Esophagus structure, Function, anatomy and Common Esophageal Disorders

The esophagus is a muscular tube that connects the throat (pharynx) to the stomach, allowing food and liquids to pass through during swallowing. It is part of the digestive system and is about 8 to 10 inches (20-25 cm) long in adults.

Structure of the Esophagus

Layers of the Esophageal Wall:

• Mucosa: The innermost layer, which produces mucus to help food pass smoothly.
• Submucosa: Contains glands and blood vessels.
• Muscularis: Muscle layer that contracts in waves (peristalsis) to push food downward.
• Adventitia: The outer layer, which connects the esophagus to nearby structures.

Sphincters

• Upper Esophageal Sphincter (UES): Prevents air from entering the esophagus.
• Lower Esophageal Sphincter (LES): Prevents stomach acid from flowing back into the esophagus (acid reflux/GERD).

Function of the Esophagus

• Moves food from the mouth to the stomach through peristalsis (wave-like muscle contractions).
• Prevents acid reflux with the LES.
• Protects itself from damage using mucus and constant cell renewal.

Common Esophageal Disorders

• Gastroesophageal Reflux Disease (GERD): Acid from the stomach flows back into the esophagus, causing heartburn.
• Esophagitis: Inflammation of the esophagus due to infection, acid reflux, or allergens.
• Esophageal Stricture: Narrowing of the esophagus, often due to scarring from acid reflux.
• Barrett’s Esophagus: A precancerous condition caused by long-term acid reflux.
• Esophageal Cancer: Often linked to smoking, alcohol, or chronic acid reflux.

Anatomy of the esophagus

• Esophagus: Muscular tube extending from pharynx to stomach of 25cm.
• Diameter: 2cm/length: 25cm.
• It is divided into 3 parts.

Relation

Anterior:

• Upper half: Trachea and Lt. bronchus.
• Lower half: Pericardium and Lt. atrium.
• Posterior: Vertebral column.
• Right side: Azygos vein, R.T lung and pleura.
• Left side: Arch of the aorta, L.T. lung, and pleura.

• As seen during fluoroscopy after a barium swallow the Esophagus has 3 constrictions:

• Cervical: at pharyngo-esophageal junction.
• Thoracic: arch of aorta.
• Abdominal: it passes through the esophageal hiatus of the diaphragm, 40 cm from incisors teeth.

 Layers of esophageal tube: (from outside to inside)

1. Tunica adventitia: loose connective tissue, that separates the esophagus from the surrounding structure in the mediastinum (esophagus has no serosa).
2. Tunica muscularis: smooth muscle fiber (2 layers “inner & outer”) longitudinal & circular.
3. Sphincter: upper: anatomical sphincter, Lower: high-pressure zone (physiologic).
4. Submucosa: connective tissue contains: Small blood vessels, Lymphatic, nerves, and mucous glands.
5. Tunic Mucous: Non-keratinized stratified squamous epithelium. Z-line (important landmark): The demarcated line shows the transition between esophageal mucosa (pale) and gastric cardinal mucosa (red in color).

So, it identifies the esophageal gastric junction any proximal extension of gastric or intestinal epithelium is considered pathological and could be attributed to gastroesophageal reflux disease.

Peritoneal covering of esophagus:

The posterior surface of the abdominal part of the esophagus is covered by a protonium of omental bursa (lesser curvature) continuous with a covering of the posterior surface of the stomach.

The vagal trunk:

Associated with the esophagus entering the abdominal cavity (anterior, posterior)

• Anterior vagal trunk: Formed of several small trunks whose fiber come from the left vagus. Rotation of the gut during development brings it on the anterior surface.
• Posterior vagal trunk: Single trunk the fiber comes from the right, vagus, Rotation brings it on the posterior surface, Not truly attached to the esophagus.

Anatomy of diaphragm:

The diaphragm has 3 major openings:

• Esophageal hiatus T10.
• Caval hiatus for IVC: (T8).
• Aortic hiatus. T12.

The inferior vena cava: runs posterior to the liver and through the diaphragm at the right side of the central tendon it can be very close to the margin of Rt crus.

1. So, during para esophageal hernia repair or gastroesophageal reflex repair surgery (at which the esophageal hiatus is large with narrow) we must take care that IVC is not injured.
2. The diaphragmatic legs: Extended from the esophagus to the vertebral column. These legs split at the central tendon and extend around the esophagus to create hiatus. The inferior area between 2 legs is known as crural decassation or medial arcuate ligament.

