Applied anatomy and physiology of Esophagus .pptx
- 2. Anatomy
- 4. Relations… • Right side- mediastinal pleura & terminal part of azygous vein • Left side- left subclavian artery, aortic arch, thoracic duct, mediastinal pleura • When esophagus pierces the diaphragm, it is accompanied by two vagi, branches of left gastric artery & lymphatic vessels. • In abdomen – left lobe of liver anteriorly & left crus of diaphragm posteriorly.
- 5. Constrictions I – Pharyngo-esophageal junction -15cm from incisor teeth. II- Aortic arch and left bronchus crosses esophagus anteriorly- 25cm from incisor teeth. III- Esophagal hiatus 40cm from incisor
- 6. Clinical importance of constrictions of esophagus • Common site for lodgment of foreign body • Common site for stricture formation after corrosive ingestion • Common site for carcinoma of esophagus • Difficult sites for passage of esophagoscope.
- 7. Length of the Esophagus • The distance between the cricoid cartilage and the gastric orifice. • In adults, it ranges from 22 to 28 cm, 3 to 6 cm of which is located in the abdomen. • length of the esophagus is related to the subject's height rather than sex. • Cervical – 5cm • Thoracic -18-20cm • Abdomen – 2-4cm
- 8. Blood supply • Upper 1/3 – inferior thyroid artery • Middle 1/3 – direct branches from aorta. • Lower 1/3 – left gastric artery
- 9. Venous drainage • Upper 1/3 – inferior thyroid vein • Middle 1/3 – Azygous and hemi- azygous vein. • Lower 1/3- left gastric vein
- 10. Nerve supply (Extrinsic) • Esophageal plexus – formed by vagus nerves by joining with sympathetic nerves below the root of lungs. • LARP- left vagus anteriorly • Right vagus posteriorly
- 11. Nerve supply • Extrinsic –vagus • Intrinsic – • Auerbach /myentric plexus - between longitudinal and circular muscle • Peristalsis • Meissner’s plexus - at submucosal level – for secretion • Meissner’s submucosal plexus is sparse in the esophagus. • The parasympathetic nerve supply is mediated by branches of the vagus nerve • that has synaptic connections to the myenteric (Auerbach’s) plexus.
- 12. Lymphatic drainage • Upper 1/3- • deep cervical nodes. • Middle 1/3- • superior & posterior mediastinal nodes • Lower 1/3- • celiac nodes
- 13. Diameter of the Esophagus • The esophagus is the narrowest tube in the intestinal tract. • At rest, the esophagus is collapsed; it forms a soft muscular tube . • Flat in its upper and middle parts, with a diameter of 1.6 cm. • The lower esophagus is rounded, and its diameter is 2.4 cm.
- 14. Musculature • The musculature of the upper esophagus & UES is striated. • This is followed by a transitional zone of both striated and smooth muscle. • Proportion of the smooth muscle is progressively increasing. • In the lower half of the esophagus, there is only smooth muscle. • It is lined throughout with squamous epithelium.
- 15. Layers 1. Mucosa – • epithelium • Basement membrane • Lamina Propria 2. Submucosa- strongest layer 3. Muscular propria- • Inner circular • Outer longitudinal 4. Adventitia –visceral peritoneum
- 16. Periesophageal Tissue, Compartments, and Fascial Planes • Unlike the general structure of the digestive tract, the esophageal tube has neither mesentery nor serosal coating. • Its position is within the mediastinum and a complete envelope of loose connective tissue allow the esophagus extensive transverse and longitudinal mobility. • The esophagus may be subjected to easy blunt stripping from the mediastinum.
- 17. Clinical relevance • The connective tissues in which the esophagus and trachea are embedded are bounded by fascial planes, • the pre tracheal fascia anteriorly and • the prevertebral fascia posteriorly. • In the upper part of the chest, both fascia unite to form the carotid sheath.
- 18. Tunica Adventitia • This thin coat of loose connective tissue envelops the esophagus. • connects it to adjacent structures. • contains small vessels, lymphatic channels, and nerves.
