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Oral cavity & oropharynx

General

Anatomy & histology

Author: Charu Thakral, M.D.

Last author update: 1 January 2013

Last staff update: 29 January 2024

Copyright: 2002-2024, PathologyOutlines.com, Inc.

PubMed Search: Normal anatomy oral cavity

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Cite this page: Thakral C. Anatomy & histology. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/oralcavitynormalanatomy.html. Accessed April 19th, 2024.

Anatomy

Oral cavity extends anteriorly from vermilion junction of lips to junction of hard and soft palate above and to line of circumvallate papillae on dorsal tongue below; communicates freely with oropharynx posteriorly
Oral cavity contains buccal mucosa, maxillary and mandibular arches, retromolar trigone, anterior two - thirds of tongue, floor of mouth and hard palate
Dorsal tongue: villous, normally exposed surface; contains papillae and specialized taste receptors
Ventral tongue: nonvillous, undersurface
Anterior two - thirds of tongue (oral tongue): freely mobile portion of tongue that extends anteriorly from line of circumvallate papillae to undersurface of tongue at junction of floor of mouth; composed of skeletal muscle, includes 4 areas: tip, lateral borders, dorsum and undersurface (nonvillous ventral surface of tongue)
Base of tongue (posterior one - third of tongue): bound anteriorly by circumvallate papillae, laterally by glossotonsillar sulci and posteriorly by epiglottis
Buccal mucosa: all of membrane lining inner surface of cheeks and lips from line of contact of opposing lips to line of attachment of mucosa of alveolar ridge (upper and lower) and pterygomandibular raphe; contains ostia of main duct of parotid gland (Stenson duct)
Floor of mouth: semilunar space of myelohyoid and hyoglossus muscles, extending from inner surface of lower alveolar ridge to undersurface of tongue; posterior boundary is base of anterior pillar of tonsil; divided into two sides by frenulum of tongue, contains ostia of submaxillary and sublingual salivary glands
Gingiva: mucosa in area of teeth and palate; extends from labial sulcus and buccal sulcus to a cuff of tissue around each tooth
Hard palate: forms roof of oral cavity; semilunar surface between upper alveolar ridge and mucous membrane covering palatine process of maxillary palatine bones; extends from inner surface of superior alveolar ridge to posterior edge of palatine bone
Lip: begins at junction of vermilion border (mucocutaneous junction) with skin, includes only vermilion surface or that portion of lip that comes into contact with opposing lip; upper and lower lip are joined at commissures of mouth; external surface is skin and mucous membrane; internally contains orbicularis oris muscle, blood vessels, nerves, areolar tissue, fat and small labial glands; inner surface of lip is connected to gum in midline by frenulum, a mucous membrane fold
Lower alveolar ridge: mucosa overlying alveolar process of mandible which extends from line of attachment of mucosa in lower gingivobuccal sulcus to line of free mucosa of floor of mouth; posteriorly extends to ascending ramus of mandible
Retromolar gingiva (retromolar trigone): mucosa overlying ascending ramus of mandible from level of posterior surface of last molar tooth to apex superiorly, adjacent to tuberosity of maxilla
Tonsillar area: anterior and posterior tonsillar pillars and tonsillar fossa
Upper alveolar ridge: mucosa overlying alveolar process of maxilla which extends from line of attachment of mucosa in upper gingivobuccal sulcus to junction of hard palate; posterior margin is upper end of pterygopalatine arch
Vermillion border: mucocutaneous junction of lip

Juxtaoral organ of Chievitz

Not actually a congenital anomaly but normal occurring neuroepithelial structure called organ of Chievitz, Chievitz paraparotid organ, juxtaoral organ or epithelial nests
Reported in 56% of adult autopsies without oral mucosal lesions
Within intraoral sensory nerve
May undergo nodular hyperplasia
Located bilaterally in buccotemporal fascia on medial surface of mandible, near angle
Rare examples of proliferative / hamartomatous masses of juxtaoral organ reported
May be interpreted as squamous cell carcinoma, mucoepidermoid carcinoma or metastasis especially during frozen sections (Am J Surg Pathol 1979;3:147)

Microscopic (histologic) description

Multilobulated nests of squamous-like epithelium without keratin formation, occasionally with lumen lined by cuboidal cells
Associated with small nerves and resembling perineural invasion

Case reports

Child with intraoral tumor (Int J Oral Maxillofac Surg 2003;32:101)
63 year old man with rare hamartomatous lesion (J Clin Pathol 2003;56:789)

Histology-oral cavity

Stratified squamous epithelium often with parakeratosis
No hair follicles or sweat glands present
Keratinization in areas most exposed to mastication (gingiva, hard palate, dorsum of tongue)
Lamina propria contains loose connective tissue, mucous glands, serous minor salivary type glands
Submucosa has dense collagenous fibrous tissue
Oral tongue mucosa: modified keratinized squamous epithelium with small papillae; papillae can be filiform (majority, conical projections of keratinized epithelium), fungiform (rounded elevations, nonkeratinized), foliate (along sides of tongue) or cirucumvallate (at junction of anterior 2/3 and posterior 1/3 tongue, largest papillae)
Taste buds: barrel shaped, lightly staining, intramucosal sensory receptors present in large numbers on circumvallate papillae and in lesser numbers elsewhere
Intraepithelial nonkeratinocytes: melanocytes (basal), Merkel cells (basal), Langerhans cells (suprabasal) and lymphocytes occur in oral mucosa
Ectopic sebaceous glands (Fordyce spots) increase with age in adults
Tonsillectomy specimens frequently contain skeletal muscle (Hum Pathol 2000;31:813)

Immunostains