Oral Cavity Anatomy Notes

ORAL CAVITY: DEFINITIONS AND BOUNDARIES

  • Oral cavity begins at the lips and cheeks and extends posteriorly to the area of the palatine tonsils.
  • Palatine tonsils lie on the sides of the throat between the tonsillar pillars.
  • The oral cavity ends posterior to the tonsillar pillars; beyond that, the oropharynx begins.
  • The respiratory system starts at the nasal cavity and includes the nasal pharynx, oral pharynx, and laryngeal pharynx, then continues to the larynx, trachea, bronchi, and lungs, and on to the esophagus and rest of the digestive system.
  • The digestive system shares a common pathway with the respiratory system between the oral pharynx and laryngeal pharynx.

ORAL CAVITY SECTIONS

  • Two parts of the oral cavity: 22 parts: Vestibule and Oral Cavity Proper.
  • Vestibule: space between the lips or cheeks and the teeth.
  • Oral cavity proper: area surrounded by teeth or alveolar ridges back to palatine tonsils; includes region from the floor of the mouth upward to the hard and soft palates.

VESTIBULE: BOUNDARIES AND STRUCTURES

  • Vestibular anterior border: the lips (labia).
  • Vestibular lateral border: the cheeks (bucca).
  • Vestibular posterior border: the anterior border of the ramus of the mandible, covered with soft tissue.
  • Cheek composition: the buccinator muscle; skin on the outside, mucous membrane on the inside.
  • The buccinator crosses from a lateral position near the corners of the mouth toward a medial position.

VESTIBULE: MUCOSAL FEATURES

  • Mucobuccal or mucolabial fold: mucosa of the lips or cheeks that turns toward the gingival tissue.
  • Alveolar mucosa: movable mucosa lying against the alveolar bone; generally reddish in color due to underlying blood vessels and thin mucosa.
  • Mucogingival junction: where the alveolar mucosa becomes tightly attached to the bone; beginning of the gingiva.

VESTIBULE: ORAL CAVITY BORDERS (SUPERIOR & INFERIOR)

  • Superior/inferior borders defined by maxillary and mandibular mucobuccal folds.
  • The vestibule opens into the oral cavity proper through the mucobuccal folds around teeth.

VESTIBULE: GINGIVA, MUCOSA, AND FRENUMS

  • Parotid papilla, buccal mucosa, labial mucosa presented in context of vestibular anatomy.
  • Maxillary vestibule and mandibular vestibule regions shown around teeth.
  • Attached gingival, interdental gingiva, marginal gingiva described.
  • Maxillary mucogingival junction and alveolar mucosa described.
  • Frenum areas and associated features noted.

VESTIBULE: GINGIVA

  • Normal color of gingiva is pink because the mucosal layer is thicker and blood vessels do not impart as much color.
  • In individuals with darker skin tones, some pigmentation of the gingiva may be evident.

VESTIBULE: FRENUM (1 OF 3)

  • Labial frenum: fold of connective tissue at the midline in the upper and lower lips.
  • Upper frenum is usually more pronounced than the lower.
  • Attachment of the maxillary frenum may extend to the crest of the alveolar ridge or over it.

VESTIBULE: FRENUM (2 OF 3)

  • Diastema: when the maxillary frenum is so firmly attached that erupting central incisors may be pushed slightly aside, creating a space between them.
  • Gingival recession caused by the mandibular labial frenum extending too close to the gingiva and pulling downward on the tissue.

DIASTEMA

  • Example of diastema associated with frenum attachment (illustrated in the material).

RECESSION FROM FRENUM

  • Note on recession patterns related to frenum attachments.

VESTIBULE: FRENUM (3 OF 3)

  • Less well-defined frena are evident in the maxillary and mandibular canine areas, around the mucobuccal fold and in a similar area above it in the maxillary arch.

CORONOID PROCESS AND OTHER CLINICAL MANIFESTATIONS OF THE VESTIBULE

  • Coronoid process: part of the mandible felt when the patient opens wide; located in the posterior-superior part of the vestibule, adjacent to the maxillary third molar area.
  • Alveolar bone loss can occur when teeth are lost.
  • Fordyce granules: misplaced sebaceous glands found in the mucosa of lips, cheeks, and retromolar pad area; appear as yellowish granular structures embedded in mucosa.
  • Exostoses (bone growths) may grow on the buccal cortical plate of the mandible and maxilla; generally seen more often on the mandible than the maxilla.

