Oral Cavity Flashcards

Oral Cavity

Oral Cavity Definition

• The oral cavity begins at the lips and cheeks and extends posteriorly to the palatine tonsils.

• The palatine tonsils are located on the sides of the throat between the tonsillar pillars.

• The oral cavity ends posterior to the tonsillar pillars, where the oral pharynx begins.

• The digestive system and respiratory system share a common pathway between the oral pharynx and laryngeal pharynx.

• The digestive system continues to the esophagus, while the respiratory system continues to the larynx, trachea, bronchi, and lungs.

Oral Cavity Sections

The oral cavity consists of two parts:

• Vestibule: The space between the lips or cheeks and the teeth.

• Oral cavity proper: The area surrounded by the teeth or alveolar ridges, extending back to the palatine tonsils; includes the region from the floor of the mouth upward to the hard and soft palates.

Vestibule

Borders

• Anterior border: The lips (labia).

• Lateral border: The cheeks (bucca).

• Posterior border: The anterior border of the ramus of the mandible, covered with soft tissue.

• The cheek is mainly formed by the buccinator muscle, covered with skin on the outside and mucous membrane on the inside.

• The buccinator muscle extends back from the corners of the mouth to join the muscles of the upper throat wall.

• The zygomaticoalveolar crest is a ridge of bone at the upper posterior vestibular space, marking the beginning of the anterior part of the zygomatic arch (cheekbone).

• Superior/Inferior Borders:

  • Mucobuccal or mucolabial fold: The mucosa of the lips or cheeks that turns toward the gingival tissue.

  • Alveolar mucosa: Movable mucosa lying against the alveolar bone, generally reddish due to underlying blood vessels.

  • Mucogingival junction: The point where the alveolar mucosa becomes tightly attached to the bone, marking the beginning of the gingiva.

Lips

• The lips are the junction between the skin of the face and the mucosa of the oral cavity.

• The vermilion zone is a transitional zone of reddish tissue between these two areas.

• The philtrum is the indentation at the midline on the skin of the upper lip, derived from the embryonic medial nasal processes.

Gingiva

• The normal color of the gingiva is pink due to the thickness of the mucosal layer and reduced visibility of blood vessels.

• Patients with darker skin may exhibit pigmentation of the gingiva.

Frenum

• The labial frenum is a fold of connective tissue at the midline in the upper and lower lips.

• The upper frenum is typically more pronounced than the lower frenum.

• The attachment of the maxillary frenum may extend to the crest of the alveolar ridge or over it.

• Diastema: A space between the erupting central incisors may occur if the maxillary frenum is firmly attached.

• Gingival recession can be caused by the mandibular labial frenum extending too close to the gingiva and pulling downward on the tissue.

Other Clinical Manifestations

• Coronoid process: A part of the mandible that can be palpated when the patient opens wide; located in the posterior-superior part of the vestibule, adjacent to the maxillary third molar area.

• Alveolar bone loss: Loss of alveolar bone can occur after teeth are lost.

• Fordyce granules: Misplaced sebaceous glands in the mucosa of the lips, cheeks, and retromolar pad area; appear as yellowish granular structures embedded in the mucosa.

• Exostoses: Bony growths on the buccal cortical plate of the mandible and maxillae, more often seen on the mandible than the maxilla.

Oral Cavity Proper: Hard Palate

Features

• Rugae: Transverse ridges of epithelial and connective tissue in the anterior hard palate, covered with keratinized epithelium.

• Incisive papilla: A bulge of tissue posterior to the central incisors at the midline.

• Incisive foramen: Located under the incisive papilla; carries nasopalatine nerves and blood vessels.

• Greater palatine foramina: Two openings in the bone on each side, lingual to the second and third maxillary molars; carry nerves and blood vessels to the hard palate.

• Lesser palatine foramen: Carry nerves and blood vessels to the soft palate.

Regions

• The tissue beneath the palatal epithelium varies from region to region.

• Midline: Connective tissue is thin, and the palate feels hard and bony.

• Anterolateral area: Connective tissue contains fat cells and is thicker.

• Posterolateral portion: Contains minor salivary glands that secrete mucus.

Variations

• The shape and size of the hard palate vary among individuals. It may be wide or narrow, have a high, arching curvature or vault, or be flat in its contours.

• Torus palatinus: Excess bone growth that can occur in the midline of the hard palate.

Landmarks

• The junction of the hard and soft palates forms a double-curving line.

• The posterior nasal spine of the palatine bone is the primary landmark at the midline.

• Fovea palatinae: Two small depressions located on each side of the spine.

Oral Cavity Proper: Soft Palate

• The soft palate stretches back from the hard palate.

• Uvula: A downward projecting muscle at the most posterior portion at the midline.

• Levator veli palatini muscle: Performs soft palate movement by pulling the soft palate up and back until it contacts the posterior throat (pharyngeal) wall.

Lateral Borders

• Primarily bounded by teeth and associated mucosa.

• In the posterior lateral part of the oral cavity, the boundary is the palatine tonsil and associated pillars.

• Posterior pillar (palatopharyngeal arch or fold): A prominent fold behind the tonsil, extending from the soft palate downward into the lateral pharyngeal wall.

• Anterior pillar (palatoglossal arch or fold): Immediately in front of the palatine tonsil.

• The palatopharyngeal and palatoglossal muscles form these folds.

Posterior Borders

• 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.

• Depressing the tongue and asking the patient to say “ahhh” enables examination beyond the oral cavity into the pharynx.

Structures of the Tongue

• Filiform papillae

• Fungiform papillae

• Vallate papillae

• Rudimentary foliate papillae

• The underside or ventral side of the tongue shows many blood vessels close to the surface.

Tongue and Floor of Mouth

• Lingual frenum or frenulum: A fold of tissue extending from near the tip of the tongue down to the floor of the mouth.

• If the frenum is attached close to the tip of the tongue, the tongue will have limited movement.

• Sublingual caruncle: A small elevation on each side at the base of the lingual frenum.

  • This is the opening for ducts of two of the major salivary glands, the submandibular and sublingual glands.

• Sublingual fold: A fold of tissue extending from the sublingual caruncle back along the floor of the mouth on either side.

• Small openings of ducts of the sublingual salivary gland can be found along the anterior and middle parts of the sublingual fold.

• Mandibular tori: Bony swellings on the lingual surface of the mandible at the canine area often occur.

• The floor of the mouth is supported by paired mylohyoid muscles, which form a sling from the mylohyoid line on one side of the medial surface of the mandible to the same line on the other side.

• Contraction of these muscles raises the tongue and floor of the mouth.

• Oral tissue beneath the tongue is one of the thinnest in the oral cavity and therefore sensitive to trauma.

Other Clinical Manifestations of the Oral Cavity

• Problems in other parts of the body may manifest in the oral cavity.

• All who view the intraoral anatomy are responsible for being aware of normal anatomy, including dental assistants, laboratory technologists, dental hygienists, and dentists.

• Legally, dentists bear primary responsibility for diagnosis and treatment, but every member of the team should note anything abnormal.