This document provides information on barium studies used to examine the gastrointestinal tract, including barium swallow, barium meal, barium follow through, and barium enema. It describes the anatomy of the esophagus and locations of esophageal constriction. It discusses indications, contraindications, and techniques for various barium studies and how they are used to diagnose conditions like esophageal webs, Achalasia, hiatal hernia, gastric ulcer, and colorectal cancer. Radiographic images demonstrate abnormalities seen on barium exams.