ESOPHAGUS
GROSS ANATOMY
It is a muscular tube about 25 cm long and 2 cm in diameter, which extends from the
oropharynx to the cardiac part of the stomach.Initially the esophagus is anterior to the vertebrae,
then it slightly gets to the left after crossing esophagial hiatus.It's right border is continuous
with lesser curvature of stomach but its left border is separated from fundus by cardiac notch
(angle of His)
PARTS
It has 3 parts:
● Cervical.
● Thoracic.
● Abdominal(intraperitoneal)
SPHINCTERS
● Pharyngoesophageal sphincter which is surrounded by cricopharyngeus muscle.
● Gastroesophageal sphincter where Z line marks the junction of esophagus and
stomach.
CONSTRICTIONS
It has 3 constrictions:
● At the level of commencement of esophagus(cervical).
● At the point where left bronchus and aorta crosses the esophagus(thoracic)
● At esophageal hiatus due to phrenoesophageal ligament(diaphragmatic)
ARTERIAL SUPPLY
Esophageal branches of the following arteries:
● Inferior thyroid artery
● Left Inferior phrenic artery
● Left gastric artery
● Thoracic aorta
● Bronchial artery
VENOUS DRAINAGE
● Azygos vein
● Hemiazygos vein
● Left gastric vein
● Bronchial vein
● Inferior thyroid vein
LYMPHATICS
lymphatic drainage of the abdominal part of esophagus is into the left gastric lymph nodes
which drains to celiac lymph nodes
INNERVATION
CERVICAL PART
● Sympathetic by cervical sympathetic trunk
● Parasympathetic by recurrent laryngeal nerve.
THORACIC PART
Esophageal plexus which is formed by:
● Right vagus nerve(parasympathetic)
● Left vagus nerve(parasympathetic)
● Greater splanchnic nerve(sympathetic)
From this plexus , vagal trunks are arisen.Anterior trunk is mostly formed by the left vagus
nerve and posterior trunk is mostly formed by the right vagus nerve.
ABDOMINAL PART
● Sympathetic by thoracic spinal nerves.
● Parasympathetic by esophageal plexus.
MOTOR INNERVATION
It is done through:
● Somatic efferents of vagus nerve
● Visceral efferents of vagus nerve.
SENSORY INNERVATION
It is done through:
● Pain through splanchnic nerves and sympathetic trunk.
● Reflexes through visceral afferents of the vagus nerve.
RELATION
● Anteriorly by trachea and pericardium
● Posteriorly by azygos vein, hemiazygos vein, accessory azygos vein. Aorta, thoracic
duct.
● Left side by aortic arch
● Right side by azygos arch
HISTOLOGY
Esophageal lumen is seen to be collapsed in cross-section, due to presence of longitudinal
mucosal folds with intervening grooves, but during swallowing, these folds disappear.
LAYERS
MUCOSA
It is lined by stratified squamous nonkeratinized epithelium.Upper and lower thirds of the lamina
propria of esophagus consists of mucus-secreting simple branched tubular glands, called
esophageal cardiac glands.Muscularis mucosae consists of SM fibers which run in
longitudinal direction. This coat is thicker in the esophagus than any other segment of GIT and it
is responsible for folds in mucosa of esophagus.
SUBMUCOSA
It is dense irregular CT which contains blood vessels, lymph vessels and the Meissner plexus
of nerves.Special feature is that it lodges mucus-secreting, branched tubuloacinar glands,
called esophageal glands proper. The ducts of these glands pass through mucosa to open
into the lumen, lubricating and making it slippery.
MUSCULARIS EXTERNA
It consists of outer longitudinal and inner circular layers.In the upper third, only skeletal
muscle is present while in the inferior third only smooth muscle is present. The middle third,
combination of both is present
Myenteric plexus is found between longitudinal and circular layer of muscles
At the lower end of the esophagus, a bundle of circular smooth muscle fibers form a sphincter
which is known as lower esophageal sphincter which is formed by right crus of diaphragm.
ADVENTITIA AND SEROSA
In cervical and thoracic regions, it is covered by adventitia of loose connective tissue and the
abdominal part is covered with serosa.
