Oral Cavity

Oral Cavity: Basics - Grand Entrance Tour

• Definition: First part of the digestive system; involved in ingestion, mastication, and initial digestion (salivary amylase).

• Extent: From lips anteriorly to oropharyngeal isthmus posteriorly.

• Boundaries:

  • Roof: Hard palate (anterior 2/3), soft palate (posterior 1/3).
  • Floor: Mylohyoid muscle, geniohyoid muscle, tongue.
  • Lateral: Cheeks (buccinator muscle).
  • Anterior: Lips (orbicularis oris muscle).
  • Posterior: Oropharyngeal isthmus (palatoglossal arches).

• Subdivisions:

  • Oral Vestibule: Space between lips/cheeks externally & teeth/gums internally.
    • Parotid duct (Stensen's duct) opens opposite upper 2nd molar.
  • Oral Cavity Proper: Space enclosed by dental arches.
    • Contains tongue, openings of submandibular (Wharton's) & sublingual ducts.

⭐ Clinical Pearl: The submandibular duct (Wharton's duct) opens at the sublingual caruncle, lateral to the lingual frenulum. It is the most common site for salivary calculi (sialolithiasis).

Tongue & Palate - Taste-Talk Titans

• Tongue: For taste, speech, swallowing.

  • Parts: Oral (Ant. 2/3), Pharyngeal (Post. 1/3).
  • Papillae: Filiform (no taste buds), Fungiform, Foliate, Circumvallate (8-12 large, V-shape, taste buds).
  • Muscles (Motor):
    • Intrinsic (shape): Sup/Inf Longitudinal, Transverse, Vertical. All CN XII.
    • Extrinsic (position): Genioglossus, Hyoglossus, Styloglossus. All CN XII.
    • Palatoglossus: 📌 CN X (Pharyngeal Plexus).
  • Innervation (Sensory):
    • Ant. 2/3: General - Lingual N. (CN V3); Taste - Chorda Tympani (CN VII).
    • Post. 1/3: General & Taste - Glossopharyngeal N. (CN IX).
    • Root/Epiglottis: Vagus N. (CN X).
  • Blood Supply: Lingual Artery (from ECA).

• Palate: Roof of mouth.

  • Hard Palate (Ant.): Maxilla (palatine process), Palatine bone (horizontal plate). Innervation (Sensory): Greater Palatine N. & Nasopalatine N. (CN V2).
  • Soft Palate (Post. - Velum): Mobile, muscular; closes nasopharynx.
    • Muscles: Tensor Veli Palatini (📌 CN V3); Levator Veli Palatini, Palatoglossus, Palatopharyngeus, Musculus Uvulae (all CN X via Pharyngeal Plexus).
    • Innervation (Sensory): Lesser Palatine N. (CN V2).

⭐ All intrinsic and extrinsic muscles of the tongue are supplied by the hypoglossal nerve (CN XII), except for palatoglossus, which is supplied by the pharyngeal plexus (CN X).

Floor, Glands & Nerves - Oral Cavity Utilities

• Floor of Mouth:
  • Muscles: Mylohyoid (diaphragm), Geniohyoid, Ant. Digastric.
  • Sublingual space: Sublingual gland, Wharton's duct, lingual n., hypoglossal n. (CN XII).
• Major Salivary Glands: 📌 Parasympathetic: CN VII (Chorda Tympani via Submandibular ganglion) for SubMandibular/SubLingual; CN IX (Otic ganglion) for Parotid.
  • Parotid: Largest, serous. Stensen's duct (opens opp. Upper 2nd Molar).
    • 
  • Submandibular: Mixed (serous > mucous). Wharton's duct (opens at sublingual caruncle).

    ⭐ Submandibular gland is the most common site for sialolithiasis (~80% of cases).

  • Sublingual: Smallest, predominantly mucous. Ducts of Rivinus (multiple, on sublingual fold); main duct is Bartholin's duct.
• Nerves of Oral Cavity:
  • Sensory (General):
    • CN V2 (Maxillary): Palate, upper teeth/gingiva.
    • CN V3 (Mandibular): Lingual n. (Gen. sense ant. 2/3 tongue, floor of mouth), Inf. alveolar n. (lower teeth/gingiva), Buccal n. (cheek mucosa).
    • CN IX (Glossopharyngeal): Gen. sense & taste post. 1/3 tongue, oropharynx.
  • Sensory (Special - Taste):
    • CN VII (Chorda tympani via Lingual n.): Ant. 2/3 tongue.
    • CN IX: Post. 1/3 tongue (also general sensation).
  • Motor:
    • CN XII (Hypoglossal): All intrinsic & extrinsic tongue muscles (excl. Palatoglossus - CN X via pharyngeal plexus).
    • CN V3 (Mandibular): Muscles of mastication, Mylohyoid, Ant. belly of Digastric.
    • CN VII (Facial): Buccinator, Orbicularis oris (muscles of facial expression contributing to oral vestibule).

High‑Yield Points - ⚡ Biggest Takeaways

• Tongue muscles: CN XII (Hypoglossal), except Palatoglossus by CN X (Vagus).
• Taste: Anterior 2/3 by Chorda tympani (VII); Posterior 1/3 by Glossopharyngeal (IX).
• General Sensation (Tongue): Anterior 2/3 by Lingual nerve (V3); Posterior 1/3 by CN IX.
• Parotid duct (Stensen's) opens opposite upper second molar.
• Submandibular duct (Wharton's) opens at sublingual caruncle.
• Lingual artery (from ECA) is the primary blood supply to the tongue.
• Tongue tip lymph drains bilaterally to submental nodes; posterior 1/3 to deep cervical nodes.