أسئلة المحاضرة التاسعة أهلية Esophagus Anatomy & Congenital Anomalies

• Study notes for lecture 9, focusing on the esophagus

Anatomy of the Esophagus

• The esophagus is a muscular tube, approximately 24-33 cm (25 cm) long, and 1/2 inch in diameter.
• It begins at the cricopharyngeal sphincter, opposite the 6th cervical vertebra.
• It terminates at the cardia, at the level of the 11th thoracic vertebra.

Parts and Course

• The esophagus is divided into cervical, thoracic, and abdominal parts.

Cervical Part

• Length: 3-5 cm long
• From: 6th cervical vertebra (opposite the cricoid cartilage)
• To: 1st thoracic vertebra (at the level of the sternoclavicular joint)

Thoracic Part

• Length: 18-22 cm long
• From: 1st thoracic vertebra
• To: 10th thoracic vertebra, passing through the superior mediastinum, then the posterior mediastinum, where it pierces the diaphragm at the level of the 10th thoracic vertebra.

Abdominal Part

• Length: 3-6 cm long
• From: 10th thoracic vertebra
• To: 11th thoracic vertebra, passing through the left crus of the diaphragm.

Relations of the Esophagus

In The Neck

• Anteriorly: Trachea and both recurrent laryngeal nerves (RLN)
• Posteriorly: Vertebral column
• Left side: Left lobe of the thyroid gland
• Right side: Right lobe of the thyroid gland.

Superior Mediastinum

• Anteriorly: Trachea and left recurrent laryngeal nerve (RLN)
• Posteriorly: Vertebral column with its anterior ligament
• Left side: Left lung & pleura, aortic arch, left subclavian artery, and thoracic duct
• Right side: Right lung & pleura, azygus vein.

Posterior Mediastinum

• Anteriorly: Left bronchus, right pulmonary artery, left atrium, left vagus nerve, and diaphragm
• Posteriorly: Vertebral column, azygos vein, thoracic duct, descending aorta, and right vagus nerve
• Left side: Descending aorta (above), left lung & pleura (below)
• Right side: Right lung & pleura, azygus vein, thoracic duct

In The Abdomen

• Anteriorly: Left lobe of the liver, anterior vagal trunk.
• Posteriorly: Right crus of the diaphragm and posterior vagal trunk
• Left side: Fundus of stomach
• Right side: Caudate lobe of the liver

Microscopic Anatomy

• The esophageal wall consists of layers from within outwards.
• Mucosa: Stratified squamous epithelium, which transitions to gastric mucosa without peptic or oxyntic cells at the cardia.
• Submucosal: Loose connective tissue containing the neural plexus of Meissner.
• Musculosa: Striated muscle in the upper 1/3, smooth muscle fibers in the lower 2/3 arranged as inner circular and outer longitudinal layers; Auerbach's plexus is found between the 2 muscle layers.
• Adventia: Lacks a serosal lining, except for the abdominal part.

Blood Supply

Arterial Supply

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

Venous Drainage

• Cervical part: Drains into brachiocephalic veins.
• Thoracic part: Drains into azygus and hemiazygus veins (systemic).
• Abdominal part: Drains into left and short gastric veins (portal).

Lymphatic Drainage

• Cervical part drains into deep cervical lymph nodes.
• Thoracic part drains into para-tracheal and tracheobronchial lymph nodes.
• Abdominal part drains into left gastric lymph nodes, then into coeliac lymph nodes.

Nerve Supply

Parasympathetic

• Cervical part: From recurrent laryngeal nerve (vagal).
• Thoracic part: From esophageal plexus of vagus (right and left), controlling peristaltic waves.
• Abdominal part: From anterior and posterior gastric nerves (vagal).

Sympathetic

• Cervical part: Around the inferior thyroid artery.
• Thoracic part: From greater splanchnic nerve.
• Abdominal part: Around the coeliac plexus.

Applied Anatomy

Sphincters

• Upper Esophageal Sphincter
  • Formed of the cricopharyngeus muscle.
  • It is an anatomical sphincter, approximately 4 cm long.
  • Closed at rest, preventing air entry and opening during swallowing.
• Lower Esophageal Sphincter (Cardiac Sphincter)
  • It is a functional sphincter that normally prevents reflux from the stomach.
  • The anti-reflux mechanism includes:
    • Lower 2 cm of the esophagus being intra-abdominal, squeezed by intra-abdominal pressure.
    • Circular muscle fibers around the lower end of the esophagus.
    • Valvular effects of the esophago-gastric angle (angle of His).
    • Rosette-like arrangement of the cardiac gastric mucosa.
    • Pinch-cock action of the right crus of the diaphragm.

