ORAL CAVITY

• The oral cavity is lined with moist stratified squamous epithelium, which protects against abrasion.
• 2 divisions of the oral cavity:

  • Vestibule - space between lips/cheeks and the teeth
  • Oral cavity proper - lies medial to the teeth
• Lips (labia) - muscular structures formed by orbicularis oris muscle and connective tissue
• Cheeks - form lateral walls of the oral cavity

  Substance of cheek:

  • Buccinator muscle - flatten the cheek against the teeth
  • Buccal fat pad - rounds out side profile of the face
• Palate - roof of the oral cavity; separates the oral and nasal cavity

  2 parts:

  • Hard palate - anterior bony part
  • Soft palate - posterior nonbony part
• Uvula - posterior projection from the soft palate
• Fauces - posterior boundary of oral cavity, opening into the pharynx
• Palatine tonsils - located in the lateral wall of the fauces
• Tongue - large, muscular organ that occupies most of the oral cavity when closed
• Lingual frenulum - connects the tongue to the floor of the mouth
• Muscles of the tongue:

  • Intrinsic muscles - within the tongue itself
  • Extrinsic muscles - outside the tongue but attached to it
• Terminal sulcus - divides the tongue into two parts

  • Anterior to terminal sulcus - covered by papillae, some of which containing taste buds
  • Posterior to terminal sulcus - lingual tonsil
• Adults normally have 32 teeth, which are distributed in two dental arches:

  • Maxillary arch
  • Mandibular arch
• The teeth in each quadrant include:

  • Central and lateral incisor
  • Canine
  • First and second premolars
  • First to third molars
• Wisdom teeth - third molars, appear in late teens or early twenties

  Embedded wisdom teeth are referred to as impacted, and is surgically removed due to it causing pain and irritation
• Permanent teeth (secondary teeth) - teeth of the adult mouth; replacements for deciduous teeth (primary or milk teeth)
• Each tooth consists of:

  • Crown
  • Neck
  • Root
• Dental caries (tooth decay) - breakdown of enamel by bacterial acids on the tooth surface
• Periodontal disease - inflammation and degradation of the periodontal ligaments, gingiva, and alveolar bone; most common cause of tooth loss in adults
• Gingivitis - inflammation of the gingiva (gums)
• Halitosis - bad breath
• Salivary Glands:

  Large salivary glands in the oral cavity:

  • Parotid glands - largest salivary gland; produces watery saliva
  • Submandibular glands
  • Sublingual glands - smallest

  Small salivary glands:

  • Lingual glands
  • Palatine glands
  • Buccal glands
  • Labial glands
• Saliva - combination of serous and mucous secretions by the salivary glands
• The parotid and submandibular glands secrete 1-1.5 L of saliva per day.
• Mucin - a proteoglycan that gives a lubricating quality to the secretions of salivary glands
• Saliva contains lysozyme, which contains IgA and has a weak antibacterial action
• The serous part of saliva contains a digestive enzyme called salivary amylase.