- 19. Tunica Muscularis • The tunica muscularis coats the lumen of the esophagus in two layers : • the external muscle layer parallels the longitudinal axis of the tube, • the muscle fibers of the inner layer are arranged in the horizontal axis. • For this reason, these muscle layers are classically called longitudinal and circular, respectively.
- 20. Submucosa • The submucosa is the connective tissue layer that lies between the muscular coat and the mucosa. • It contains a meshwork of small blood and lymph vessels, nerves, and mucous glands. • The duct of deep esophageal glands pierce the muscularis mucosae.
- 21. Tunica Mucosa • The mucous layer is composed of three components: • the muscularis mucosae, • the tunica / lamina propria, and • the inner lining of nonkeratinizing stratified squamous epithelium .
- 22. Physiology of the Esophagus and Its Sphincters
- 23. Physiology • The musculature of the esophagus = predominantly striated at the level of the UES and proximal 1 to 2 cm of the esophagus. • mixed striated = smooth muscle transition zone spanning 4 to 5 cm • Entirely smooth muscle structure = in the distal 50% to 60% of the esophagus, including the LES
- 24. SWALLOWING PROCESS • Normal human subjects swallow on average 500 times a day. • The act of swallowing can be divided into three stages: 1. the oral (voluntary) stage, 2. the pharyngeal (involuntary) stage, and 3. the esophageal stage. • These stages are a continuous process closely coordinated through the medullary swallowing centers.
- 25. Esophageal Stage • The esophageal stage of swallowing starts once the food is transferred from the oral cavity through the UES into the esophagus. • This active process is achieved by contractions of the circular and longitudinal muscles of the tubular esophagus and coordinated relaxation of the LES. • Esophageal peristalsis is controlled by afferent and efferent connections of the medullary swallowing center via the vagus nerve (cranial nerve X).
- 26. • The vagus nerve carries both stimulating (cholinergic) and inhibitory (noncholinergic, nonadrenergic) information to the esophageal musculature. • In addition to the central nervous system control, the myenteric (Auerbach) plexus • plays a major role in coordinating peristalsis in the smooth muscle portion of the distal esophagus.
- 27. Esophageal peristalsis • Esophageal peristalsis is the result of sequential contraction of the circular esophageal muscle. • Three distinct patters of esophageal contractions have been described: 1. Primary peristalsis 2. Secondary peristalsis 3. Tertiary contractions.
- 28. Primary peristalsis • Primary peristaltic contractions are the usual form of the contraction waves of circular muscles that progress down the esophagus; • they are initiated by the central mechanisms that follow the voluntary act of swallowing. • During primary peristalsis, the LES is relaxed, starting at the initiation of swallowing and lasting until the peristalsis reaches the LES.
- 29. Secondary peristalsis • Secondary peristaltic contractions are the contraction waves of the circular esophageal muscle occurring in response to esophageal distention. • They are not a result of central mechanisms. • The role of secondary peristaltic contractions is to clear the esophageal lumen of ingested material not cleared by primary peristalsis or material that is refluxed from the stomach. • Tertiary contractions are primarily identified during barium x-ray studies and represent non-peristaltic contraction waves that leave segmental indentations on the barium column.
- 30. LES • Normal LES resting pressure ranges from 10 to 45 mm Hg above the gastric baseline level. • The function of the LES is to • prevent gastroesophageal reflux and • to relax with swallowing to allow movement of ingested food into the stomach.
- 31. Perforation of the oesophagus • Causes - 1. usually iatrogenic (at therapeutic endoscopy) or 2. due to ‘barotrauma’ (spontaneous perforation). 3. Pathological perforation- rare 4. Penetrating injury
- 32. Barotrauma (spontaneous perforation, Boerhaave syndrome) • This occurs classically when a person vomits against a closed glottis. • The pressure in the oesophagus increases rapidly, and the oesophagus bursts at its weakest point in the lower third, sending a stream of material into the mediastinum and often the pleural cavity as well. • The condition was first reported by Boerhaave , who reported the case of a grand admiral of the Dutch fleet who was a glutton and practised auto emesis.
- 33. Boerhaave syndrome… • Most serious type of perforation • because of the large volume of material that is released under pressure. • mediastinitis • Barotrauma has also been described in relation to other pressure events when the patient strains against a closed glottis (e.g. defaecation, labour, weight-lifting).
