HOME

TheInfoList




The esophagus (
American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of variety (linguistics), varieties of the English language native to the United States. Currently, American English is the m ...
) or oesophagus (
British English British English (BrE) is the standard dialect A standard language (also standard variety, standard dialect, and standard) is a language variety that has undergone substantial codification of grammar and usage and is employed by a populatio ...
; both ), informally known as the food pipe or gullet, is an
organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's tissues can be broadly cate ...
in
vertebrate Vertebrates () comprise all species of animal Animals (also called Metazoa) are multicellular A multicellular organism is an organism In biology, an organism () is any organic, life, living system that functions as an indiv ...
s through which
food Food is any substance consumed to provide Nutrient, nutritional support for an organism. Food is usually of plant, animal or Fungus, fungal origin, and contains essential nutrients, such as carbohydrates, fats, protein (nutrient), proteins, vi ...

food
passes, aided by
peristaltic contractions
peristaltic contractions
, from the
pharynx The pharynx (plural: pharynges) is the part of the throat behind the human mouth, mouth and nasal cavity, and above the esophagus and trachea – the tubes going down to the stomach and the lungs. It is found in vertebrates and invertebrates, thou ...
to the
stomach The stomach is a muscular, in the of humans and many other animals, including several s. The stomach has a dilated structure and functions as a vital organ. In the digestive system the stomach is involved in the second phase of digestion, ...

stomach
. The esophagus is a fibromuscular tube, about long in adults, that travels behind the
trachea The trachea, also known as the windpipe, is a cartilaginous Cartilage (cartilaginous tissue) is a resilient and smooth elastic tissue, rubber-like padding that covers and protects the ends of long bone A bone is a Stiffness, rigid tissue ...

trachea
and
heart The heart is a muscular MUSCULAR (DS-200B), located in the United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain,Usage is mixed. The Guardian' and Telegraph' use ...

heart
, passes through the
diaphragm Diaphragm may refer to: * Diaphragm (anatomy) or thoracic diaphragm, a thin sheet of muscle between the thorax and the abdomen * Diaphragm (optics), a stop in the light path of a lens, having an aperture that regulates the amount of light that pass ...
, and empties into the uppermost region of the
stomach The stomach is a muscular, in the of humans and many other animals, including several s. The stomach has a dilated structure and functions as a vital organ. In the digestive system the stomach is involved in the second phase of digestion, ...

stomach
. During swallowing, the
epiglottis The epiglottis is a leaf-shaped flap in the throat In vertebrate anatomy, the throat is the front part of the neck, internally positioned in front of the vertebra, vertebrae. It contains the Human pharynx, pharynx and larynx. An important secti ...

epiglottis
tilts backwards to prevent food from going down the
larynx The larynx (), commonly called the voice box, is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exist ...

larynx
and lungs. The word ''oesophagus'' is from Ancient Greek οἰσοφάγος (oisophágos), from οἴσω (oísō), future form of φέρω (phérō, “I carry”) + ἔφαγον (éphagon, “I ate”). The wall of the esophagus from the lumen outwards consists of
mucosa A mucous membrane or mucosa is a membrane A membrane is a selective barrier; it allows some things to pass through but stops others. Such things may be molecules, ions, or other small particles. Biological membranes include cell membranes (ou ...

mucosa
,
submucosa The submucosa (or tela submucosa) is a thin layer of tissue (biology), tissue in various organ (anatomy), organs of the gastrointestinal tract, gastrointestinal, respiratory tract, respiratory, and genitourinary system, genitourinary tracts. It is ...
(connective tissue), layers of muscle fibers between layers of
fibrous tissue Fiber or fibre (from la, fibra, links=no) is a #Natural fibers, natural or #Man-made fibers, man-made substance that is significantly longer than it is wide. Fibers are often used in the manufacture of other materials. The strongest engineeri ...
, and an outer layer of connective tissue. The mucosa is a
stratified squamous epithelium A stratified squamous epithelium consists of squamous (flattened) epithelial cell Epithelium is one of the four basic types of animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biolo ...

stratified squamous epithelium
of around three layers of squamous cells, which contrasts to the single layer of columnar cells of the stomach. The transition between these two types of epithelium is visible as a zig-zag line. Most of the muscle is
smooth muscle Smooth muscle is an involuntary non-striated muscle Striated muscle tissue is a muscle tissue Muscle tissue is a soft tissue that composes muscles in animal bodies, and gives rise to muscles' ability to contract. It is also referred to as myo ...

smooth muscle
although
striated muscle Striated muscle tissue is a muscle tissue that features repeating functional units called sarcomeres. The presence of sarcomeres manifests as a series of bands visible along the muscle fibers, which is responsible for the striated appearance obser ...

striated muscle
predominates in its upper third. It has two muscular rings or
sphincter A sphincter is a circular muscle Skeletal muscles (commonly referred to as muscles) are organs An organ is a group of tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A give ...
s in its wall, one at the top and one at the bottom. The lower sphincter helps to prevent reflux of acidic stomach content. The esophagus has a rich blood supply and venous drainage. Its smooth muscle is innervated by involuntary nerves ( sympathetic nerves via the
sympathetic trunk The sympathetic trunks (sympathetic chain, gangliated cord) are a paired bundle of nerve fibers that run from the base of the skull The skull is a bone A bone is a rigid tissue Tissue may refer to: Biology * Tissue (biology), an ensemb ...

sympathetic trunk
and
parasympathetic nerve The parasympathetic nervous system (PSNS) is one of the three divisions of the autonomic nervous system The autonomic nervous system (ANS), formerly the vegetative nervous system, is a division of the peripheral nervous system that supplies smo ...
s via the
vagus nerve The vagus nerve, historically cited as the pneumogastric nerve, is the tenth cranial nerve Cranial nerves are the nerve A nerve is an enclosed, cable-like bundle of nerve fibers called axon An axon (from Greek ἄξων ''áxōn'', axi ...
) and in addition voluntary nerves (
lower motor neurons Lower motor neurons (LMNs) are motor neurons located in either the anterior grey column, anterior root of spinal nerve, anterior nerve roots (spinal lower motor neurons) or the cranial nerve nucleus, cranial nerve nuclei of the brainstem and crania ...
) which are carried in the vagus nerve to innervate its striated muscle. The esophagus passes through the thoracic cavity into the
diaphragm Diaphragm may refer to: * Diaphragm (anatomy) or thoracic diaphragm, a thin sheet of muscle between the thorax and the abdomen * Diaphragm (optics), a stop in the light path of a lens, having an aperture that regulates the amount of light that pass ...
into the stomach. The esophagus may be affected by
gastric reflux Gastroesophageal reflux disease (GERD), is a chronic condition in which stomach contents rise up into the esophagus The esophagus (American English) or oesophagus (British English; American and British English spelling differences#ae and ...

