<prompt> Bird beak appearance on barium swallow is feature of?Achalasia cardiaDiffuse esophageal spasmCaustic strictureCarcinoma of the esophagus  <response>: Ans. A. Achalasia cardia. Harrisons Medicine, 18th ch. 292; Fig. 292-5.Achalasia cardia- Megaesophagussigmoid esophagus- Bird beak deformity- Absence of primary peristalsis below level of cricopharyngeus- Hurst phenomenon temporary transit through cardia when hydrostatic pressure of barium column is above toxic LES pressure- Vigorous achalasia numerous tertiary contractions in non-dilated distal esophagus of early achalasia.Hiatus hernia- Epiphrenic bulge- 4 longitudinal coarse thick gastric folds above gastroesophageal junction or in the suprahiatal pouch- A Schatzki or B ring if present, is pathognomonic of a hiatal hernia because it marks the junction between squamous and columnar epithelium and represents the Z line.- Distance between B ring and hiatal margin 2 cm- Peristalsis causes above hiatus.Schatzki ring B ringLower esophageal mucosal ring, seen as a thin, web-like annular constriction at the esophagogastric junction is associated with a small hiatal hernia.Lye stricturealkalicaustic strictures - Long, tight and smooth stricturePeptic stricture- Short and tubular narrowing.Carcinoma oesophagus- Typical annular narrowing with overhang- ing margins and destruction of the mucosa.- Rat-tail esophagus- Shouldering signLeomyomaGIST- Smooth filling defect with right angles of origin from the esophageal wall Submucosal smooth lesionCytomegalovirus esophagitis- iant ovoid flat ulcers vasculitis of submucosal vessels- Gastroesophageal junction with adjacent part of stomach is commonly affected.Herpes esophagitis- Discrete superficial punctatelinear serpentinestellatediamond shaped ulcers.Candidial esophagitis- Cobble stone mucosa- Shaggy contour of the esophagus with small diffuse superficial ulcers- Irregular plaque-like filling defectsTertiary esophageal contractions presbyesophagus, diffuse esophageal spasm, neuromuscular diseases- Corkscrew appearance- Rosary-beadShish kebab configuration- Yo-Yo motion of bariumScleroderma- Esophageal shortening- Sliding hiatus hernia- Hidebound esophagus 