar epithelium Signup and view all the answers

Which type of glands are referred to as palatal glands?

Accessory minor salivary glands of mucous type Signup and view all the answers

What is the primary function of the tongue in the oral cavity?

Speech and food manipulation Signup and view all the answers

How is the dorsal surface of the tongue characterized?

Irregular and rough Signup and view all the answers

What anatomical feature separates the anterior and posterior two thirds of the tongue?

V-shaped groove known as the terminal sulcus Signup and view all the answers

Which surface of the tongue is considered the ventral surface?

The lower surface Signup and view all the answers

The foramen cecum in the tongue marks what anatomical significance?

The embryonic origin of the thyroid gland Signup and view all the answers

What characterizes the lamina propria of the soft palate?

It is infiltrated with lymphocytes Signup and view all the answers

What are the main components of dental pulp?

Odontoblasts, fibroblasts, and mesenchymal cells Signup and view all the answers

Which part of the dental pulp is described as the upper, expanded coronary portion?

Pulp chamber Signup and view all the answers

What kind of connective tissue is the dental pulp primarily classified as?

Loose gelatinous mucoid connective tissue Signup and view all the answers

What tissue covers the dentin of the root in teeth?

Cementum Signup and view all the answers

Where do blood vessels and nerve fibers enter the pulp cavity?

Apical foramen Signup and view all the answers

Which cells are responsible for forming cementum?

Cementoblasts Signup and view all the answers

What is unique about the blood supply of cementum compared to bone?

Cementum lacks Haversian systems and blood vessels Signup and view all the answers

Which type of nerve fibers extend into dentinal tubules and are sensitive to pain?

Myelinated nerve fibers Signup and view all the answers

Study Notes

Digestive System Histology

The digestive system comprises oral cavity (oral histology), alimentary tract (GIT), and accessory glands
GIT extends from oral cavity to anus, including pharynx, esophagus, stomach, small intestine, and large intestine
Accessory glands include major salivary glands (parotid, submandibular, and sublingual), liver, gallbladder, and pancreas

Oral Cavity

Extends from lips and cheeks to pillars of the fauces, continuing into oropharynx.
Includes anterior and sidewalls, roof, and floor.
Subdivided into oral cavity proper and vestibule, communicating posteriorly behind the last molar (wisdom) tooth.
Oral vestibule is a slit-like space between lips/cheeks and gums/teeth. Receives opening of parotid duct opposite the second upper molar tooth.
Oral cavity proper extends from inside of teeth/gingivae to oropharyngeal isthmus, leading to oropharynx
Functions: Ingestion of food, mastication & swallowing, speech and ventilation.
Contents: Tongue, teeth, and minor/accessory salivary glands.

Boundaries of Oral Cavity

Anteriorly: Lips
Sidewalls: Cheeks externally, gums and teeth internally
Roof: Hard palate anteriorly, soft palate posteriorly
Floor: Mylohyoid muscle covered by oral mucosa, occupied mainly by the tongue, lined with thin epithelium (stratified squamous nonkeratinized)

Lips

Fleshy folds forming anterior boundary of oral cavity.
Normally, competent lips are lightly closed at rest, forming an oral seal.
Attached to respective gingiva via frenulum.
Each lip has a central bulk of skeletal muscle (orbicularis oris), covered by mucosa internally and hairy skin externally.

Lip Layers

Cutaneous portion: Thin hairy skin, keratinized stratified squamous epithelium, containing hair follicles, sebaceous, and sweat glands.
Red (Vermilion) border/Transition zone: Very thin, lightly keratinized stratified squamous epithelium and rich microvasculature giving it color.
Mucous portion (internal surface): Smooth oral mucous membrane, non-keratinized stratified squamous epithelium, and compact lamina propria housing minor salivary glands (labial glands).

Cheeks

Forms the external side wall of the oral cavity.
Extend intraorally from labial commissures anteriorly to the ridge of mucosa overlying the ascending ramus of the mandible posteriorly.
Bound superiorly by upper and lower vestibular sulci.
Composed of mainly buccinator muscle covered by mucosa on both surfaces.
Outer/external surface (cutaneous portion): Thin hairy skin, keratinized stratified squamous epithelium, sweat glands, sebaceous glands, and hair follicles.
Inner/oral surface (mucous portion): Lined by oral mucosa.

