Anatomy of Oral Cavity in a Nutshell

Anatomy of Oral Cavity in a Nutshell

Location & boundaries:

• Space between lips: Rima Oris (entrance to oral cavity) & isthmus of the oropharynx  (entrance of the oropharynx)
• Boundaries: vague, blends with temple and orbit
• Parts of the oral cavity:
  1. Vestibule: area on the Buccal (toward cheek) side of the teeth/gums (between cheeks/lips and the teeth/gums)
  2. Oral Cavity Proper: area on the lingual (toward the tongue) side of the teeth/gums (bounded inferiorly by palate,  anteriorly/laterally by dental arches & inferiorly by the muscular diaphragm which forms the floor of mouth) & communicating with the pharynx through the isthmus of the oropharynx

1. 1. • Tongue fills most of this area when the mouth is closed

• • • Floor or the oral cavity: The Sublingual fossa
    • Arches between oral cavity and oropharynx
      1. Anterior: palatoglossal arch (covers the palatoglossus muscle)
      2. Posterior: palatopharyngeal arch (covers the palatopharyngeus muscle)
      3. Between these arches: find the tonsil bed with the palatine tonsil.
         • Tonsil Bed:
           1. Contains the tonsil branch of the facial artery
           2. Innervated by the glossopharyngeal nerve (CN IX)

​​

​1-Frenulum of the upper lip; 2-Gum; 3-Upper lip; 4-Hard palate; 5-Soft palate;
6-Uvula; 7-Palatoglossal arch; 8-Palatopharyngeal arch; 9-Palatine tonsil;
10-Fauces; 11-Dorsum of tongue; 12-Lower lip; 13-Frenulum of the lower lip

Lips:

1. 1. Composed of skin on the outside
   2. The red portion = Vermillion portion
   3. The interior aspect is covered with a mucous membrane.
   4. The Vermillion border is the boundary between the outer skin portion of the lips and the red Vermillion portion of the lips.
   5. Are attached to superior/inferior gums by Labial Frenulum of upper / lower lips.
   6. Innervation:

1. 1. 1. Upper lip = V2 (Infraorbital Branch)
      2. Lower lip = V3 (Mental Branch)

Filtrum:

• Shallow groove beneath the nose, part of the upper lip

1. 1. Is derived from frontonasal prominence.
   2. Involved in cleft lips

Cheeks:

• Skin Innervation:
  1. V2 (infraorbital)- sensory
  2. V3 ( Long Buccal)- sensory
• Deeply, find Buccinator
  1. Attaches corner of the lip
  2. Innervated by Facial’s Buccal branch (CN VII)
• Lined by mucous membrane Innervated by V3 long Buccal nerve
• Parotid Papilla:
  1. The parotid duct pierces the Buccinator and then it has a projection that goes into the vestibule of the oral cavity adjacent to the 2^nd upper molar.
  2. The parotid papilla is the end of the parotid duct as it pushes into the mucous membrane to empty saliva into the vestibule.

Teeth:

• Upper teeth
  • Innervation by V2 (Maxillary)
    1. Infra-orbital nerve
    2. Posterior superior alveolar nerve
    3. Anterior superior alveolar nerve
    4. Sometimes a middle superior alveolar nerve
    5. These branches run along the maxillary sinus
• Lower teeth: Innervation by V3 Inferior alveolar nerve- comes out as mental nerve

Gums:

• Also called Gingivae
• Fibrous connective tissue covered with the oral mucous membrane.
• Maxillary / Mandibular gingivae
• 2 types of gums
  1. Alveolar: Part that sticks up between the teeth &  unattached
  2. Gingivae proper: The Dense CT is applied directly to the bone (mandible or maxilla) & attached portion
• External surface (buccal side)
  1. See superior alveolar nerve (V2) innervation of the upper external surface
  2. See Buccal nerve for the lower external surface
• Internal surface (lingual)
  1. Greater palatine and nasopalatine nerve for upper internal surface
  2. Lingual nerve for lower internal surface

Oral diaphragm: Suprahyoid Muscles

• Innervations:
  1. Stylohyoid- CN VII
  2. Mylohyoid- V3 nerve to mylohyoid
  3. Genoihyoid- C 1
  4. Digastric
     • Anterior – V3
     • Posterior- CN VII
• Actions of the suprahyoid muscles:
  1. Can work on both the floor of the oral cavity and on the hyoid bone
  2. Can elevate the hyoid- when they elevate the hyoid, they elevate the larynx.
  3. When they elevate the hyoid, they also elevate the floor of the oral cavity→ elevates the tongue as well.
  4. If the hyoid bone is fixed, these muscles depress the mandible
  5. They also act in concert with the infrahyoid muscles to fix the hyoid bone.

Also read:

1. The Oral Cavity @ TeachMeAnatomy
2. Practice Anatomy tests for free!
3. Best Anatomy books for Medical students
4. Best Anatomy websites & journals
5. New Anatomy syllabus (CBME) in India
6. Topographic Anatomy syllabus in Russia
7. Regional Anatomy syllabus in China

Also Watch:

• Anatomy of the oral cavity @ Osmosis

• Anatomy of the oral cavity & pharynx @ Lecturio