Structure passing through esophageal hiatus:

1. Esophagus.
2. Pharenoesopheal ligament.
3. Lt, Rt vagus nerves.
4. Esophageal branches of the left gastric artery and vein.
5. Lymphatics.

Pharyngoesophageal ligament:

Extension of the inferior diaphragmatic fascia and attached to the esophagus at the gastroesophageal junction:

• Keeps this area of high pressure at its site.
• Prevents its migration to the chest.
• seals the abdominal cavity from the thoracic cavity.

The ligament has 2 layers:

• Upper: extended to the mediastinum and attached the esophagus to the superior aspect of the diaphragmatic hiatus.
• Lower: secure the bottom of GEJ and proximal stomach to the inferior surface of the diaphragm to prevent herniation of the stomach.

The ligament is not completely attached to the esophagus. there is some fat between them and this permits free mechanical movement of this area (diaphragm -esophagus) during respiration and swallowing.

The gastroesophageal junction:

• Below the esophageal hiatus of the diaphragm in the abdomen.
• The longitudinal and circular muscle fibers cross the GEJ where they acquire an additional oblique muscle layer (sliding fiber) which is firm (angle of HIS) → has a role as a barrier for reflux.
• The lower esophageal sphincter is made of circular muscle.

Factor involved in normal prevention of reflux:

1- Anatomical:

• Lower esophageal sphincter (pressure, total length, intra-abdominal length)
• The angle of His (flap valve mechanism).
• Mucosal rosette at GEJ (mucosal fold).

2- Esophageal clearance:

• Salvia (lubricate, neutralize).
• Antegrade peristalsis.

3- Gastric emptying: prevent increasing pressure in the stomach by removing food.

• The pressure of the esophageal sphincter drops only when: Swallowing to permit passage of food, Vomiting, Blech → when the fundus is filled with gas.
• The total length of the oesophagus decreases, and pressure as the stomach extends shortening of LES, and increases the pressure of LES. This is called the balloon effect.
• Citra abdominal length of the Esophagus
• Increasing the length helps to prevent reflexes.
• If it is short the pressure of the high-pressure zone can be overcome by a small increase in the abdominal pressure which leads to reflux.

Investigations

• Empiric treatment
• Radiograph
• Endoscopy
• Impedance
• Esophageal body and gastric function manometry
• 24-hour amputator PH monitoring.

Common pathology at the hiatus

1. Gastroesophageal reflux: the condition which develops when the reflux of stomach content causes complication. It occurs when >=2 heartburn/ weak. Adversely affects individuals well being. There is weak evidence that lifestyle aggravates GRED:

• Obesity.
• Smoking.
• Physical activity.
• Overeating.

2- Achalasia of the cardia: Failure of relaxation of lower esophageal sphincter. Its primary esophageal disorder is characterized by the absence of peristalsis and impaired relaxation of the lower esophageal sphincter in response to swallowing. This abnormality obstructs the gastroesophageal junction Manometry shows (no peristalsis, increase LES pressure).

Treatment of achalasia

Laparoscopic: Heller myotomy. cut 1.5 cm on the gastric muscle and this leads to decreased pressure.

Vagotomies: surgical cutting of the vagal nerve to reduce the acid secretion from the stomach → used in the treatment of peptic ulcer. It’s performed when acid production in the stomach can’t be reduced by other means.

The vagotomy procedure decreased in the last 20 years. It has become clear that gastric ulcers are caused by Pylori, not acid secretion. The drug became more effective in treating ulcers. Vagotomy is performed in conjugation with other procedures. As: removal of the stomach (antrectomy – gastrectomy) and drainage procedure (pyloroplasty).

There are 3 steps of vagotomy:

1. Truncal or total abdominal vagotomy: The main vagal trunk is divided + drainage procedure (pyloroplasty → patient suffers from (diarrhea).
2. Selective vagotomy (total gastric): vagal trunk dissected close to a hepatic branch, colic, Rarely used.
3. Highly selective: The small branch to the stomach is cut to reduce stimulation of acid production but the branch to the pylorus is maintained to keep the relaxation.

You can subscribe to Science Online on YouTube from this link: Science Online  

You can download Science online application on Google Play from this link: Science online Apps on Google Play

Esophagus diseases, Dysphagia causes, Achalasia and Symptomatic Diffuse Esophageal spasm

Pharynx function, anatomy, location, muscles, structure, and Esophagus parts

Tongue function, anatomy and structure, Types of lingual papillae and Types of cells in taste bud

Mouth Cavity divisions, anatomy, function, muscles, Contents of Soft palate and Hard palate

Temporal and infratemporal fossae contents, Muscles of mastication and Otic ganglion