gastric reflux
,
cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumor A benign tumor is a mass of cells Cell most often refers to: * Cell (biolo ...
, prominent dilated blood vessels called varices that can bleed heavily,
tears Tears are a clear liquid secreted by the lacrimal glands (tear gland) found in the eyes of all Mammal, land mammals (except for goats and rabbits). Their functions include lubricating the eyes (basal tears), removing irritants (reflex tears), and ...
, constrictions, and disorders of motility. Diseases may cause difficulty swallowing (
dysphagia Dysphagia is difficulty in swallowing Swallowing, sometimes called deglutition in scientific contexts, is the process in the human or animal body that allows for a substance to pass from the mouth, to the pharynx, and into the esophagus, while ...
), painful swallowing (
odynophagia Odynophagia is pain when swallowing. The pain may be felt in the mouth or throat and can occur with or without difficulty swallowing. The pain may be described as an ache, burning sensation, or occasionally a stabbing pain that radiates to the b ...
),
chest pain Chest pain is pain or discomfort in the chest, typically the front of the chest. It may be described as sharp, dull, pressure, heaviness or squeezing. Associated symptoms may include pain in the shoulder, arm, upper abdomen, or jaw, along with na ...
, or cause no symptoms at all. Clinical investigations include
X-rays An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Moti ...
when swallowing
barium sulfate Barium sulfate (or sulphate) is the inorganic compound In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, p ...
,
endoscopy An endoscopy (''looking inside'') is a procedure used in medicine Medicine is the science Science () is a systematic enterprise that builds and organizes knowledge Knowledge is a familiarity, awareness, or understanding of someon ...

endoscopy
, and
CT scan A CT scan or computed tomography scan (formerly known as computed axial tomography or CAT scan) is a medical image, imaging Scientific technique, technique used in radiology to obtain detailed internal images of the body noninvasively for Diagno ...

CT scan
s. Surgically, the esophagus is difficult to access in part due to its position between critical organs and directly between the sternum and spinal column.


Structure

The esophagus is one of the upper parts of the
digestive system The human digestive system consists of the human gastrointestinal tract, gastrointestinal tract plus the accessory organs of digestion (the tongue, salivary glands, pancreas, liver, and gallbladder). Digestion involves the breakdown of food in ...

digestive system
. There are
taste bud Taste buds contain the taste receptor cells, which are also known as gustatory cells. The taste receptor A taste receptor is a type of Receptor (biochemistry), cellular receptor which facilitates the sensation of taste. When food or other su ...

taste bud
s on its upper part. It begins at the back of the mouth, passing downward through the rear part of the
mediastinum The mediastinum (from ) is the central compartment of the thoracic cavity 250px, The picture displays the Mediastinum on sagittal plane, Thoracic diaphragm">sagittal_plane.html" ;"title="Mediastinum on sagittal plane">Mediastinum on sagittal p ...

mediastinum
, through the
diaphragm Diaphragm may refer to: * Diaphragm (anatomy) or thoracic diaphragm, a thin sheet of muscle between the thorax and the abdomen * Diaphragm (optics), a stop in the light path of a lens, having an aperture that regulates the amount of light that pass ...
, and into the stomach. In humans, the esophagus generally starts around the level of the sixth
cervical vertebra In tetrapod Tetrapods (; from Greek 'four' and 'foot') are four-limbed animals constituting the superclass Tetrapoda . It includes extant and extinct amphibians, reptiles (including dinosaurs and therefore birds), and synapsids (including ...

cervical vertebra
behind the
cricoid cartilage The cricoid cartilage , or simply cricoid (from the Greek ''krikoeides'' meaning "ring-shaped") or cricoid ring, is the only complete ring of cartilage Cartilage (cartilaginous tissue) is a resilient and smooth elastic tissue Elastic fibers (or ...
of the
trachea The trachea, also known as the windpipe, is a cartilaginous Cartilage (cartilaginous tissue) is a resilient and smooth elastic tissue, rubber-like padding that covers and protects the ends of long bone A bone is a Stiffness, rigid tissue ...

trachea
, enters the diaphragm at about the level of the tenth thoracic vertebra, and ends at the
cardia The stomach is a muscular, hollow organ An organ is a group of tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's tissues can be broadly categorized as parenchy ...

cardia
of the stomach, at the level of the eleventh thoracic vertebra. The esophagus is usually about 25 cm (10 in) in length. Many
blood vessel The blood vessels are the components of the circulatory system The circulatory system, also called the cardiovascular system or the vascular system, is an organ system An organ system is a biological system A biological system is a comp ...
s serve the esophagus, with blood supply varying along its course. The upper parts of the esophagus and the upper esophageal sphincter receive blood from the
inferior thyroid artery The inferior thyroid artery is an artery An artery (plural arteries) () is a blood vessel that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry oxygenated blood; the two exce ...
, the parts of the esophagus in the thorax from the
bronchial arteries In human anatomy The human body is the structure of a human being. It is composed of many different types of cells that together create tissues and subsequently organ systems. They ensure homeostasis In biology Biology is the natural ...
and branches directly from the
thoracic aorta The descending thoracic aorta is a part of the aorta The aorta ( ) is the main and largest artery An artery (plural arteries) () is a blood vessel that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain ...

thoracic aorta
, and the lower parts of the esophagus and the lower esophageal sphincter receive blood from the
left gastric artery In human anatomy The human body is the structure of a human being Humans (''Homo sapiens'') are the most abundant and widespread species In biology, a species is the basic unit of biological classification, classification and a ...
and the left inferior phrenic artery. The venous drainage also differs along the course of the esophagus. The upper and middle parts of the esophagus drain into the and
hemiazygos vein The hemiazygos vein (vena azygos minor inferior) is a vein running superiorly in the lower thoracic region, just to the left side of the vertebral column. Structure The hemiazygos vein and the accessory hemiazygos vein, when taken together, essent ...
s, and blood from the lower part drains into the
left gastric vein The left gastric vein (or coronary vein) is a vein that derives from tributaries draining the lesser curvature of the stomach The stomach is a muscular, hollow organ in the gastrointestinal tract of humans and many other animals, including s ...
. All these veins drain into the
superior vena cava The superior vena cava (SVC) is the anatomical terms of location#Superior and inferior, superior of the two venae cavae, the great vein, venous trunks that return deoxygenated blood from the circulatory system, systemic circulation to the atrium ...
, with the exception of the left gastric vein, which is a branch of the
portal vein The portal vein or hepatic portal vein (HPV) is a blood vessel The blood vessels are the components of the circulatory system The circulatory system, also called the cardiovascular system or the vascular system, is an organ system that ...
. Lymphatically, the upper third of the esophagus drains into the
deep cervical lymph node The deep cervical lymph nodes are a group of cervical lymph nodes Cervical lymph nodes are lymph node A lymph node, or lymph gland, is a kidney-shaped Organ (anatomy), organ of the lymphatic system, and the adaptive immune system. A large num ...
s, the middle into the superior and posterior mediastinal lymph nodes, and the lower esophagus into the
gastric The stomach is a muscular, hollow organ in the gastrointestinal tract The gastrointestinal tract, (GI tract, GIT, digestive tract, digestion tract, alimentary canal) is the tract from the mouth to the anus which includes all the organs ...
and
celiac lymph nodes The celiac lymph nodes are associated with the branches of the celiac artery The celiac () artery (also spelled ''coeliac''), also known as the celiac trunk or truncus coeliacus, is the first major branch of the abdominal aorta. It is about 1.25& ...
. This is similar to the lymphatic drainage of the abdominal structures that arise from the
foregut The foregut is the anterior part of the alimentary canal, from the mouth to the duodenum at the entrance of the bile duct. Beyond the stomach, the foregut is attached to the abdominal walls by mesentery. The foregut arises from the endoderm, develo ...
, which all drain into the celiac nodes. ;Position The upper esophagus lies at the back of the mediastinum behind the
trachea The trachea, also known as the windpipe, is a cartilaginous Cartilage (cartilaginous tissue) is a resilient and smooth elastic tissue, rubber-like padding that covers and protects the ends of long bone A bone is a Stiffness, rigid tissue ...

