Esophagus - الأهلية

Anatomy of Esophagus

• Muscular tube that is 24-33 cm (25cm) in length
• Diameter measures 1/2 inch
• Begins at the cricopharyngeal sphincter, opposite the 6th cervical vertebra
• Ends at the cardia, at the level of the 11th thoracic vertebra

Parts and Course

• Cervical part: 3-5 cm long, extending from the 6th cervical vertebra (opposite the cricoid cartilage) to the 1st thoracic vertebra (at the sternoclavicular joint level).
• Thoracic part: 18-22 cm long, from the 1st to the 10th thoracic vertebra, passing through the superior and posterior mediastinum, piercing the diaphragm at the 10th thoracic vertebra level.
• Abdominal part: 3-6 cm long, from the 10th to the 11th thoracic vertebra, passing through the left crus of the diaphragm.

Relations

• In the neck:
  • Anterior: Trachea, both recurrent laryngeal nerves (RLN)
  • Posterior: Vertebral column
  • Left: Left lobe of the thyroid gland
  • Right: Right lobe of the thyroid gland
• Superior mediastinum:
  • Anterior: Trachea, left RLN
  • Posterior: Vertebral column with its anterior ligament
  • Left: Left lung & pleura, aortic arch, left subclavian artery, thoracic duct
  • Right: Right lung & pleura, azygos vein
• Posterior mediastinum:
  • Anterior: Left bronchus, right pulmonary artery, left atrium, left vagus nerve, diaphragm
  • Posterior: Vertebral column, azygos vein, thoracic duct, descending aorta, right vagus nerve
  • Left: Descending aorta (above), left lung & pleura (below)
  • Right: Right lung & pleura, azygos vein, thoracic duct
• In the abdomen:
  • Anterior: Left lobe of the liver, anterior vagal trunk
  • Posterior: Right crus of the diaphragm, posterior vagal trunk
  • Left: Fundus of the stomach
  • Right: Caudate lobe of the liver

Microscopic Anatomy

• Esophageal wall layers (from inside to outside):
  • Mucosa: Stratified squamous epithelium, similar to gastric mucosa at the cardia (without peptic or oxyntic cells)
  • Submucosal: Loose connective tissue with neural plexus of Meissner
  • Musculosa: Striated muscle in the upper 1/3, and smooth muscle fibers (inner circular, outer longitudinal layers) in the lower 2/3; Auerbach's plexus between muscle layers
  • Adventitia: Lacks serosal lining, except in the abdominal part

Blood Supply

• Cervical part: Branches of the inferior thyroid artery
• Thoracic part: Branches of the descending thoracic aorta and bronchial arteries
• Abdominal part: Left gastric artery, inferior phrenic artery, and Belsey's artery (constant artery between inferior phrenic and left gastric arteries)

Venous Drainage

• Cervical part: Into brachiocephalic veins
• Thoracic part: Into azygos and hemiazygos veins (systemic)
• Abdominal part: Into left and short gastric veins (portal)

Lymphatic Drainage

• Cervical part: Deep cervical lymph nodes
• Thoracic part: Paratracheal & tracheobronchial lymph nodes
• Abdominal part: Left gastric lymph nodes, then into coeliac lymph nodes

Nerve Supply

• Cervical part:
  • Parasympathetic: From recurrent laryngeal nerve (vagal)
  • Sympathetic: Around the inferior thyroid artery
• Thoracic part:
  • Parasympathetic: Esophageal plexus of vagus (Rt & LT), controls peristaltic waves
  • Sympathetic: From the greater splanchnic nerve
• Abdominal part:
  • Parasympathetic: From anterior and posterior gastric nerves (vagal)
  • Sympathetic: Around the coeliac plexus

Applied Anatomy

Sphincters

• Upper Esophageal Sphincter:
  • Formed by the cricopharyngeus muscle (anatomical sphincter)
  • About 4 cm long
  • Closed at rest (continuous contraction state) to prevent air entry, opens during swallowing
• Lower Esophageal Sphincter (cardiac sphincter):
  • Functional sphincter, normally prevents reflux from the stomach
  • Anti-reflux mechanisms:
    • Lower 2 cm of the esophagus is intra-abdominal (squeezed by intra-abdominal pressure)
    • Circular muscle fibers around the lower esophageal end
    • Valvular effects of the esophago-gastric angle (angle of His)
    • Rosette-like arrangement of the cardiac gastric mucosa
    • Pinch-cock action of right crus of diaphragm

