Constrictions of esophagus are present at all sites except:

Ans. C. Where it is surrounded by right crus of diaphragmThe esophagus has four points of constriction. When a corrosive substance, or a solid object is swallowed, it is most likely to lodge and damage one of these four points. These constrictions arise from particular structures that compress the esophagus. These constrictions are:a. At the start of the esophagus, where the laryngopharynx joins the esophagus, behind the cricoid cartilageb. Where it is crossed on the front by the aortic arch in the superior mediastinumc. Where the esophagus is compressed by the left main bronchus in the posterior mediastinumd. The esophageal hiatus where it passes through the diaphragm in the posterior mediastinum