trachea
, adjoining along the tracheoesophageal stripe, and in front of the erector spinae muscles and the
vertebral column The vertebral column, also known as the backbone or spine, is part of the axial skeleton Axial may refer to: * one of the describing relationships in an animal body * and submarine volcano off Oregon, USA * , a ghost town * In geometry: :* ...

vertebral column
. The lower esophagus lies behind the
heart The heart is a muscular MUSCULAR (DS-200B), located in the United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain,Usage is mixed. The Guardian' and Telegraph' use ...

heart
and curves in front of the
thoracic aorta The descending thoracic aorta is a part of the aorta The aorta ( ) is the main and largest artery An artery (plural arteries) () is a blood vessel that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain ...

thoracic aorta
. From the bifurcation of the trachea downwards, the esophagus passes behind the right
pulmonary artery A pulmonary artery is an artery An artery (plural arteries) () is a blood vessel The blood vessels are the components of the circulatory system The circulatory system, also called the cardiovascular system or the vascular system, is ...

pulmonary artery
, left main bronchus, and
left atrium The atrium (Latin ātrium, “entry hall”) is the upper chamber through which blood enters the ventricles of the heart The heart is a cardiac muscle, muscular Organ (biology), organ in most animals, which pumps blood through the blood ...
. At this point, it passes through the diaphragm. The
thoracic duct In human anatomy Anatomy (Greek ''anatomē'', 'dissection') is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science which deals with the structural organization o ...
, which drains the majority of the body's
lymph Lymph (from Latin, ''lympha'' meaning "water") is the fluid that flows through the lymphatic system The lymphatic system, or lymphoid system, is an organ system in vertebrates that is part of the circulatory system and the immune system. It i ...
, passes behind the esophagus, curving from lying behind the esophagus on the right in the lower part of the esophagus, to lying behind the esophagus on the left in the upper esophagus. The esophagus also lies in front of parts of the
hemiazygos vein The hemiazygos vein (vena azygos minor inferior) is a vein running superiorly in the lower thoracic region, just to the left side of the vertebral column. Structure The hemiazygos vein and the accessory hemiazygos vein, when taken together, essent ...
s and the intercostal veins on the right side. The
vagus nerve The vagus nerve, historically cited as the pneumogastric nerve, is the tenth cranial nerve Cranial nerves are the nerve A nerve is an enclosed, cable-like bundle of nerve fibers called axon An axon (from Greek ἄξων ''áxōn'', axi ...
divides and covers the esophagus in a
plexus A plexus (from the Latin for "braid") is a branching network of vessels or Nerve, nerves. The vessels may be Blood vessel, blood vessels (veins, capillaries) or Lymphatic vessel, lymphatic vessels. The nerves are typically Axon, axons outside the ...
. ;Constrictions The esophagus has four points of constriction. When a corrosive substance, or a solid object is swallowed, it is most likely to lodge and damage one of these four points. These constrictions arise from particular structures that compress the esophagus. These constrictions are: * At the start of the esophagus, where the
laryngopharynx The pharynx (plural: pharynges) is the part of the throat In vertebrate anatomy, the throat is the front part of the neck, positioned in front of the vertebra. It contains the Human pharynx, pharynx and larynx. An important section of it is the ...
joins the esophagus, behind the
cricoid cartilage The cricoid cartilage , or simply cricoid (from the Greek ''krikoeides'' meaning "ring-shaped") or cricoid ring, is the only complete ring of cartilage Cartilage (cartilaginous tissue) is a resilient and smooth elastic tissue Elastic fibers (or ...
* Where it is crossed on the front by the
aortic arch The aortic arch, arch of the aorta, or transverse aortic arch () is the part of the aorta The aorta ( ) is the main and largest in the , originating from the of the and extending down to the , where it into two smaller arteries (the ). T ...

aortic arch
in the superior
mediastinum The mediastinum (from ) is the central compartment of the thoracic cavity 250px, The picture displays the Mediastinum on sagittal plane, Thoracic diaphragm">sagittal_plane.html" ;"title="Mediastinum on sagittal plane">Mediastinum on sagittal p ...

mediastinum
* Where the esophagus is compressed by the left main
bronchus A bronchus is a passage or airway in the respiratory system The respiratory system (also respiratory apparatus, ventilatory system) is a biological system A biological system is a complex network Network and networking may refer to: Arts, e ...

bronchus
in the posterior mediastinum * The
esophageal hiatus In human anatomy, the esophageal hiatus is an opening in the diaphragm through which the esophagus The esophagus (American English) or oesophagus (British English; American and British English spelling differences#ae and oe, see spelling dif ...
, where it passes through the
diaphragm Diaphragm may refer to: * Diaphragm (anatomy) or thoracic diaphragm, a thin sheet of muscle between the thorax and the abdomen * Diaphragm (optics), a stop in the light path of a lens, having an aperture that regulates the amount of light that pass ...
in the posterior mediastinum


Sphincters

The esophagus is surrounded at the top and bottom by two muscular rings, known respectively as the upper esophageal sphincter and the lower esophageal sphincter. These
sphincter A sphincter is a circular muscle Skeletal muscles (commonly referred to as muscles) are organs An organ is a group of tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A give ...
s act to close the esophagus when food is not being swallowed. The upper esophageal sphincter is an anatomical sphincter, which is formed by the lower portion of the inferior pharyngeal constrictor, also known as the cricopharyngeal sphincter due to its relation with
cricoid cartilage The cricoid cartilage , or simply cricoid (from the Greek ''krikoeides'' meaning "ring-shaped") or cricoid ring, is the only complete ring of cartilage Cartilage (cartilaginous tissue) is a resilient and smooth elastic tissue Elastic fibers (or ...
of the
larynx The larynx (), commonly called the voice box, is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exist ...

larynx
anteriorly. However, the lower esophageal sphincter is not an anatomical but rather a functional sphincter, meaning that it acts as a sphincter but does not have a distinct thickening like other sphincters. The upper esophageal sphincter surrounds the upper part of the esophagus. It consists of
skeletal muscle Skeletal muscles (commonly referred to as muscles) are Organ (biology), organs of the vertebrate muscular system that are mostly attached by tendons to bones of the skeleton. The muscle cells of skeletal muscles are much longer than in the other ...

skeletal muscle
but is not under . Opening of the upper esophageal sphincter is triggered by the
swallowing Swallowing, sometimes called deglutition in scientific contexts, is the process in the human or animal body that allows for a substance to pass from the mouth In animal anatomy Anatomy (Greek ''anatomē'', 'dissection') is the branch of ...
reflex In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mechanism ...

