ANSWER: (B) 15 on, 25 cm, 40 cmREF: P L Dhingra, 4th edition, page 64, Keith L. Moore 4th edition page 109Repeat from June 2010APPLIED 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 (Til). It runs Tertically 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:At pharyngo-oesophageal junction (C6) - 15 cm from the upper incisors.At crossing of arch of aorta and left main bronchus (T 4) - 25 cm from upper incisors.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