Esophagus Anatomy

• The esophagus is a 25cm long muscular tube that connects the pharynx to the stomach.
• It extends from the lower border of the cricoid cartilage (C6) to the cardiac orifice of the stomach (T11).
• The esophagus passes through the posterior mediastinum and the diaphragm at the T10 level.
• It is normally collapsed and dilates only when food passes through.

C6 Vertebral Level

• At C6, the larynx transitions to the trachea, and the pharynx becomes the esophagus.
• The pharyngoesophageal sphincter and cricoid cartilage are located at this level.

Parts of the Esophagus

• Cervical Part: 4 cm long, extending from the cricoid cartilage to the manubrium sterni.
• Thoracic Part: 20 cm long, from the manubrium sterni to the esophageal opening in the diaphragm.
• Abdominal Part: 1-2 cm long, from the diaphragm to the stomach's cardiac orifice.

Relations of the Esophagus in the Neck

• Anterior: Trachea and recurrent laryngeal nerves.
• Posterior: Prevertebral muscles and vertebral column.
• Lateral: Thyroid gland, carotid sheath, and thoracic duct (on the left at C6).

Relations of the Esophagus in the Thorax

• Anterior: Trachea, recurrent laryngeal nerves, left bronchus, and left atrium.
• Posterior: Vertebral column, thoracic duct, azygos vein, right posterior intercostal arteries, and descending thoracic aorta (lower end).
• Right Side: Right mediastinal pleura and azygos vein.
• Left Side: Left mediastinal pleura, left subclavian artery, aortic arch, and thoracic duct.

Relations of the Esophagus in the Abdomen

• Anterior: Posterior surface of the left lobe of the liver.
• Posterior: Left crus of the diaphragm.
• The left and right vagus nerves lie on the anterior and posterior surfaces, respectively.

Esophageal Constrictions

• First Constriction: Pharyngoesophageal junction (C6).

• Second Constriction: Aortic arch crossing (T4).

• Third Constriction: Left principal bronchus crossing (T5-T6).

• Fourth Constriction: Diaphragm piercing (T10).

• Distances from the upper incisor teeth to the constrictions:

  • Cervical/Pharyngoesophageal: 6 inches (15 cm) at C6.
  • Thoracic: 10 inches (25 cm) at T4.
  • Diaphragmatic: 16 inches (41 cm) at T10.

• Anatomical constrictions are clinically important because:

  • Foreign bodies may get stuck there.
  • Burning sensations worsen and strictures develop after caustic fluid ingestion.
  • Common sites for esophageal carcinoma.
  • Difficult to pass esophagoscope/gastric tube.

Esophageal Sphincters

• Two sphincters present: upper and lower esophageal sphincters.
• Prevent air entry and gastric content reflux, respectively.

Upper Esophageal Sphincter

• Located at the pharynx-esophagus junction.
• Anatomical sphincter formed by the cricopharyngeus muscle (striated muscle).
• Normally constricted.

Lower Esophageal Sphincter

• Located at the gastro-esophageal junction.
• Physiological (functional) sphincter with intrinsic and extrinsic components:
  • Intrinsic: Peristalsis of esophageal muscle fibers.
  • Extrinsic: Diaphragm muscle.
• Relaxes during peristalsis to allow food into the stomach. Otherwise, it prevents gastric reflux.

Blood Supply

• Cervical Part: Inferior thyroid arteries.
• Thoracic Part: Esophageal branches of the descending thoracic aorta and bronchial arteries.
• Abdominal Part: Ascending branches of the left phrenic and left gastric arteries.

Venous Drainage

• Cervical Region: Inferior thyroid veins (systemic).
• Thoracic Region: Hemiazygos and azygos veins (systemic).
• Abdominal Region: Mainly portal vein (via left gastric vein), also systemic circulation.
• The lower esophagus drains into both systemic and portal circulation, making it a site of portocaval anastomosis.

Lymphatics

• Proximal 1/3: Deep cervical lymph nodes to the thoracic duct.
• Middle 1/3: Superior and posterior mediastinal nodes.
• Distal 1/3: Gastric and celiac lymph nodes.

Innervation

• Most of the esophagus (except the proximal part) has autonomic control via the esophageal plexus.
• Sympathetic Supply: Spinal segments T1-T10 to the sympathetic trunk.
• Parasympathetic Supply: Left and right vagus nerves to the esophageal plexus.

Clinical Notes: Esophageal Varices

• Abnormally dilated sub-mucosal veins due to portal hypertension.
• Occurs secondary to chronic liver disease like cirrhosis.
• Ruptured varices cause hematemesis (vomiting of blood).

Clinical Notes: Achalasia

• Lower esophageal sphincter fails to relax when swallowing.
• Food accumulates in the esophagus.
• Unknown cause, possibly a disorder in sphincter innervation.
• Common symptoms are dysphagia (difficulty swallowing) and regurgitation.
• Rat tail appearance in barium swallow evaluation.

Clinical Notes: Gastroesophageal Reflux Disease (GERD)

• Reflux of gastric contents into the lower esophagus.
• Acid reflux due to malfunctioning lower esophageal sphincter.
• Symptoms include acid taste, heartburn, bad breath, and chest pain.