reflex
. The primary muscle of the upper esophageal sphincter is the cricopharyngeal part of the
inferior pharyngeal constrictor The inferior pharyngeal constrictor muscle is a skeletal muscle of the neck. It is the thickest of the three outer pharyngeal muscles. It arises from the sides of the cricoid cartilage and the thyroid cartilage. It is supplied by the vagus nerve (C ...
. The lower esophageal sphincter, or gastroesophageal sphincter, surrounds the lower part of the esophagus at the junction between the esophagus and the stomach. It is also called the cardiac sphincter or cardioesophageal sphincter, named from the adjacent part of the stomach, the ''
cardia The stomach is a muscular, hollow organ An organ is a group of tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's tissues can be broadly categorized as parenchy ...

cardia
''. Dysfunction of the gastroesophageal sphincter causes gastroesophageal
reflux Reflux is a technique involving the condensation Condensation is the change of the state of matter In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (phy ...

reflux
, which causes
heartburn Heartburn, also known as pyrosis, cardialgia or acid indigestion, is a burning sensation in the central chest or upper central abdomen. The discomfort often rises in the chest and may radiate to the neck, throat, or angle of the arm. Heartbur ...
, and, if it happens often enough, can lead to
gastroesophageal reflux disease Gastroesophageal reflux disease (GERD), is a chronic condition in which stomach contents rise up into the esophagus The esophagus (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States E ...
, with damage of the esophageal mucosa.


Nerve supply

The esophagus is innervated by the vagus nerve and the cervical and thoracic
sympathetic trunk The sympathetic trunks (sympathetic chain, gangliated cord) are a paired bundle of nerve fibers that run from the base of the skull The skull is a bone A bone is a rigid tissue Tissue may refer to: Biology * Tissue (biology), an ensemb ...

sympathetic trunk
. The vagus nerve has a
parasympathetic The parasympathetic nervous system (PSNS) is one of the three divisions of the autonomic nervous system, the others being the sympathetic nervous system and the enteric nervous system. The enteric nervous system is sometimes considered part of t ...
function, supplying the muscles of the esophagus and stimulating glandular contraction. Two sets of nerve fibers travel in the vagus nerve to supply the muscles. The upper striated muscle, and upper esophageal sphincter, are supplied by neurons with bodies in the
nucleus ambiguus The nucleus ambiguus ("ambiguous nucleus" in English) is a group of large motor neuron A motor neuron (or motoneuron or efferent neuron) is a whose is located in the , or the , and whose (fiber) projects to the spinal cord or outside of the s ...
, whereas fibers that supply the smooth muscle and lower esophageal sphincter have bodies situated in the dorsal motor nucleus. The vagus nerve plays the primary role in initiating
peristalsis Peristalsis is a radially symmetrical Symmetry in biology refers to the symmetry observed in organisms, including plants, animals, fungi, and bacteria. External symmetry can be easily seen by just looking at an organism. For example, take ...

peristalsis
. The sympathetic trunk has a sympathetic function. It may enhance the function of the vagus nerve, increasing peristalsis and glandular activity, and causing sphincter contraction. In addition, sympathetic activation may relax the muscle wall and cause blood vessel constriction. Sensation along the esophagus is supplied by both nerves, with gross sensation being passed in the vagus nerve and pain passed up the sympathetic trunk.


Gastro-esophageal junction

The gastro-esophageal junction (also known as the esophagogastric junction) is the junction between the esophagus and the stomach, at the lower end of the esophagus. The pink color of the esophageal mucosa contrasts to the deeper red of the gastric mucosa, and the mucosal transition can be seen as an irregular zig-zag line, which is often called the z-line. Histological examination reveals abrupt transition between the
stratified squamous epithelium A stratified squamous epithelium consists of squamous (flattened) epithelial cell Epithelium is one of the four basic types of animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biolo ...

stratified squamous epithelium
of the esophagus and the
simple columnar epithelium Simple columnar epithelium is a single layer of columnar epithelial cell Epithelium () is one of the four basic types of animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biology), bi ...

simple columnar epithelium
of the
stomach The stomach is a muscular, in the of humans and many other animals, including several s. The stomach has a dilated structure and functions as a vital organ. In the digestive system the stomach is involved in the second phase of digestion, ...

stomach
. Normally, the
cardia The stomach is a muscular, hollow organ An organ is a group of tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's tissues can be broadly categorized as parench ...

cardia
of the stomach is immediately distal to the z-line and the z-line coincides with the upper limit of the gastric folds of the cardia; however, when the anatomy of the mucosa is distorted in
Barrett's esophagus Barrett's esophagus is a condition in which there is an abnormal (metaplastic) change in the mucosal cells lining the lower portion of the esophagus, from normal stratified squamous epithelium to simple columnar epithelium with interspersed goblet ...
the true gastro-eshophageal junction can be identified by the upper limit of the gastric folds rather than the mucosal transition. The functional location of the lower oesophageal sphincter is generally situated about below the z-line.


Microanatomy

The human esophagus has a
mucous membrane A mucous membrane or mucosa is a biological membrane, membrane that lines various cavities in the body and covers the surface of internal organs. It consists of one or more layers of Epithelium, epithelial cells overlying a layer of loose connect ...
consisting of a tough
stratified squamous epithelium A stratified squamous epithelium consists of squamous (flattened) epithelial cell Epithelium is one of the four basic types of animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biolo ...

stratified squamous epithelium
without
keratin Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. Alpha-keratin Alpha-keratin, or α-keratin, is a type of keratin Keratin () is one of a family of fibrous structural proteins known as Scleroprot ...

keratin
, a smooth
lamina propria The lamina propria is a thin layer of connective tissue Connective tissue is one of the many basic types of animal Animals (also called Metazoa) are multicellular A multicellular organism is an organism In biology, an orga ...
, and a
muscularis mucosae The lamina muscularis mucosae (or muscularis mucosae) is a thin layer ( lamina) of muscle Muscle is a soft tissue found in most animals. Muscle cells contain protein Proteins are large biomolecules or macromolecules that are comprised o ...
. The epithelium of the esophagus has a relatively rapid turnover and serves a protective function against the abrasive effects of food. In many animals, the epithelium contains a layer of keratin, representing a coarser diet. There are two types of glands, with mucus-secreting esophageal glands being found in the
submucosa The submucosa (or tela submucosa) is a thin layer of tissue (biology), tissue in various organ (anatomy), organs of the gastrointestinal tract, gastrointestinal, respiratory tract, respiratory, and genitourinary system, genitourinary tracts. It is ...
and esophageal cardiac glands, similar to cardiac glands of the stomach, located in the lamina propria and most frequent in the terminal part of the organ. The
mucus Mucus ( ) is a slippery aqueous secretion produced by, and covering, mucous membrane A mucous membrane or mucosa is a biological membrane, membrane that lines various cavities in the body and covers the surface of internal organs. It consists o ...
from the glands gives a good protection to the lining. The submucosa also contains the
submucosal plexus The submucosal plexus (Meissner's plexus, plexus of the submucosa, plexus submucosus) lies in the submucosa The submucosa (or tela submucosa) is a thin layer of tissue in various organs of the gastrointestinal The gastrointestinal tract, (GI ...
, a network of that is part of the
enteric nervous system The enteric nervous system (ENS) or intrinsic nervous system is one of the main divisions of the autonomic nervous system The autonomic nervous system (ANS), formerly the vegetative nervous system, is a division of the peripheral nervous system ...
. The
muscular layer The muscular layer (muscular coat, muscular fibers, muscularis propria, muscularis externa) is a region of muscle Skeletal muscles (commonly referred to as muscles) are organs An organ is a group of tissues with similar functions. Plant l ...
of the esophagus has two types of muscle. The upper third of the esophagus contains
striated muscle Striated muscle tissue is a muscle tissue that features repeating functional units called sarcomeres. The presence of sarcomeres manifests as a series of bands visible along the muscle fibers, which is responsible for the striated appearance obser ...

