Anatomy and physiology of esophagus

anatomy, physiology, and function of esophagus. oesophagus . structure of esophagus .

1. Anatomy and Physiology of Oesophagus Dr H imanshu Mishra PG Resident Department of ENT

2. APPLIED ANATOMY 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 (T11 ) It shows three normal constrictions 1. At pharyngo-oesophageal junction (C6)— 15 cm from the upper incisors. 2. At crossing of arch of aorta and left main bronchus (T4 )— 25 cm from upper incisors. 3. Where it pierces the diaphragm (T10)— 40 cm from upper incisors.

3. These areas are where most oesophageal foreign bodies become entrapped. The most common site of oesophageal impaction is at the thoracic inlet About 70% of blunt foreign bodies that lodge in the oesophagus do so at this location Another 15% become lodged at the mid oesophagus , in the region where the aortic arch and carina overlap the oesophagus on chest radiograph. The remaining 15% become lodged at the lower oesophageal sphincter (LES) at the gastroesophageal junction.

4. The wall of oesophagus consists of four layers . (a) Mucosa , which is lined by stratified squamous epithelium . (b ) Submucosa , which connects mucosa to muscular layer. (c) Muscular layer , which has inner circular and outer longitudinal fibres . ( d) Fibrous layer , which forms loose covering of oesophagus

5. NERVE SUPPLY Parasympathetic fibres come from vagus nerves (X) sympathetic fibres from the sympathetic trunk

6. LYMPHATIC DRAINAGE The cervical, thoracic and abdominal parts drain respectively into deep cervical, posterior mediastinal and gastric Nodes.

7. APPLIED PHYSIOLOGY Manometric studies have shown two high pressure zones in oesophagus and they form the physiological sphincters . The upper oesophageal sphincter starts at the upper border of oesophagus and is about 3–5 cm in length and functions during the act of swallowing. The lower oesophageal sphincter is situated at lower portion of oesophagus. It is also 3–5 cm in length and functions to prevent oesophageal reflux.

8. PHYSIOLOGY OF SWALLOWING The act of swallowing is divided into three phases: Oral or buccal phase . The food which is placed in the mouth is chewed, lubricated with saliva, converted into a bolus and then propelled into the pharynx by elevation of the tongue against the palate.

9. Pharyngeal phase. It is initiated when the bolus of food comes into contact with pharyngeal mucosa . Oesophageal phase. After food enters the oesophagus, the cricopharyngeal sphincter closes and the peristaltic movements of oesophagus take the bolus down the stomach.

10. Regurgitation of food back from stomach into oesophagus is prevented by : ( i ) tone of gastro-oesophageal sphincter, (ii) negative intrathoracic pressure, (iii) pinch-cock effect of diaphragm, (iv) mucosal folds, (v) oesophagogastric angle and (vi) slightly positive intra-abdominal pressure.

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