Mouth Cavity

Mouth Cavity
The oral cavity is divided into
  • Outer vestibule
  • Inner large oral cavity proper
The vestibule of mouth is a narrow space bounded
  • Externally by lips & cheeks
  • Internally by teeth & gums
The parotid gland opens on the inner surface of the cheek in the vestibule opposite the crown of the upper 2nd molar tooth.

Oral Cavity Proper Boundary
  • Anterolaterally by teeth
  • Posteriorly by oropharynx
  • Roof by hard & soft palate
  • Floor by tongue
Content of the oral cavity:
1) Tongue with papillae
2) Teeth
3) Lingual tonsil
4) Palatine mucus gland
5) Opening of the ducts of sublingual, submandibular & parotid gland
 
Oropharyngeal isthmus:
The junction between the oral cavity proper and oropharynx
Bounded
  • Superiorly by the soft palate
  • Inferior by the posterior part of the tongue
  • On each side palatoglossal arches
Nasopharyngeal/ Pharyngeal isthmus:
The junction between nasopharynx and oropharynx

Notes: Tonsillar fossa is bounded by anteriorly by palatoglossal arch & posteriorly by palatopharyngeal arch

Opening of 3 Pairs of Salivary Glands:
  • On each side of the frenulum of the tongue, there is a sublingual fold.
    On the medial end of the sublingual fold, it shows elevation called sublingual papillae, where duct of submandibular gland open
  • Similarly, the edge of the sublingual fold has the opening for sublingual gland
  • The parotid gland opens on in the vestibule opposite the crown of the upper 2nd molar tooth.


Teeth:

Parts of teeth-
  • Root
  • Neck
  • Crown, projecting above the gum
Deciduous teeth- 20 in number
Permanent teeth- 32 in number

Teeth in each half of the jaw:
  • 2 incisors
  • 1 canine
  • 2 premolars
  • 3 molars
Nerve supply of teeth
  • Upper teeth and upper jaw
    By branches of superior alveolar nerves, branch of the maxillary nerve, which is the branch of the trigeminal nerve
    That’s why correlation with its nerve supply, pain from upper jaw and teeth are referred to the skin over maxilla, lower eyelid

  • Lower teeth and lower jaw
    By inferior alveolar nerve, branch of the mandibular division of the trigeminal nerve
Clinical correlation:
1) Stomatitis is inflammation/ ulceration around the mouth
     It can be subdivided into
  • Cheilitis - inflammation around the lip
  • Glossitis means inflammation of the tongue
  • Gingivitis means inflammation of the gum
  • Pharyngitis means inflammation around the back of the mouth
    (esp.oropharynx)
2) In scurvy (caused by the deficiency of vitamin C), the gums are swollen and spongy and bleed on touch.

3) In gingivitis, the edges of the gums are red and bleed easily.

4) Due to correlation with its nerve supply (maxillary nerve), pain from the upper jaw and teeth is referred to as the skin over maxilla, lower eyelid.