Anatomy of the Oral Cavity

Overview of the Digestive System

• Begins with the Oral Cavity
  • Triggers salivation (e.g., thinking of food like a cheesecake)
• Followed by the Pharynx
• Esophagus to the Stomach
• Small Intestine: Duodenum, Jejunum, Ileum
• Large Intestine: Caecum, Colon, Rectum
• Accessory Structures:
  • Teeth, Tongue, Salivary glands
  • Liver, Gallbladder, Pancreas

External Structures of the Mouth

• Lips: Upper lip, Lower lip, Oral angle/labial commissure
• Grooves:
  • Nasolabial Sulcus (beside the lips)
  • Philtrum (middle above lips)
  • Mentolabial Sulcus (below lips)
• Muscle: Orbicularis Oris Muscle
  • Controls the Oral fissure/Rima Oris

Division of the Oral Cavity

• Oral Vestibule: Focus of this lecture
  • External Borders: Lips and Cheeks
  • Internal Borders: Teeth and Gums
• Oral Cavity Proper: To be covered in the next lecture

Anatomy of the Oral Vestibule

Lips

• Epithelium: Different types cover inner and outer sides
• Frenulum (Upper and Lower): Attaches lips to gums
• Labial Glands: Minor salivary glands in the mucosa

Cheeks (Buccae)

• Buccinator Muscle: Shapes the cheek
• Buccopharyngeal Fascia: Covers buccinator and extends behind pharynx
• Buccal Fat Pad (Bichat’s Fat Pad): Gives cheek appearance
• Tunica Mucosa: Mucous membrane on the inner side
  • Parotid Duct Opening: Includes Papilla of the parotid duct

Teeth

• Structure:
  • Crown: Visible part
  • Root: Embedded in dental alveolus
  • Neck: Transition between crown and root, covered by gums
• Periodontium: Supports the root's fixation (gomphosis - dentoalveolar joint)
• Pulp Cavity: Contains dental pulp, continues as root canal
• Dentine: Basic substance
  • Crown covered by Enamel
  • Neck/Root covered by Cementum
• Periodontal Ligament: Surrounds cementum

Types of Teeth

• Milk Teeth (20): Appear ~6 months to 24 months
• Permanent Teeth (32): Replace milk teeth, include wisdom teeth
• Teeth Arrangement:
  • Incisors (1,2): 8 total
  • Canine (3): 4 total
  • Premolars (4,5): Absent in milk teeth
  • Molars (6,7,8): Include wisdom teeth

Gums (Gingiva)

• Composition: Dense fibrous tissue
• Alveolar Mucosa: Mobile, covers root level
• Gum Proper: Immobile, covers neck and crown level
• Anatomical Divisions:
  • Gingival Papillae: Between necks of teeth
  • Gingival Margin: Elevated around tooth
  • Gingival Sulcus: Between gum margin and tooth

Next Step

• Continue with Oral Cavity Proper in the next lecture.