Palates

Soft palate: Forms posterior 1/3 of the palate, consists of a thick bundle of striated muscles, covered by thick mucosa on both surfaces.
- Lined by oral mucosa composed of thick, non-keratinized stratified squamous epithelium, lamina propria with lymphocytes, minor salivary glands (palatal glands), and taste buds.
Hard palate: Anterior 2/3 of the palate, bony structure formed by palatine processes of maxillae and horizontal plates of palatine bone.
- Covered by thin mucosa on both surfaces, with non-keratinized stratified squamous epithelium and dense fibrous lamina propria devoid of glands.

Tongue

Major oral cavity structure for speech, food manipulation, and sensory perception.
Pyramidal muscular organ with wide base (root) and narrow apex (tip), dorsal and ventral surfaces.
Placed horizontally in the oral cavity in anterior–posterior axis, central bulk of striated muscle covered by oral mucosa.
Variable structure by region, specialized for food manipulation, general sensory reception, and special visceral sensory function of taste.
- Dorsum surface is irregular and rough, with multiple papillae types (filiform, fungiform, foliate, and vallate) for taste.

Tongue Papillae

Filiform: Numerous, short, conical, bristle-like projections covering most of the anterior two-thirds of the tongue, highly keratinized, resist abrasion, and assist mastication and movement of food.
Fungiform: Mushroom-shaped, wider than filiform, found among filiform papillae, containing taste buds
Foliate: Leaf-shaped elevations located along the posterior lateral margins of the tongue, have folds/grooves containing taste buds
Vallate (Circumvallate): Large, arranged in a V-shaped row at the posterior end of the tongue, deeper grooves, containing many taste buds.

Tongue Posterior One Third

Contains lingual tonsils, roughened by masses of lymphoid nodules separated by shallow grooves (tonsillar crypts).
Contains lingual papillae types, varying in structure and function
Papillae have connective tissue cores (lamina propria), covered in stratified squamous epithelium, keratinized in some like filiform.

Pulp Cavity

Soft connective tissue-filled space within the tooth, surrounded by dentin.
Richly vascularized and contains sensory nerve fibers responsible for pain sensation in the central nervous system (CNS).
Organized odontoblasts arranged at the periphery
Two portions: • Pulp chamber: The upper, expanded coronary portion • Root canal (root portion): A narrow portion extending to the apex of the root, ending at the apical foramen

Cementum

Calcified tissue covering the root dentin.
Thin layer secreted by cementoblasts that is similar in composition and calcification to bone but lacks Haversian systems and blood vessels.
Thicker in the apical region of the root, housing cementocytes (cells resembling osteocytes).
Nourishment occurs through the periodontal ligament.

Periodontal Ligament

Dense fibrous connective tissue within the tooth socket.
Collagen fibers attach to cementum and alveolar bone.
Supports the tooth, facilitates some movement within the socket, and protects the bone from excessive pressure during chewing.
Contains blood vessels and nerves.

Alveolar Bone

Bone in immediate contact with periodontal ligament, serves as its periosteum.
- Immature bone (primary bone) with collagen fibers not arranged in typical lamellar pattern.
- Many collagen bundles from periodontal ligament penetrate and bind this bone to cementum.
Forms tooth sockets around the roots of teeth.
- Perforating vessels and nerves pass through to supply the tooth.

Gingiva

Specialized mucous membrane firmly bound to the periosteum of the maxillae and mandible
composed of keratinized stratified sq epithelium and a lamina propria rich in connective tissue papillae.
Junctional epithelium: Specialized part bound to enamel by a cuticle resembling a thick basal lamina, forming the epithelial attachment (Gottlieb).
Epithelial cells are attached via hemidesmosomes to this cuticle.
Gingival sulcus/crevice: Deepening or groove up to 3mm surrounding the crown between enamel and epithelium.

Tooth Development

Occurs in four main stages (bud, cap, bell, and root development)
Enamel of the tooth develops from epithelial (ectodermal) origin while dentin, cementum, pulp, periodontal ligament and alveolar bone originate from mesenchymal (mesodermal) tissue.

Histodifferentiation (Tooth)

In the bud stage, enamel organs are located at periphery, polygonal cells in center.
In the cap stage, enamel organ becomes cap-shaped, with mesenchymal cells condensing to create dental papilla. -Cells from the concave face of the enamel organ differentiate into ameloblasts (responsible for enamel production), and cells on the dental papilla start to differentiate into odontoblasts (dentin producing cells).
In the bell stage, the shape of the crown is formed by inner dental epithelium folding.

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Description

Test your knowledge on the anatomy and physiology of the oral mucosa, focusing on the vermilion border and its characteristics. This quiz covers components, connective tissue types, and sensory structures within the oral cavity. Enhance your understanding of oral health and structure through these key questions.