23.5 Pharynx and Esophagus

Food passes from mouth into

oropharynx and then into laryngopharynx

• Allows passage of food, fluids, and air

• Stratified squamous epithelium lining with mucus-producing glands

• Alternating skeletal muscle layers 

• Flat muscular tube that runs from laryngopharynx to

• stomach

• Is collapsed when not involved in food propulsion

• Gastroesophageal (cardiac) sphincter

surrounds cardial orifice where esophagus joins stomach

• Keeps orifice closed when food is not being swallowed

• Mucus cells on both sides of sphincter help protect esophagus from acid reflux

Pierces diaphragm at —— to join stomach

esophageal hiatus

Pharynx and esophagus are conduits to

pass food from mouth to stomach

Major function of both organs (Pharynx and esophagus) is propulsion that starts with

deglutition (swallowing)

• Deglutition involves coordination of 22 muscle groups and two phases:

• Buccal phase: voluntary contraction of tongue

• Pharyngeal-esophageal phase: involuntary phase that primarily involves vagus nerve 

  • Controlled by swallowing center in medulla and lower pons