Anatomy of the Oral Cavity and Pharynx

Boundaries and areas

• The oral cavity is bounded anteriorly by the lips, laterally by the cheeks, superiorly by the hard palate, and inferiorly by the mucosa covering the tongue and the sheet of muscles covering the mandible.
  • Contain teeth, tongue, salivary glands
• The pharynx is bounded by the mouth anteriorly, the soft palate superiorly, the posterior tongue inferiorly, and the pharyngeal constrictors posteriorly
  • Can be divided into 3 parts:
    • Nasopharyx (lies posterosuperiorly to the soft palate, behind the nasal cavity)
    • Oropharynx (extends from the level of the soft palate to the level of the hyoid bone
    • Laryngopharyx or Hypopharynx (extends from the level of the hyoid bone behind the larynx to the upper end of the oesophagus at the lower border of the cricoid cartilage)
      • Piriform Fossa
        • Recess on each side of the larynx bounded by the aryepiglottic fold medially and thyroid cartilage/thyrohyoid membrane laterally
          • It is a common place for food etc to become trapped in people with dysphagia
      • Postcricoid area
      • Posterior Pharyngeal wall

Muscles of the Pharynx

• 2 layers of muscles
  • Circular constrictor muscles (superior, middle and inferior)
    • Act to propel food bolus down
  • Longitudinal muscles
    • Palatopharygeus muscle (origin- palatine aponeurosis/hard palate; insertion- thyroid cartilage; innervation- pharyngeal branch of CNX; supple- facial artery)
    • Stylopharygeus muscle (origin- styloid process; insertion- thyroid cartilage; innervation- glossopharyngeal CNIX)
      • Act to lift the pharynx/larynx during swallowing to prevent food entering the nasopharyx and airways

Lymph nodes/tissues

•  Nasopharygeal tonsil (between the roof and the posterior wall of the nasopharynx- often disappears in childhood- hypertrophy is often referred to as adenoids)
• Tonsils
  • 2 prominent masses situated one on either side between the glossopalatin and pharyngopalatine arches