Esophagus

• Flat, muscular tube that connects pharynx to stomach


  esophagus
• Upper esophageal sphincter relaxes to allow


  movement into esophagus
• Peristalsis moves bolus through


  esophagus
• Lower esophageal sphincter relaxes to allow


  entry into stomach - fails when gastroesophageal reflux disease (GERD) occurs
• Mucosa contains


  non - keratinized stratified squamous epithelium - protects against friction from food moving through esophagus
• Muscularis varies in composition throughout the


  esophagus
• Skeletal muscle


  upper third
• Combination of skeletal and smooth muscle


  middle third
• Smooth muscle


  lower third
• Outer adventitia due to


  esophagus located outside of abdominal cavity