striated muscle
, the lower third contains
smooth muscle Smooth muscle is an involuntary non-striated muscle Striated muscle tissue is a muscle tissue Muscle tissue is a soft tissue that composes muscles in animal bodies, and gives rise to muscles' ability to contract. It is also referred to as myo ...

smooth muscle
, and the middle third contains a mixture of both. Muscle is arranged in two layers: one in which the muscle fibers run longitudinal to the esophagus, and the other in which the fibers encircle the esophagus. These are separated by the
myenteric plexus The myenteric plexus (or Auerbach's plexus) provides motor innervation to both layers of the muscular layer The muscular layer (muscular coat, muscular fibers, muscularis propria, muscularis externa) is a region of muscle Skeletal muscles ( ...

myenteric plexus
, a tangled network of nerve fibers involved in the secretion of mucus and in peristalsis of the smooth muscle of the esophagus. The outermost layer of the esophagus is the
adventitia The adventitia, () is the outer layer of fibrous connective tissue surrounding an organ (anatomy), organ. The outer layer of connective tissue that surrounds an artery, or vein – the tunica externa, is also called the ''tunica adventitia''. To ...
in most of its length, with the abdominal part being covered in
serosa In anatomy, serous membrane (or serosa) is a smooth membrane, tissue membrane of mesothelium lining the contents and inside wall of body cavity, body cavities, which secrete serous fluid to allow lubricated sliding (motion), sliding movements betw ...
. This makes it distinct from many other structures in the gastrointestinal tract that only have a serosa.


Development

In early
embryogenesis An embryo is the early stage of development of a multicellular organism A multicellular organism is an organism In biology, an organism () is any organic, life, living system that functions as an individual entity. All organisms ar ...

embryogenesis
, the esophagus develops from the
endoderm Endoderm is the innermost of the three primary germ layer A germ layer is a primary layer of cell (biology), cells that forms during embryonic development. The three germ layers in vertebrates are particularly pronounced; however, all eumetazo ...
al primitive gut tube. The ventral part of the embryo abuts the
yolk sac The yolk sac is a membranous wikt:sac, sac attached to an embryo, formed by cells of the hypoblast adjacent to the embryonic disk. This is alternatively called the umbilical vesicle by the Terminologia Embryologica (TE), though ''yolk sac'' is far ...
. During the second week of embryological development, as the embryo grows, it begins to surround parts of the sac. The enveloped portions form the basis for the adult gastrointestinal tract. The sac is surrounded by a network of
vitelline arteries The vitelline arteries are the arterial counterpart to the vitelline veins. Like the veins, they play an important role in the vitelline circulation of blood to and from the yolk sac of a fetus. They are a branch of the dorsal aorta. They give ris ...
. Over time, these arteries consolidate into the three main arteries that supply the developing gastrointestinal tract: the
celiac artery The celiac () artery (also spelled ''coeliac''), also known as the celiac trunk or truncus coeliacus, is the first major branch of the abdominal aorta The abdominal aorta is the largest artery in the abdominal cavity. As part of the aorta, it ...

celiac artery
,
superior mesenteric artery In human anatomy The human body is the structure of a human being Humans (''Homo sapiens'') are the most abundant and widespread species In biology, a species is the basic unit of biological classification, classification and ...
, and
inferior mesenteric artery In human anatomy The human body is the structure of a human being Humans (''Homo sapiens'') are the most abundant and widespread species In biology, a species is the basic unit of biological classification, classification and a ...
. The areas supplied by these arteries are used to define the
midgut The midgut is the portion of the embryo An embryo is the early stage of development of a multicellular organism A multicellular organism is an organism that consists of more than one cell (biology), cell, in contrast to a unicellular organism ...
,
hindgut The hindgut (or epigaster) is the Posterior (anatomy), posterior (Caudal (anatomical term), caudal) part of the alimentary canal. In mammals, it includes the Anatomical terms of location#Proximal and distal, distal third of the transverse colon and ...
and
foregut The foregut is the anterior part of the alimentary canal, from the mouth to the duodenum at the entrance of the bile duct. Beyond the stomach, the foregut is attached to the abdominal walls by mesentery. The foregut arises from the endoderm, develo ...
. The surrounded sac becomes the primitive gut. Sections of this gut begin to differentiate into the organs of the gastrointestinal tract, such as the esophagus,
stomach The stomach is a muscular, in the of humans and many other animals, including several s. The stomach has a dilated structure and functions as a vital organ. In the digestive system the stomach is involved in the second phase of digestion, ...

stomach
, and
intestine The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system The human digestive system consists of the gastrointestinal tract The gastrointestinal tract, (GI tract, GIT, d ...

intestine
s. The esophagus develops as part of the foregut tube. The innervation of the esophagus develops from the
pharyngeal arch The pharyngeal arches, also known as visceral arches'','' are structures seen in the embryonic development An embryo is the early stage of development of a multicellular organism A multicellular organism is an organism that consists of mor ...
es.


Function


Swallowing

Food is
ingested Ingestion is the consumption of a substance by an organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individual contiguous system that embodies the Life#Biology, properties of life. I ...
through the
mouth In animal anatomy Anatomy (Greek ''anatomē'', 'dissection') is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science which deals with the structural organization ...

mouth
and when
swallowed Swallowing, sometimes called deglutition in scientific contexts, is the process in the human or animal body that allows for a substance to pass from the mouth In animal anatomy Anatomy (Greek ''anatomē'', 'dissection') is the branch of b ...
passes first into the
pharynx The pharynx (plural: pharynges) is the part of the throat behind the human mouth, mouth and nasal cavity, and above the esophagus and trachea – the tubes going down to the stomach and the lungs. It is found in vertebrates and invertebrates, thou ...

pharynx
and then into the esophagus. The esophagus is thus one of the first components of the
digestive system The human digestive system consists of the human gastrointestinal tract, gastrointestinal tract plus the accessory organs of digestion (the tongue, salivary glands, pancreas, liver, and gallbladder). Digestion involves the breakdown of food in ...
and the
gastrointestinal tract The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system The human digestive system consists of the gastrointestinal tract The gastrointestinal tract, (GI tract, GIT, d ...
. After food passes through the esophagus, it enters the stomach. When food is being swallowed, the
epiglottis The epiglottis is a leaf-shaped flap in the throat In vertebrate anatomy, the throat is the front part of the neck, internally positioned in front of the vertebra, vertebrae. It contains the Human pharynx, pharynx and larynx. An important secti ...

epiglottis
moves backward to cover the
larynx The larynx (), commonly called the voice box, is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exist ...

larynx
, preventing food from entering the
trachea The trachea, also known as the windpipe, is a cartilaginous Cartilage (cartilaginous tissue) is a resilient and smooth elastic tissue, rubber-like padding that covers and protects the ends of long bone A bone is a Stiffness, rigid tissue ...

trachea
. At the same time, the upper esophageal sphincter relaxes, allowing a bolus of
food Food is any substance consumed to provide Nutrient, nutritional support for an organism. Food is usually of plant, animal or Fungus, fungal origin, and contains essential nutrients, such as carbohydrates, fats, protein (nutrient), proteins, vi ...

food
to enter.
Peristaltic Peristalsis is a radially symmetrical Symmetry in biology refers to the symmetry observed in organisms, including plants, animals, fungi, and bacteria. External symmetry can be easily seen by just looking at an organism. For example, take ...

