<prompt> Constriction of esophagus are all EXCEPT:Arch of aortaLeft main bronchusLeft atriumDiaphragm  <response>: ANSWER; C Left atriumREF: P L Dhingra, edition, page 64, Keith L. Moore, 4th edition, page 109APPLIED ANATOMY OF OESOPHAGUS:It is a fibro muscular tube, about 25 cm long in an adult. It extends from the lower end of pharynx C6 to the cardiac end of stomach T1l. It runs vertically but inclines to the left from its origin to thoracic inlet and again from T7 to oesophageal opening in the diaphragm. It shows three normal constrictions and it is important to know their location at oesophagoscopy. They are:1 At pharyngo-oesophageal junction C6 - 15 cm from the upper incisors.2. At crossing of arch of aorta and left main bronchus T 4 - 25 cm from upper incisors.3. Where it pierces the diaphragm T 10 - 40 cm from upper incisors. Foreign bodies in the oesophagus can be held up at these constrictions Check star in the following diagram 