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Esophagus

General

Anatomy & embryology

Author: Elliot Weisenberg, M.D.

Last author update: 1 August 2012

Last staff update: 13 May 2022

Copyright: 2003-2024, PathologyOutlines.com, Inc.

PubMed Search: Esophagus[TI] anatomy[TI]

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Table of Contents

Cite this page: Weisenberg E. Anatomy & embryology. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/esophagusnormalanatomy.html. Accessed March 29th, 2024.

Definition / general

Also called gullet
Muscular tubular structure 25 cm long in adults, 10 - 11 cm in newborns; develops from cranial portion of the foregut; connects pharynx and stomach; has cervical, thoracic and abdominal segments
Main purpose is to propel food from pharynx to stomach via peristalsis; secretes mucin for lubrication and to minimize reflux of gastric contents but has no other significant secretory or absorptive functions
Extends from cricopharyngeus muscle in pharynx (level of C6) to lower esophageal sphinchter at gastroesophageal junction (T11 / T12)

Embryology

Notocord induces formation of foregut from endoderm
At day 21 (end of week 3), lateral walls of foregut develop septa that fuse and divide foregut into esophagus and trachea
At week 4, myenteric plexus develops
At weeks 5 - 6, septation of walls ends; initial lining is stratified columnar epithelium, which proliferates and almost occludes the lumen
At weeks 6 - 7, submucosal plexus develops, circular muscular layer develops
At weeks 6 - 7, epithelial vacuolization appears, vacuoles coalesce to form a single esophageal lumen
At week 8, ciliated cells appear and extend to almost entire columnar epithelium
At week 9, longitudinal muscle layer develops; interstitial cells of Cajal appear
At week 10, a single layer of columnar cells covers entire esophagus
At month 4, submucosal glands appear due to downward growth of columnar cells, extend distally to cardiac mucosa
At month 5, stratified squamous epithelium initially appears in midesophagus and replaces ciliated epithelium cephalad and caudally; proximal esophagus may retain ciliated epithelium at birth
At month 5, upper esophagus has both striated and smooth muscle

Regions (AJCC)

Cervical (lower border of cricoid cartilage to suprasternal notch / thoracic inlet, 5 cm long, begins 15 cm from incisors); contains striated muscle
Upper thoracic (suprasternal notch to tracheal bifurcation, 5 cm long, begins 20 cm from incisors); has striated and smooth muscle
Midthoracic (tracheal bifurcation to diaphragmatic hiatus, 5 cm long, begins 24 cm from incisors); has striated and smooth muscle
Lower thoracic and abdominal (10 cm long, begins 30 cm from incisors); extends past diaphragm to its junction with stomach; has smooth muscle only
Usual points of narrowing (possible sites of food / pill lodging): cricoid cartilage (due to cricopharyngeus muscle), aortic arch, anterior crossing of left main bronchus and left atrium, where it passes through diaphragm
Gastroesophageal junction: traditionally defined as macroscopic point of flaring of tubular esophagus or proximal limit of gastric rugal folds; endoscopic definition is Z ("zigzag") line at irregular boundary of squamous and columnar mucosa in distal esophagus, which is usually 2 - 3 cm proximal to macroscopic GE junction; histologic definition is proximal limit of gastric oxyntic (fundic) mucosa (Hum Pathol 2006;37:40)
Distal 1 - 2 cm of esophagus is often composed of cardiac or cardiac - oxyntic type of mucosa; there is no consensus if this is normal or due to reflux esophagitis
Esophageal sphincters: two areas of high pressure at rest (physiologic, not anatomic sphincters); upper esophageal sphincter is at cricopharyngeus and inferior pharyngeal constrictor muscles; lower esophageal sphincter is 2 - 4 cm proximal to esophagogastric junction at level of diaphragm (composed of intrinsic esophageal muscles, sling fibers of proximal stomach and crural diaphragm)
Vagotomy does NOT affect tone of lower esophageal sphincter; tone is affected by gastrin, acetylcholine and serotonin

Vessels and nerves

Arterial blood supply: cervical region - inferior thyroid artery; upper thoracic - bronchial and intercostal arteries; lower thoracic - aortic branches; abdominal - left gastric and inferior phrenic arteries; infarction is rare due to numerous anastomoses
Venous drainage: extensive submucosal venous plexus communicates with periesophageal veins; flows into inferior thyroid (upper 1/3), azygous (middle 1/3) and gastric veins (lower 1/3); azygous vein empties into superior vena cava and gastric veins into portal system; this connection between caval and portal venous systems explains esophageal varices due to portal hypertension
Nerves: left and right vagus nerves run lateral to esophagus, form plexi along anterior and posterior surfaces, then reunite to form anterior and posterior vagal trunks to stomach; have parasympathetic and sympathetic innervation
Lymphatic drainage: freely anastomosing networks in submucosa, muscularis propria and occasionally lamina propria; facilitate lengthwise tumor dissemination; upper third drains into paratracheal and internal jugular nodes, middle third to mediastinal nodes, lower third to nodes around aorta and celiac axis
Adjacent structures: cervical esophagus lies in posterior mediastinum, posterior to trachea and thyroid gland; is bounded by left and right recurrent laryngeal nerves and carotid sheaths; distal esophagus is posterior to left atrium and bounded by azygous veins; passes through opening in diaphragm called the hiatus
Incisura / angle of His: left side of esophagus forms sharp angle where it joins the stomach

Diagrams / tables

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