Peristaltic
contractions of the esophageal muscle push the food down the esophagus. These rhythmic contractions occur both as a reflex response to food that is in the mouth, and also as a response to the sensation of food within the esophagus itself. Along with peristalsis, the lower esophageal sphincter relaxes.


Reducing gastric reflux

The stomach produces
gastric acid Gastric acid, gastric juice, or stomach acid, is a digestive fluid formed within the stomach lining. With a pH between 1 and 3, gastric acid An acid is a or capable of donating a (hydrogen ion H+) (a ), or, alternatively, capable of for ...
, a strongly
acid An acid is a or capable of donating a (hydrogen ion H+) (a ), or, alternatively, capable of forming a with an (a ). The first category of acids are the proton donors, or s. In the special case of , proton donors form the H3O+ and are ...
ic mixture consisting of
hydrochloric acid Hydrochloric acid +(aq) Cl−(aq) or H3O+ Cl− also known as muriatic acid, is an aqueous solution An aqueous solution is a solution Solution may refer to: * Solution (chemistry) Image:SaltInWaterSolutionLiquid.jpg, upMaking a salin ...

hydrochloric acid
(HCl) and
potassium Potassium is a chemical element In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, b ...

potassium
and
sodium Sodium is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical eleme ...
salts to enable food
digestion Digestion is the breakdown of large insoluble food Food is any substance consumed to provide Nutrient, nutritional support for an organism. Food is usually of plant, animal or Fungus, fungal origin, and contains essential nutrients, such a ...
. Constriction of the upper and lower esophageal sphincters helps to prevent reflux (backflow) of gastric contents and acid into the esophagus, protecting the esophageal mucosa. The acute
angle of His The angle of His, also known as the esophagogastric angle, is the acute angle created between the cardia at the entrance to the stomach, and the esophagus. It helps to prevent acid reflux of stomach acid into the esophagus. It is commonly undevelop ...
and the lower crura of the diaphragm also help this sphincteric action.


Gene and protein expression

About 20,000 protein-coding genes are expressed in human cells and nearly 70% of these genes are expressed in the normal esophagus. Some 250 of these genes are more specifically expressed in the esophagus with less than 50 genes being highly specific. The corresponding esophagus-specific proteins are mainly involved in squamous differentiation such as
keratin Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. Alpha-keratin Alpha-keratin, or α-keratin, is a type of keratin Keratin () is one of a family of fibrous structural proteins known as Scleroprot ...

keratin
s KRT13, KRT4 and KRT6C. Other specific proteins that help lubricate the inner surface of esophagus are
mucin Mucins () are a family of high molecular weight A scanning tunneling microscopy image of pentacene molecules, which consist of linear chains of five carbon rings. A molecule is an electrically Electricity is the set of physical ph ...

mucin
s such as
MUC21 Mucin 21, cell surface associated is a protein that in humans is encoded by the MUC21 gene. References Further reading

{{gene-6-stub Mucins ...
and MUC22. Many genes with elevated expression are also shared with skin and other organs that are composed of squamous epithelia.


Clinical significance

The main conditions affecting the esophagus are described here. For a more complete list, see
esophageal disease Esophageal diseases can derive from congenital conditions, or they can be acquired later in life. Many people experience a burning sensation in their chest occasionally, caused by stomach acids refluxing into the esophagus The esophagus (Ame ...
.


Inflammation

Inflammation of the esophagus is known as
esophagitis Esophagitis, also spelled oesophagitis, is a disease characterized by inflammation of the esophagus The esophagus (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, ...
.
Reflux Reflux is a technique involving the condensation Condensation is the change of the state of matter In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (phy ...

Reflux
of
gastric acid Gastric acid, gastric juice, or stomach acid, is a digestive fluid formed within the stomach lining. With a pH between 1 and 3, gastric acid An acid is a or capable of donating a (hydrogen ion H+) (a ), or, alternatively, capable of for ...
s from the stomach, infection, substances ingested (for example, corrosives), some
medications A medication (also called medicament, medicine, pharmaceutical drug, medicinal drug or simply drug) is a drug Uncoated tablets, consisting of about 90% acetylsalicylic acid, along with a minor amount of inert fillers and binders. Aspir ...
(such as
bisphosphonate Bisphosphonates are a class of drugs that prevent the loss of bone density A scanner used to measure bone density using dual energy X-ray absorptiometry Bone density, or bone mineral density (BMD), is the amount of bone mineral in bone tissue. ...
s), and
food allergies A food allergy is an abnormal immune response An immune response is a reaction which occurs within an organism for the purpose of defending against foreign invaders. These invaders include a wide variety of different microorganisms including vi ...
can all lead to esophagitis.
Esophageal candidiasis Esophageal candidiasis is an opportunistic infection An opportunistic infection is an infection An infection is the invasion of an organism's body Tissue (biology), tissues by Pathogen, disease-causing agents, their multiplication, and the reac ...
is an infection of the yeast ''
Candida albicans ''Candida albicans'' is an opportunistic pathogenic yeast Yeasts are eukaryotic Eukaryotes () are organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individual contiguous ...

Candida albicans
'' that may occur when a person is
immunocompromised Immunodeficiency, also known as immunocompromisation, is a state in which the immune system The immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of pathoge ...
. the causes of some forms of esophagitis, such as
eosinophilic esophagitis Eosinophilic esophagitis (EoE) is an allergic Allergies, also known as allergic diseases, are a number of conditions caused by hypersensitivity Hypersensitivity (also called hypersensitivity reaction or intolerance) refers to undesirable ...
, are not well-characterized, but may include
Th2 The T helper cells (Th cells), also known as CD4+ cells or CD4-positive cells, are a type of that play an important role in the , particularly in the . As their name suggests, they "help" the activity of other immune cells by releasing , small ...
-mediated atopies or genetic factors. There appear to be correlations between eosinophilic esophagitis,
asthma Asthma is a long-term Long-Term Capital Management L.P. (LTCM) was a hedge fund''A financial History of the United States Volume II: 1970–2001'', Jerry W. Markham, Chapter 5: "Bank Consolidation", M. E. Sharpe, Inc., 2002 based in Greenwich, ...

asthma
(itself with an
eosinophilic Eosinophilic (Greek suffix -phil- A philia is the love or Fixation (psychology), obsession with a particular thing or subject. The suffix -philia is used to specify the love or obsession with something more specific. It is antonymic to -phobia. ...
component),
eczema Dermatitis is inflammation of the Human skin, skin, typically characterized by itchiness, erythema, redness and a rash. In cases of short duration, there may be small blisters, while in long-term cases the skin may become lichenification, thick ...

eczema
, and allergic
rhinitis Rhinitis, also known as coryza, is irritation and inflammation of the mucous membrane inside the nose A nose is a protuberance in vertebrate Vertebrates () comprise all species of animal Animals (also called Metazoa) are multic ...
, though it is not clear whether these conditions contribute to eosinophilic esophagitis or vice versa, or if they are symptoms of mutual underlying factors. Esophagitis can cause painful swallowing and is usually treated by managing the cause of the esophagitis - such as managing reflux or treating infection.


