Oral Mucosa Anatomy Quiz

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.

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.