Esophagus

The oesophagus is a muscular tube that conveys food and fluids from the oropharynx to the stomach.

Gross anatomy

The oesophagus is 23-37 cm long with a diameter of 1-2 cm and is divided into three parts:

• cervical: continuous with the oropharynx, commences at the lower border of cricoid cartilage (at level of C5/6) or cricopharyngeus muscle
• thoracic: from thoracic aperture (T1) to the oesophageal hiatus (T11)
• abdominal: from oesophageal hiatus and is continuous with the cardia of the stomach at the gastro-oesophageal junction

It courses inferiorly to the left of the midline in the neck and superior mediastinum returning to the midline at T5 before coursing to the left again of the midline in the posterior mediastinum and in its inferior aspect curving anteriorly to pass through the diaphragm into the abdominal cavity. 

There are three normal oesophageal constrictions that should not be confused for pathological constrictions:

• cervical constriction: due to cricoid cartilage at the level of C5/6
• thoracic constriction: due to aortic arch at the level of T4/5
• abdominal constriction: at oesophageal hiatus at T10/11

Relations

• posteriorly: vertebral column; descending aorta; thoracic duct (at thoracic plane); accessory hemiazygos and hemiazygos veins (at T8/9)
• anteriorly: trachea (to T4/5); recurrent laryngeal nerves (in tracheo-oesophageal groove); left main bronchus; left atrium
• left lateral: lung; pleura; aorta; left subclavian artery; thoracic duct
• right lateral: lung; pleura; azygos vein

Blood supply

• arterial supply
  • upper third: inferior thyroid artery
  • middle third: oesophageal branches of the thoracic aorta
  • lower third: oesophageal branches of the left gastric artery (site of portal-systemic collateral pathway)
• venous drainage
  • upper third: inferior thyroid veins to brachiocephalic veins
  • middle third: azygos vein to SVC
  • lower third: left gastric vein to portal vein

• sympathetic trunk (sympathetic fibres)
• vagal plexus (parasympathetic fibres)

Lymphatic drainage

Follows arterial supply:

• upper third: deep cervical lymph nodes
• middle third: posterior mediastinal lymph nodes
• lower third: left gastric and coeliac group lymph nodes

Histology

The oesophagus is made up of five layers noting there is no serosal layer:

• outer muscularis propria
• inner muscularis propria
• submucosa
• muscularis mucosae
• mucosa
  • stratified squamous epithelium that abruptly changes to columnar epithelium in the lower oesophagus

Variant anatomy

• oesophageal bronchus
• oesophageal atresia
• aberrant right subclavian artery passing anterior or posterior to the oesophagus

Radiographic appearance

Barium swallow

Barium swallow is the main radiological method of assessing the oesophagus. Double contrast oesophagogram using gas forming crystals and barium contrast are used to distend the oesophagus and coat the mucosa. 

Endoscopic ultrasonography

Endoscopic ultrasonography is used for evaluation of the depth of the oesophageal tumor.

CT

• 80% will contain air allowing for appreciation of wall if there is enough surrounding mediastinal fat
• if collapsed will appear as round or ovoid

MRI

• T1: isointense to muscle
• T2: hyperintense to muscle

PET/CT

For staging of oesophageal cancer.

Related pathology

• oesophageal cancer
• benign oesophageal neoplasms
• hiatus hernia
• achalasia
  • corkscrew oesophagus
• GORD
  • feline oesophagus
• oesophageal rupture
  • Boerhaave syndrome
• oesophageal stricture
  • oesophageal web
  • Schatzki ring