Barrett's esophagus

Prolonged esophagitis, particularly from gastric reflux, is one factor thought to play a role in the development of
Barrett's esophagus Barrett's esophagus is a condition in which there is an abnormal (metaplastic) change in the mucosal cells lining the lower portion of the esophagus, from normal stratified squamous epithelium to simple columnar epithelium with interspersed goblet ...
. In this condition, there is
metaplasia Metaplasia ( gr, "change in form") is the transformation of one differentiated cell type A cell type is a classification used to distinguish between morphologically or phenotypically distinct cell forms within a species In biology, a ...
of the lining of the lower esophagus, which changes from stratified squamous epithelia to
simple columnar epithelia A simple columnar epithelium is a single layer of columnar cells attached to the basement membrane, with oval-shaped nuclei located in the basal region. In humans, a simple columnar epithelium lines most organs of the digestive tract The gast ...
. Barrett's esophagus is thought to be one of the main contributors to the development of
esophageal cancer Esophageal cancer is cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumor A benign tumor is a mass of cells Cell most ...
.


Cancer

There are two main types of cancer of the esophagus.
Squamous cell carcinoma Squamous cell carcinomas (SCCs), also known as epidermoid carcinomas, comprise a number of different types of cancer that result from Epithelium#Cell types, squamous cells. These cells form on the surface of the skin, on the lining of hollow organ ...

Squamous cell carcinoma
is a
carcinoma Carcinoma is a malignancy that develops from epithelial cells Epithelium () is one of the four basic types of animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biology), biological k ...
that can occur in the squamous cells lining the esophagus. This type is much more common in
China China (), officially the People's Republic of China (PRC; ), is a country in East Asia East Asia is the eastern region of Asia Asia () is Earth's largest and most populous continent, located primarily in the Eastern Hemisphere ...

China
and
Iran Iran ( fa, ایران ), also called Persia, and officially the Islamic Republic of Iran, is a country in Western Asia Western Asia, West Asia, or Southwest Asia, is the westernmost subregion A subregion is a part of a larger regio ...

Iran
. The other main type is an
adenocarcinoma Adenocarcinoma (; plural adenocarcinomas or adenocarcinomata ) (AC) is a type of cancerous Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with ...

adenocarcinoma
that occurs in the glands or columnar tissue of the esophagus. This is most common in
developed countries A developed country (or industrialized country, high-income country, more economically developed country (MEDC), advanced country) is a sovereign state A sovereign state is a political entity A polity is an identifiable political entity ...
in those with Barrett's esophagus, and occurs in the cuboidal cells. In its early stages, esophageal cancer may not have any symptoms at all. When severe, esophageal cancer may eventually cause obstruction of the esophagus, making swallowing of any solid foods very difficult and causing weight loss. The progress of the cancer is staged using a system that measures how far into the esophageal wall the cancer has invaded, how many
lymph node A lymph node, or lymph gland, is a kidney The kidneys are two reddish-brown bean-shaped organs An organ is a group of tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A giv ...

lymph node
s are affected, and whether there are any
metastases Metastasis is a pathogenic agent's spread from an initial or primary site to a different or secondary site within the host's body; the term is typically used when referring to metastasis by a cancerous tumor. The newly pathological sites, then, ...
in different parts of the body. Esophageal cancer is often managed with radiotherapy, chemotherapy, and may also be managed by partial surgical removal of the esophagus. Inserting a
stent In medicine Medicine is the science Science () is a systematic enterprise that builds and organizes knowledge Knowledge is a familiarity, awareness, or understanding of someone or something, such as facts ( descriptive knowledge) ...
into the esophagus, or inserting a
nasogastric tube Nasogastric intubation is a medical process involving the insertion of a plastic tube (nasogastric tube or NG tube) through the nose A nose is a protuberance in vertebrate Vertebrates () comprise all species of animal Animals ( ...
, may also be used to ensure that a person is able to digest enough food and water. , the prognosis for esophageal cancer is still poor, so palliative therapy may also be a focus of treatment.


Varices

Esophageal varices Esophageal varices are extremely dilated sub-mucosal vein Veins are blood vessels The blood vessels are the components of the circulatory system The circulatory system, also called the cardiovascular system or the vascular system, is an ...
are swollen twisted branches of the
azygous vein The azygos vein is a vein running up the right side of the thoracic vertebral column draining itself towards the superior vena cava. It connects the systems of superior vena cava and inferior vena cava and can provide an alternative path for blood ...
in the lower third of the esophagus. These blood vessels
anastomose An anastomosis (plural anastomoses) is a connection or opening between two things (especially cavities or passages) that are normally diverging or branching, such as between blood vessels, leaf veins, or streams. Such a connection may be normal ...
(join up) with those of the
portal vein The portal vein or hepatic portal vein (HPV) is a blood vessel The blood vessels are the components of the circulatory system The circulatory system, also called the cardiovascular system or the vascular system, is an organ system that ...
when
portal hypertension Portal hypertension is abnormally increased portal venous pressure – blood pressure in the portal vein The portal vein or hepatic portal vein (HPV) is a blood vessel The blood vessels are the components of the circulatory system Th ...
develops. These blood vessels are engorged more than normal, and in the worst cases may partially obstruct the esophagus. These blood vessels develop as part of a collateral circulation that occurs to drain blood from the
abdomen The abdomen (colloquially called the belly, tummy, midriff or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the Trunk (anatomy) ...

abdomen
as a result of
portal hypertension Portal hypertension is abnormally increased portal venous pressure – blood pressure in the portal vein The portal vein or hepatic portal vein (HPV) is a blood vessel The blood vessels are the components of the circulatory system Th ...
, usually as a result of
liver disease Liver disease (also called hepatic disease) is a type of damage to or disease A disease is a particular abnormal condition that negatively affects the structure A structure is an arrangement and organization of interrelated elements i ...
s such as
cirrhosis Cirrhosis, also known as liver cirrhosis or hepatic cirrhosis, and end-stage liver disease, is the impaired liver function caused by the formation of scar tissue known as fibrosis Fibrosis, also known as fibrotic scarring, is a pathological wo ...
. This collateral circulation occurs because the lower part of the esophagus drains into the left gastric vein, which is a branch of the portal vein. Because of the extensive venous plexus that exists between this vein and other veins, if portal hypertension occurs, the direction of blood drainage in this vein may reverse, with blood draining from the portal venous system, through the plexus. Veins in the plexus may engorge and lead to varices. Esophageal varices often do not have symptoms until they rupture. A ruptured varix is considered a medical emergency because varices can bleed a lot. A bleeding varix may cause a person to vomit blood, or suffer shock. To deal with a ruptured varix, a band may be placed around the bleeding blood vessel, or a small amount of a clotting agent may be injected near the bleed. A surgeon may also try to use a small inflatable balloon to apply pressure to stop the wound.
IV fluids Intravenous therapy (abbreviated as IV therapy) is a medical technique that delivers fluids, medications and nutrition directly into a person's vein. The intravenous route of administration is commonly used for rehydration or to provide nutrition ...
and
blood product A blood product is any therapeutic substance prepared from human blood Blood is a body fluid Body fluids, bodily fluids, or biofluids are liquid A liquid is a nearly incompressible In fluid mechanics or more generally continuum me ...
s may be given in order to prevent
hypovolemia Hypovolemia, also known as volume depletion or volume contraction, is a state of abnormally low extracellular fluid in the body. This may be due to either a loss of both salt and water or a decrease in blood volume. Hypovolemia refers to the loss ...
from excess blood loss.


