Esophagus | pacs

Imaging of

the oesophagus: beyond cancer. Anatomy and histology of the oesophagus

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The esophagus is a muscular tube that conveys food and fluids from the pharynx to the stomach.

Gross anatomy

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

cervical: continuous with the hypopharynx, commences at the lower border of cricoid cartilage (at level of C5/6) or cricopharyngeus muscle
thoracic: from superior thoracic aperture (T1) to the esophageal hiatus (T10) in the diaphragm which covers the inferior thoracic aperture
abdominal: from esophageal hiatus and is continuous with the cardia of the stomach at the gastro-esophageal junction

The cervical esophagus begins at the upper esophageal sphincter, which is formed by the cricopharyngeus muscle .

The esophagus then descends to the left of the midline through the neck and superior mediastinum, returning to the midline at T5, before coursing to the left of the midline once more, in the posterior mediastinum. The distal thoracic esophagus then curves anteriorly to pass through the diaphragm into the abdominal cavity.

The lower esophageal sphincter, also known as the phrenic ampulla or the esophageal vestibule, represents a 2-4 cm long dilatation between the A-ring and B-ring .

There are three normal esophageal 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 esophageal 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-esophageal groove); left main bronchus; left atrium
left lateral: lung; pleura; aorta; left subclavian artery; thoracic duct
right lateral: lung; pleura; azygos vein

Arterial supply

upper third: inferior thyroid artery
middle third: esophageal branches of the thoracic aorta
lower third: esophageal branches of the left gastric artery

Venous drainage

upper third: inferior thyroid veins to brachiocephalic veins
middle third: azygos vein to SVC
lower third: left gastric vein to portal vein (site of portal-systemic collateral pathway)

Lymphatic drainage

Follows arterial supply:

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

Innervation

sympathetic trunk (sympathetic fibers)
vagal plexus (parasympathetic fibers)

Histology

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

outer longitudinal muscularis propria
inner circular muscularis propria (in the upper 1/3 of the esophagus this layer is composed of striated (voluntary) muscle while the lower 2/3 is smooth muscle)
submucosa
muscularis mucosae
mucosa
- stratified squamous epithelium that abruptly changes to columnar epithelium in the lower esophagus

Variant anatomy

esophageal bronchus
esophageal atresia
aberrant right subclavian artery passing anterior or posterior to the esophagus

Radiographic appearance

Barium swallow

modified barium swallow used to evaluate pharyngeal motility during swallowing, the procedure utilizes barium of varying consistencies given by mouth with video recording of swallowing
barium swallow is the main radiological method of assessing the esophagus. Double contrast esophagogram using gas-forming crystals and barium contrast are used to distend the esophagus and coat the mucosa.