Lecture Notes: The Pharynx and the Esophagus

Overview

• Chapter 17, Section 4: Focus on the pharynx and the esophagus.
• Both play vital roles in the process of swallowing.

Pharynx

• Location: Cavity posterior to the mouth, extends from nasal passage to esophagus.
• Parts of the Pharynx:
  • Nasopharynx: Posterior to nasal cavity, contains openings to auditory tubes.
  • Oropharynx: Posterior to the oral cavity, involved in air and food passage.
  • Laryngeal pharynx: Posterior to the larynx, pathway to esophagus.

Esophagus

• Length: Approximately 10 inches (25 cm) from pharynx to stomach.
• Structure: Tubular organ with mucous glands in submucosa to moisten and lubricate.
• Muscular Layers:
  • Superior (upper third)
  • Middle (middle third)
  • Inferior (lower third)
• Function: Involved in swallowing, using peristaltic action to move food.

Swallowing Mechanism

1. Voluntary Stage: Deciding to swallow, mixing saliva with chewed food to form a bolus.
2. Swallowing Process:
   • Soft palate elevates to block nasal cavity.
   • Hyoid bone and larynx elevate; epiglottis closes over the larynx.
   • Constriction of superior muscles, folding of epiglottis over trachea opening.
3. Peristalsis:
   • Lower part involves peristaltic waves moving bolus through the esophagus.
   • Esophageal Hiatus: Penetrates diaphragm at esophageal hiatus.

Cardiac Sphincter

• Location: Top of the stomach.
• Function: Circular muscle preventing gastric juices from entering the esophagus.
• Relevance: Issues like gastric reflux disease can cause esophageal lesions.

Conclusion

• Covered the pharynx and esophagus, preparing to move into the study of the stomach.