Constrictions of the Esophagus

• (6-9-12-15-18 inches from the incisor teeth)
• Cricopharyngeal constriction: At its beginning (6 inches).
• Aortic constriction: Where it is crossed by the aortic arch (9 inches).
• Pulmonary constriction: Where it is crossed by the left main bronchus (12 inches).
• Diaphragmatic constriction: At the esophageal hiatus (15 inches).
• Cardiac constriction: At its end (17 inches).
• These sites are where swallowed foreign bodies arrest, are most exposed to mechanical/chemical trauma, and are common sites of malignancy.

Surgical Division

• The esophagus is surgically divided into 3 parts:
  • Upper 1/3: From its 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).

Lower End Significance

• One of the most important sites of porto-systemic anastomosis.
  • Anastomosis occurs where the left gastric veins (portal) connect with tributaries of the azygus and hemiazygus veins (systemic).
• In portal hypertension, these anastomotic veins dilate, forming esophageal varices.

Lymphatic Course

• Lymphatics run longitudinally within the submucosa before draining into regional lymph nodes.
• Submucosal extension of tumors is common in esophageal carcinoma.

Surgical Considerations

• Surgical anastomosis in the esophagus carries a high risk of leakage because the muscular layer is thin, weak (poor suture holding), the esophagus lacks a serous covering (except for abdominal), and it has a poor blood supply.

Congenital Anomalies

Esophageal Atresia Description

• Atresia with or without tracheo-esophageal fistula (TOF)
• Esophageal stenosis or short esophagus with hiatus hernia
• Esophageal diverticula
• Dysphagia Lusoria

Atresia with or without Tracheo-Esophageal Fistula

• Definition: Congenital anomaly characterized by failure of complete canalization of a segment in the esophagus with or without TOF.
• Causes: Genetic, due to chromosomal anomalies (e.g., 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 trachea, distal segment ends blindly.
  • Type III (1%): Both segments open into the trachea.
  • Type IV (8%): Both segments end blindly, mid-esophagus is absent (atresia without fistula).
  • Type V (4%): TOF with intact esophagus (fistula without atresia), "H-shaped."

Clinical Picture (Esophageal Atresia)

• More common in males.
• Symptoms and signs:
  • Newborn regurgitates 1st and every feed.
  • Choking, coughing, and cyanosis occur during feeding.
  • Accumulation of saliva in the mouth and inability to swallow.
  • Aspiration pneumonia and failure of feeding lead to dehydration, hypoglycemia, and hypokalaemia.
• Manifested at birth.

Associated Anomalies

• Associated congenital anomalies grouped as VACTERL:
  • Vertebral: Fused or hemivertebrae.
  • Anorectal: Imperforate anus.
  • Cardiac: VSD (Ventricular Septal Defect).
  • Tracheal: TOF and tracheomalacia.
  • Esophageal: Atresia.
  • Renal: Single kidney or VUR (Vesicoureteral Reflux).
  • Limb: Absent thumb, radial dysplasia.

Investigations

• Clinically: Failure of a nasogastric tube (10F) to pass into the stomach.
• Radiologically:
  • Plain X-ray in erect position: Presence or absence of gas in the stomach, presence of fistula to lower pouch or blind lower pouch.
  • Barium swallow: Through a catheter using Lipidol.
  • Tracheoscopy: Evaluates site/number TOF and trachea structure (tracheomalacia).
  • Baby gram: Confirms associated congenital anomalies.

Management

• Treatment:
  • Keep infant flat and in lateral position to avoid secretion accumulation in the pharynx.
  • Use suction to clear secretions from the upper esophageal pouch.
  • Surgery:
    • Aim: Restore continuity of the esophagus.
    • Technique:
      • If a fistula exists: Esophagus is cut from the trachea.
      • No gap between upper and lower esophageal segments: Anastomosis is performed around a catheter.
      • Large gap: Colon bypass is performed at one year of age.

Dysphagia Lusoria (Vascular Compression)

• Definition: Compression on the esophagus by congenital abnormal vessels.
  • Double aortic arch: Encircling the esophagus.
  • Right subclavian artery arising from descending aorta results in the obstruction of the trachea and esophagus.

Clinical Picture

• Often asymptomatic.
• May manifest at 45-50 years old: Atherosclerosis develops, causing rigid arterial wall which compresses the esophagus and trachea, leading to dysphagia, dyspnea & stridor.

Investigations

• Barium swallow: Posterior indentation of the esophagus.

Treatment

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