- 34. Diagnosis of spontaneous perforation • history • severe pain in the chest or upper abdomen following a meal or a bout of drinking. • shortness of breath • O/E- • rigidity on examination of the upper abdomen, even in the absence of any peritoneal contamination. • D/D • myocardial infarction, • perforated peptic ulcer or • pancreatitis if the pain is confined to the upper abdomen.
- 35. Boerhaave syndrome… 1. Chest x-ray - confirmatory • air in the mediastinum, pleura or peritoneum. 2. A contrast swallow or 3. CT scan
- 36. Pathological perforation • Free perforation of ulcers or tumors of the oesophagus into the pleural space is rare. • Erosion into an adjacent structure with fistula formation is more common. • Aerodigestive fistula is most common and usually encountered in primary malignant disease of the oesophagus or bronchus. • Covering the communication with a self-expanding metal stent is the usual solution.
- 37. Penetrating injury • Perforation by knives and bullets is uncommon
- 38. Instrumental perforation • Instrumentation is by far the most common cause of perforation. • Incidence - 1:4000 examinations /UGIE
- 39. Diagnosis of instrumental perforation • History and physical signs may be useful pointers to the site of perforation. 1. Cervical perforation: • pain localised to the neck, • hoarseness, • painful neck movements and • subcutaneous emphysema.
- 40. 2. Intrathoracic and intra-abdominal perforations, (more common), • Immediate symptoms and signs • chest pain, • haemodynamic instability, • oxygen desaturation . • evidence of subcutaneous emphysema, pneumothorax or hydropneumothorax.
- 41. Treatment of oesophageal perforations • Perforation of the oesophagus usually leads to mediastinitis. • The loose areolar tissues of the posterior mediastinum allow a rapid spread of gastrointestinal contents. • Aim of treatment • limit mediastinal contamination and • prevent or deal with infection.
- 42. Decision between operative and non- operative management rests on four factors 1. the site of the perforation (cervical versus thoraco-abdominal oesophagus); 2. the event causing the perforation (spontaneous versus instrumental); 3. underlying pathology (benign or malignant); 4. the status of the oesophagus before the perforation (fasted and empty versus obstructed with a stagnant residue).
- 43. Non-operative treatment of Instrumental perforations • Cervical oesophagus - are usually small perforation and can nearly always be managed conservatively. • The development of a local abscess is an indication for cervical drainage preventing the extension of sepsis into the mediastinum.
- 44. Indication for non-operative management (thoraco-abdominal perforation) • when the perforation is detected early and prior to oral alimentation. • absence of • crepitus, • diffuse mediastinal gas, • Hydro-pneumothorax or pneumo-peritoneum; • mediastinal containment of the perforation with no evidence of widespread extravasation of contrast material; • no evidence of ongoing luminal obstruction or a retained foreign body. • patients who have remained clinically stable despite diagnostic delay.
- 45. Principles of non-interventional management • nasogastric suction and • broad-spectrum intravenous antibiotics
- 46. Indication of Surgical management • unstable with sepsis or shock; • have evidence of a heavily contaminated mediastinum, pleural space or peritoneum; • have widespread intra-pleural or intra-peritoneal extravasation of contrast material.
- 47. Surgery • direct repair, • the deliberate creation of an external fistula or, • rarely, oesophageal resection with a view to delayed reconstruction. • Direct repair • if the perforation is recognised early (within the first 4–6 hours) and the extent of mediastinal and pleural contamination is small. • After 12 hours, the tissues become swollen and friable , primary repair not possible.
- 48. MALLORY–WEISS SYNDROME • Forceful vomiting may produce a mucosal tear at the cardia rather than a full perforation. • In Boerhaave’s syndrome, vomiting occurs against a closed glottis, and pressure builds up in the oesophagus. • In Mallory– Weiss syndrome, vigorous vomiting produces a vertical split in the gastric mucosa, immediately below the squamo-columnar junction at the cardia in 90 per cent of cases. • In only 10 per cent is the tear in the oesophagus.
- 49. MALLORY–WEISS SYNDROME… • Clinical feature • Haematemesis • Surgery is rarely required.