RUGAE AND INCISIVE STRUCTURES OF THE HARD PALATE

  • Rugae: transverse ridges of epithelial and connective tissue in the anterior hard palate; covered with keratinized epithelium.
  • Incisive papilla: bulge of tissue posterior to central incisors at the midline.
  • Incisive foramen: located behind the incisive papilla; carries nasopalatine nerves and blood vessels.

ORAL CAVITY PROPER: HARD PALATE FORAMINA

  • Greater palatine foramina: two openings in bone on each side, lingual to the maxillary second and third molars; carry nerves and blood vessels to the hard palate.
  • Lesser palatine foramina: carry nerves and blood vessels to the soft palate.
  • Vault of the roof of the mouth and related structures noted (hamular process, medial pterygoid plate).

ORAL CAVITY PROPER: HARD PALATE REGIONS

  • Tissue beneath palatal epithelium varies by region:
    • Midline: connective tissue is thin; palate feels hard and bony.
    • Anterolateral area: connective tissue contains fat cells and is thicker.
    • Posterolateral portion: contains minor salivary glands that secrete mucus.
  • Variation in shape and size: can be wide or narrow; high arch or vault; or flat contours.
  • Torus palatinus: excess bone growth in the midline of the hard palate.

TORUS PALATINUS

  • Maxillary torus palatinus: presence of a bony growth along the midline of the hard palate.

ORAL CAVITY PROPER: LANDMARKS

  • Junction of hard and soft palates forms a double curving line.
  • Posterior nasal spine of the palatine bone is the primary midline landmark.
  • Fovea palatinae: two small depressions located on each side of the spine.

HARD PALATE FACTS AND PALATAL STRUCTURES

  • Additional structures around the palatal area include: incisive papilla, incisive foramen, greater palatine foramen, lesser palatine foramina, hamular process, medial pterygoid plate, posterior nasal spine, vault of the palate, palatine tonsil, and retromolar pad.

ORAL CAVITY PROPER: SOFT PALATE

  • Soft palate stretches back from the hard palate.
  • Uvula: downward projecting structure at the most posterior portion at the midline.
  • Levator veli palatini: primary muscle moving the soft palate; elevates and retracts the soft palate to contact the posterior pharyngeal wall during swallowing and speech.

LATERAL BORDERS OF SOFT PALATE

  • Bounded primarily by teeth and associated mucosa.
  • In the posterior lateral part of the oral cavity, boundary is the palatine tonsil and associated pillars.
  • Posterior pillar (palatopharyngeal arch/fold): prominent fold behind the tonsil, extending from the soft palate downward into the lateral pharyngeal wall.
  • Anterior pillar (palatoglossal arch/fold): immediately in front of the palatine tonsil.
  • Palatopharyngeal and palatoglossal muscles form these folds.

POSTERIOR BORDER OF SOFT PALATE

  • Retromolar pad: small elevation of tissue posterior to the mandibular third molar.

TONSILS AND ORAL PHARYNX EXAMINATION

  • Fauces: the space between the left and right tonsils and their pillars.
  • Exam technique: depressing the tongue and asking the patient to say “ahhh” to enable examination beyond the oral cavity into the pharynx.

STRUCTURES OF THE TONGUE

  • Tongue surfaces and papillae: filiform, fungiform, vallate, rudimentary foliate papillae.
  • Underside (ventral surface) shows numerous blood vessels close to the surface.

PAPILLAE OF THE TONGUE

  • Types: filiform, fungiform, circumvallate, foliate; and the rudimentary foliate papillae are present.
  • Visuals include the lingual, palatine, and lingual tonsils in proximity.

TONGUE AND FLOOR OF MOUTH (1 OF 4)

  • Lingual frenum (lingual frenulum): fold of tissue extending from near the tip of the tongue to the floor of the mouth.
  • If the frenulum attaches too close to the tip, tongue mobility can be limited.

TONGUE AND FLOOR OF MOUTH (2 OF 4)

  • Sublingual caruncle: small elevation at the base of the lingual frenulum; opening for ducts of the two major salivary glands, the submandibular and sublingual glands.
  • Sublingual fold: fold of tissue extending from the sublingual caruncle back along the floor of the mouth on either side.

