Intra-oral surface anatomy

Describe oral cavity

• Extends from lips and cheeks externally to pillar of fauces (sit either side of uvula) internally where it continues into oropharynx

• Vestibule: between lips and cheek

• Oral cavity proper: behind teeth

Describe anatomical components of oral cavity:

• Palate:

  • Forms roof of mouth

  • Separates oral and nasal cavities

• Floor of oral cavity:

  • Consists of mucous membrane covering mylohyoid muscle

  • Occupied mainly by tongue

• Lateral walls:

  • Defined by checks and retromolar region (behind molars)

Primary and secondary functions of mouth

Primary:

• Ingestion of food

• Selection of food

  • Taste buds tell us wether food is good or not

• Mastication

• Swallowing

Secondary:

• Speech

• Ventilation

Describe lips

• Composed of muscle (orbicularis or is) and connective muscle

• Covered externally by skin

• Covered internally by a mucous membrane

• competent: lips lightly closed at rest separated by no more than 3-4mm

• Imcompetent: lips at rest but not sealed or closed

  • Different from conditions where lips are merely held apart habitually (mouth breathers)

Describe oral vestibule

• Narrow space between lips and teeth

• Mucosa covering alveolus is reflected on to lips and cheeks

  • Forms a trough (sulcus) called vestibular fornix

  • Most upper part of oral cavity

  • In some regions of of sulcus, mucosa may show sickle-shaped folds

• All folds contain loose connective tissue

  • Are neither muscle attachments or sites of large blood vessels

• Mouth Open: vestibule and oral cavity directly connected / communicate between the teeth

• Teeth occluded / closed: vestibule is a closed space that communicates with oral cavity only behind last molars

Describe gingivae and alveolar mucosa

• Gingiva

  • Covers upper part of alveolar bone and necks of teeth

  • Appears pale pink

    • More keratinised, further away from blood vessels

  • Delineated from alveolar mucosa via mucogingival junction

• Gingiva subdivided into

  • Attached gingiva

    • Bound to alveolus and teeth

    • May stippled (small bumps due to connective tissue)

  • Free gingiva

    • Lies unattached around cervical region of tooth

• Free gingival groove may be seen between free and attached gingivae

• Alveolar mucosa:

  • Lines lower part of alveolus

  • Loosely attached to periosteum

    • Via diffuse submucosa

  • Appears red

    • Less keratinised, closer to blood vessels

Describe cheeks

• Extend intraorally from labial commissaries to ridge of mucosa

• Overlie the ascending ramus of mandible

• Bound superiority and inferiority by upper and lower vestibular fornices

• Mucosa is nonkeratinised

• Tightly adherent to buccinator muscle

  • Stretched when mouth is open and wrinkled when closed

• Ectopic sebaceous glands with any associated hair follicle may be present in mucosa

  • Called Fordyce spots

Describe palate:

• Forms roof of mouth

• Separates oral and nasal cavities

• Divided into:

  • Immoveable bony hard palate

  • Movable fibrous soft palate

Describe hard palate:

• Immovable, bony, anterior

• Covered by a masticatory, keratinised mucosa

  • Firmly bound to underlying bone

  • Contains some taste buds

  • Contains incisive papillae

    • Structure in front of incisive foramen

• Palatine raphe

  • Ridge running posteriorly down midline

  • Oral mucosa is directly attached to bone without presence of submucosal layer of tissue

• Palatine rugae

  • Elevated ridges in anterior part

  • Radiate transversely from incisive papilla and anterior part of palatine raphe

• Mass of submucosa at junction of palate and alveolus

  • Greater palatine nerve and vessels run alongside

Describe soft palate

• Moveable, fibrous, posterior

• Palatoglossal and palatopharyngeal folds (pillars of fauces)

  • Extend laterally from border of soft palate

  • Cover palatoglossus and palatopharyngeus muscles

• Tonsillar fossa

  • Lies between palatoglossal and palatopharyngeal folds

  • Houses paltine tonsil (lymphoid tissue)

• Uvula

  • Free edge of soft palate

  • In midline

• Fovea palatini

  • Two small pits either side of midline

  • Represent orifices of ducts from minor mucous glands of palate

• Boundary between soft and hard palate is readily palpable (squishable)

  • Distinguishable by change in colour (has a yellowish tint)

Describe floor of mouth

• Small, horseshoe-shaped region above mylohyoid muscle and beneath moveable part of tongue

• Lined by nonkeratinised mucosa

• Lingual frenum:

  • Fold of tissue near base of tongue in midline

  • Extend onto inferior surface of tongue

  • May be cut in infants if too tight

• Sublingual papilla

  • Opening of submandibular salivary ducts into mouth

  • Large centrally positioned protuberance at base of tongue

• Sublingual folds

  • On either side of sublingual papilla

  • Lies on top of submandibular ducts and sublingual salivary glands

Describe the tongue

• Muscular organ

• Base attached to floor of mouth

• Attached to inner surface of mandible near midline

• Supported by hyoid bone

• Functions:

  • Mastication

  • Swallowing

  • Speech

  • Taste

• Inferior surface

  • Faces floor of mouth

  • Covered by thin lining of nonkeratinised mucosa

  • Tightly bound to underlying muscles

  • Deep lingual veins are visible through mucosa

  • Contains frimbraited folds

    • Irregular fringed folds

    • Lie lateral to frenum

• Superior surface

  • May be divided into two

    • Anterior 2/3s (palatal part)

    • Posterior 1/3 (pharyngeal part)

  • Sulus Termalis

    • Junction of palatal and pharyngeal parts

    • Shallow V-shaped groove

  • Foramen caecum

    • Small midline pit

    • Primordial site of development of thyroid gland

  • Palatal part

    • Mainly keratinised

    • Abundance of projections