ANATOMY OF ORAL CAVITY

ORAL CAVITY

• The oral cavity (mouth) is the 1st part of the digestive system.
• Functions: Ingestion, mastication (chewing), digestion (enzymatic), speech, and respiration.

BOUNDARIES OF THE ORAL CAVITY
• Roof – Formed by the hard palate (anterior) and soft palate (posterior).
• Floor – Formed by the tongue and muscles.
• Lateral Walls – Cheeks, containing the buccinator muscle.
• Anterior Boundary – Lips (Labia).
• Posterior Boundary – Oropharyngeal isthmus (opening into the oropharynx).

DIVISIONS OF THE ORAL CAVITY
• Oral Vestibule – Space between the lips, cheeks, and teeth.
• Oral Cavity Proper – Main cavity behind the teeth, where the tongue and salivary glands are located.

STRUCTURES WITHIN THE ORAL CAVITY
• Teeth (Dentition)
o Functions: Chewing (mastication).
o Types:
           Incisors (cutting) – 2 per quadrant.
           Canines (tearing) – 1 per quadrant.
           Premolars (grinding) – 2 per quadrant.
           Molars (grinding) – 3 per quadrant (third molar = wisdom tooth).
  Total: 32 permanent teeth (adult), 20 primary teeth (children).

• Tongue
o Muscular organ essential for speech, taste, and swallowing.
o Divided into:
        Anterior 2/3 (oral part) → Taste via chorda tympani (CN VII - Facial nerve).
        Posterior 1/3 (pharyngeal part) → Taste via glossopharyngeal nerve (CN IX).
o Covered with papillae (taste buds):
         Filiform – Most numerous, no taste buds.
         Fungiform – Taste buds present.
         Circumvallate – Large, at the back, taste buds present.
         Foliate – Lateral margins, taste buds present.

SALIVARY GLANDS
• Secrete saliva for digestion & lubrication.
• Three major salivary glands:
o Parotid gland → Largest, secretes into the vestibule (via Stensen’s duct).
o Submandibular gland → Secretes into the floor of the mouth (via Wharton’s duct).
o Sublingual gland → Smallest, secretes via multiple small ducts.

HARD AND SOFT PALATE
• Hard palate (bony) – Forms the anterior roof of the mouth.
• Soft palate (muscular) – Ends in the uvula, prevents food from entering the nasal cavity.

BLOOD SUPPLY
• Arterial:
      o Branches of external carotid artery (facial, lingual, maxillary arteries).
• Venous:
      o Drains into the internal jugular vein.

NERVE SUPPLY
• Motor:
      o Tongue muscles – Hypoglossal nerve (CN XII).
      o Soft palate & pharynx – Vagus nerve (CN X).
• Sensory:
o Anterior 2/3 tongue – Trigeminal nerve (CN V, mandibular division).
o Taste sensation:
            Anterior 2/3 – Facial nerve (CN VII).
            Posterior 1/3 – Glossopharyngeal nerve (CN IX).

CLINICAL CORRELATIONS
• Cleft Palate
     o Failure of palatal shelves to fuse, leading to an opening between the oral and nasal cavities.
• Dental Caries (Cavities)
     o Tooth decay due to bacterial infection.
• Tongue Disorders
     o Glossitis – Inflammation of the tongue.
     o Ankyloglossia (Tongue-tie) – Short lingual frenulum, affecting speech & feeding.
• Salivary Gland Disorders
      o Sialolithiasis – Salivary stones blocking ducts (especially in submandibular gland).
      o Mumps – Viral infection causing parotid gland swelling.