Esophagus 2 Physiology swallowing

The esophagus is a muscular tube fixed at its upper end to the cricoid cartilage and at its lower end to the diaphragm. This provides it transverse and longitudinal mobility, this mobility allows peristaltic wave to carry the bolus and this mobility also allows of intra thoracic organs to displace the esophogus without altering its food carrying functions.

The tube is lined by sqaumous epithilum with no keratin layer the submucosa contains elastic and fiberous tissue this forms the lamina propria the strongest and dependable layer for stitching in all surgery of esophagus. The lymph flow is not segmental and the submucouslymph plexus allows the lymph to flow long distance up and down, thus upper end cancers may show involvement of superior gastric glands and lower end carcinomas may show mediaitinal glands

1.1 PHYSIOLOGY 

The upper end of the oesophagus acts as a sphincter (UES) and  is

about 3 cm. in length and has a intraluminal resting pressure  of

20-60 mm of Hg.

 - With the act of swallowing this sphincter relaxes for 0.5 to 1

   second  as  the  bolus enters  the  oesophagus  the  sphincter

   contracts  and peristaltic waves of the oesophagus propel  the

   bolus to the lower sphincter (LES)

 - This (LES)  is the last 3 to 5 cm of the oesophagus that  acts

   as  a  sphincter though there is  no  demonstrable  anatomical

   structure like a sphincter.

 - This zone of the oesophagus develops a pressure of 10-20 mm of

   Hg  and  prevents regurgitation of stomach contents  into  the

   oesophagus.

Swallowing physiology

At the end of mastication the semisolid bolus is pushed by the postenor part of the tongue into the posterior oropharynx.

The soft palate (SP) rises to close of the opening of the neso pharynx. The hyoid and larynx move upward and the epiglottis classes of the larynx. These tow (SP+E) close of the nasal air passage and the larynx. The bolus is helped on its way towards the upper opening of the esophagus by the elevation of larynx.

The UES relaxes and the contractions of pharyngeal constrictors push the bolus into the esophagus. During the swallowing the breath is held. Further progress of the bolus is through the peristalsis of the esophagus.

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