SUBLINGUAL REGION

  • Duct openings of the sublingual salivary gland can be found along the anterior and middle parts of the sublingual fold.
  • Mandibular tori: bony swellings often occurring on the lingual surface of the mandible in the canine area.

TONGUE AND FLOOR OF MOUTH (3 OF 4)

  • Sublingual region features summarized above; focus on ducts and anatomy.

SUBLINGUAL FOLD AND CARUNCLE

  • Lingual torus and mandibular torus noted as bony protuberances in respective regions.

TONGUE AND FLOOR OF MOUTH (4 OF 4)

  • Floor of the mouth is supported by paired mylohyoid muscles forming a sling from the mylohyoid line on one side of the mandible to the other.
  • Contraction raises the tongue and floor of the mouth.
  • Oral tissue beneath the tongue is extremely thin and sensitive to trauma.

OTHER CLINICAL MANIFESTATIONS OF THE ORAL CAVITY

  • Clinical roles: all personnel viewing intraoral anatomy should be aware of normal anatomy; dentists bear primary responsibility for diagnosis and treatment, but every team member should note abnormalities.

ORAL CONDITIONS SHOWN AS EXAMPLES

  • Pseudomembranous Candidiasis (Thrush) as an oral manifestation.
  • GERD as an oral manifestation.
  • Sjögren’s Syndrome as an oral manifestation.

QUESTIONS (REVIEW)

  • What are the two parts of the oral cavity? What are the boundaries of each part?

SUMMARY ANSWERS (KEY POINTS)

  • The oral cavity can be separated into the vestibule and the oral cavity proper.
  • Vestibule borders: anteriorly by the lips, laterally by the cheeks, superiorly/inferiorly by the maxillary/mandibular mucobuccal folds, and posteriorly by the buccal-alveolar tissues, gingiva, and teeth.
  • The oral cavity proper extends superiorly from the roof of the mouth to the floor of the mouth; laterally bounded by the alveolar bone, teeth, and gingiva; posteriorly by the palatine tonsils, anterior and posterior pillars, and fauces.

ADDITIONAL NOTES AND REFERENCES

  • Frenum attachments and diastema implications are clinically important when assessing spacing and gingival health.
  • Alveolar mucosa vs gingiva color differences relate to tissue thickness and vascular visibility.
  • Retromolar pad and posterior structures important in evaluating posterior oral cavity regions.
  • Exam techniques for pharyngeal exposure (depressing tongue, say "ahhh").
  • Palatal landmarks (posterior nasal spine, fovea palatinae) assist in locating foramina and nerve pathways.
  • Awareness of common oral manifestations (candidiasis, GERD, Sjögren’s syndrome) aids in broader health assessment.

KEY TERMS TO KNOW

  • Vestibule, Oral Cavity Proper, Mucobuccal Fold, Mucolabial Fold, Alveolar Mucosa, Gingiva, Mucogingival Junction, Exostoses, Torus Palatinus, Torus Mandibularis, Lingual Frenum, Sublingual Caruncle, Sublingual Fold, Mylohyoid Muscle, Retromolar Pad, Incisive Papilla, Incisive Foramen, Greater Palatine Foramen, Lesser Palatine Foramen, Palatine Tonsil, Fauces, Uvula, Levator Veli Palatini, Palatoglossal Arch, Palatopharyngeal Arch, Coronoid Process, Fordyce Granules, Pseudomembranous Candidiasis, Sjögren’s Syndrome, GERD

QUOTABLE FIGURES AND STRUCTURES

  • Greater Palatine Foramina: two openings in bone on each side, lingual to 2nd and 3rd maxillary molars; carry nerves and vessels to the hard palate.

  • Lesser Palatine Foramina: carry nerves and vessels to the soft palate.

  • Incisive Foramen: behind the incisive papilla; carries nasopalatine nerves and vessels.

  • Fovea Palatinae: two small depressions on each side of the posterior nasal spine.

  • Hard palate regions: midline/thin connective tissue; anterolateral thicker; posterolateral with minor salivary glands.

  • Torus Palatinus: midline bony growth on the hard palate.

  • Retromolar Pad: tissue elevation posterior to the mandibular third molar.

  • Fordyce Granules: ectopic sebaceous glands in mucosa.

  • Exostoses (exotoses): bony growths on buccal cortical plates.

    • 22 parts; 11 of 33 sections; etc. where applicable to indicate categorical counts in the original text.