Constrictions of the Esophagus

• Locations (from incisor teeth):
  • Cricopharyngeal constriction: 6 inches (beginning)
  • Aortic constriction: 9 inches (crossed by the aortic arch)
  • Pulmonary constriction: 12 inches (crossed by left main bronchus)
  • Diaphragmatic constriction: 15 inches (esophageal hiatus)
  • Cardiac constriction: 17 inches (end)
• These constrictions are sites of foreign body arrest, areas exposed to mechanical/chemical trauma, and common sites of malignancy.

Surgical Division

• Surgical division into 3 parts:
  • Upper 1/3: From the beginning to the aortic arch (curves to the left)
  • Middle 1/3: From the aortic arch to the inferior pulmonary vein (curves to the right)
  • Lower 1/3: From the inferior pulmonary vein to the cardiac end (curves to the left)

Surgical Importance

• Lower end is a key site for porto-systemic anastomosis.
• Left gastric veins (portal) anastomose with tributaries of the azygos and hemiazygos veins (systemic). Esophageal varices form due to anastomotic vein dilation in portal hypertension.

Lymphatic Course

• Lymphatics run longitudinally within the submucosa and drain into regional lymph nodes, leading to submucosal tumor extension in esophageal carcinoma.

Surgical Challenges

• High risk of leakage in esophageal surgical anastomosis due to:
  • Thin and weak muscular layer (poor suture holding)
  • Lack of serous covering (except abdominal part)
  • Poor blood supply

Congenital Anomalies

Atresia with or without Tracheo-Esophageal Fistula (TOF)

• Failure of complete canalization of an esophageal segment (with/without TOF), related to genetic/chromosomal anomalies (trisomy 13 & 18).
• Types:
  • Type I: 85%, lower esophageal segment opens into the trachea, upper segment ends blindly
  • Type II: 2%, upper segment opens into the trachea, distal segment ends blindly
  • Type III: 1%, both segments open into the trachea
  • Type IV: 8%, both segments end blindly, mid-esophagus absent (atresia without fistula)
  • Type V: 4%, TOF with intact esophagus (fistula without atresia, H-shaped)

Clinical Picture

• Males more often affected. Newborns regurgitate all feeds with choking, coughing, and cyanosis during feeding. Excessive mucus, inability to swallow, aspiration pneumonia, dehydration, hypoglycemia, and hypokalaemia result from feeding failure, manifesting at birth.

Associated Congenital Anomalies (VACTERL)

• Vertebral: Fused or hemivertebrae
• Anorectal: Imperforate anus
• Cardiac: VSD
• Tracheal: TOF and tracheomalacia
• Esophageal: Atresia
• Renal: Single kidney or VUR
• Limb Anomalies: Absent thumb, radial dysplasia

Investigations

• Clinical: Failure to pass 10F nasogastric tube into the stomach.
• Radiological:
  • X-ray (erect position): Presence of gas (fistula to lower pouch) or absence of gas (blind lower pouch)
  • Barium swallow: Via catheter with Lipidol
• Other: Tracheoscopy (site/number of TOF, tracheal structure/tracheomalacia), baby gram (confirm associated anomalies)

Treatment

• Keep infant flat and in lateral position to prevent secretion accumulation. Clear secretions from the upper esophageal pouch with suction.
• Surgical intervention:
  • Aim: Restore esophageal continuity
  • Technique (if fistula is present):
    • Esophagus is cut from the trachea (which is closed)
    • If there's no gap between segments, anastomosis around a catheter is performed.
    • If segments are too far apart, do colon bypass at one year of age.

Dysphagia Lusoria (Vascular Compression)

• Esophageal compression due to congenital abnormal vessels (e.g., double aortic arch encircling the esophagus, or a right subclavian artery from the descending aorta causing tracheal/esophageal obstruction).

Clinical Picture

• Asymptomatic until 45-50 years. Dysphagia, dyspnea, and stridor result from atherosclerosis-induced rigid arterial wall compressing the esophagus and trachea.

Investigations

• Barium swallow: Posterior indentation of the esophagus.

Treatment

• If symptoms are severe, the abnormal vessel is divided or transposed.