Motility disorders

Several disorders affect the motility of food as it travels down the esophagus. This can cause difficult swallowing, called
dysphagia Dysphagia is difficulty in swallowing Swallowing, sometimes called deglutition in scientific contexts, is the process in the human or animal body that allows for a substance to pass from the mouth, to the pharynx, and into the esophagus, while ...
, or painful swallowing, called
odynophagia Odynophagia is pain when swallowing. The pain may be felt in the mouth or throat and can occur with or without difficulty swallowing. The pain may be described as an ache, burning sensation, or occasionally a stabbing pain that radiates to the b ...
. Achalasia refers to a failure of the lower esophageal sphincter to relax properly, and generally develops later in life. This leads to progressive enlargement of the esophagus, and possibly eventual megaesophagus. A nutcracker esophagus refers to swallowing that can be extremely painful. Diffuse esophageal spasm is a spasm of the esophagus that can be one cause of chest pain. Such referred pain to the wall of the upper chest is quite common in esophageal conditions. Sclerosis of the esophagus, such as with systemic sclerosis or in CREST syndrome may cause hardening of the walls of the esophagus and interfere with peristalsis.


Malformations

Esophageal strictures are usually benign and typically develop after a person has had GERD, reflux for many years. Other strictures may include esophageal webs (which can also be congenital) and damage to the esophagus by radiotherapy, corrosive ingestion, or eosinophilic esophagitis. A Schatzki ring is fibrosis at the gastro-esophageal junction. Strictures may also develop in chronic anemia, and Plummer-Vinson syndrome. Two of the most common congenital disorder, congenital malformations affecting the esophagus are an esophageal atresia where the esophagus ends in a blind sac instead of connecting to the stomach; and an tracheoesophageal fistula, esophageal fistula – an abnormal connection between the esophagus and the trachea. Both of these conditions usually occur together. These are found in about 1 in 3500 births. Half of these cases may be part of a syndrome where other abnormalities are also present, particularly of the
heart The heart is a muscular MUSCULAR (DS-200B), located in the United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain,Usage is mixed. The Guardian' and Telegraph' use ...

heart
or limb (anatomy), limbs. The other cases occur singly.


Imaging

An X-ray of Barium swallow, swallowed barium may be used to reveal the size and shape of the esophagus, and the presence of any masses. The esophagus may also be medical imaging, imaged using a flexible camera inserted into the esophagus, in a procedure called an
endoscopy An endoscopy (''looking inside'') is a procedure used in medicine Medicine is the science Science () is a systematic enterprise that builds and organizes knowledge Knowledge is a familiarity, awareness, or understanding of someon ...

endoscopy
. If an endoscopy is used on the stomach, the camera will also have to pass through the esophagus. During an endoscopy, a biopsy may be taken. If cancer of the esophagus is being investigated, other methods, including a
CT scan A CT scan or computed tomography scan (formerly known as computed axial tomography or CAT scan) is a medical image, imaging Scientific technique, technique used in radiology to obtain detailed internal images of the body noninvasively for Diagno ...

CT scan
, may also be used.


History

The word ''esophagus'' (
British English British English (BrE) is the standard dialect A standard language (also standard variety, standard dialect, and standard) is a language variety that has undergone substantial codification of grammar and usage and is employed by a populatio ...
: ''oesophagus''), comes from the el, οἰσοφάγος () meaning ''gullet''. It derives from List of Greek and Latin roots in English#Oesophag-, two roots ''(eosin)'' to carry and () to eat. The use of the word oesophagus, has been documented in anatomical literature since at least the time of Hippocrates, who noted that "the oesophagus ... receives the greatest amount of what we consume." Its existence in other animals and its relationship with the
stomach The stomach is a muscular, in the of humans and many other animals, including several s. The stomach has a dilated structure and functions as a vital organ. In the digestive system the stomach is involved in the second phase of digestion, ...

stomach
was documented by the Roman Empire, Roman naturalist Pliny the Elder (AD23–AD79), and the peristalsis, peristaltic contractions of the esophagus have been documented since at least the time of Galen. The first attempt at surgery on the esophagus focused in the neck, and was conducted in dogs by Theodore Billroth in 1871. In 1877 Czerny carried out surgery in people. By 1908, an operation had been performed by Voeckler to remove the esophagus, and in 1933 the first surgical removal of parts of the lower esophagus, (to control
esophageal cancer Esophageal cancer is cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumor A benign tumor is a mass of cells Cell most ...
), had been conducted. The Nissen fundoplication, in which the stomach is wrapped around the lower esophageal sphincter to stimulate its function and control GERD, reflux, was first conducted by Rudolph Nissen in 1955.


Other animals


Vertebrates

In tetrapods, the pharynx is much shorter, and the esophagus correspondingly longer, than in fish. In the majority of vertebrates, the esophagus is simply a connecting tube, but in some Bird anatomy, birds, which regurgitate components to feed their young, it is extended towards the lower end to form a crop (anatomy), crop for storing food before it enters the true stomach. In ruminants, animals with four stomachs, a groove called the ''sulcus reticuli'' is often found in the esophagus, allowing milk to drain directly into the hind stomach, the abomasum. In the horse the esophagus is about in length, and carries food to the stomach. A muscular ring, called the cardiac sphincter, connects the stomach to the esophagus. This sphincter is very well developed in horses. This and the oblique angle at which the esophagus connects to the stomach explains why horses cannot vomiting, vomit. The esophagus is also the area of the digestive tract where horses may suffer from the condition known as choke (horse), choke. The esophagus of snakes is remarkable for the distension it undergoes when swallowing prey. In most fish, the esophagus is extremely short, primarily due to the length of the pharynx (which is associated with the gills). However, some fish, including lampreys, chimaeras, and lungfish, have no true stomach, so that the esophagus effectively runs from the pharynx directly to the
intestine The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system The human digestive system consists of the gastrointestinal tract The gastrointestinal tract, (GI tract, GIT, d ...

intestine
, and is therefore somewhat longer. In many vertebrates, the esophagus is lined by
stratified squamous epithelium A stratified squamous epithelium consists of squamous (flattened) epithelial cell Epithelium is one of the four basic types of animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biolo ...

stratified squamous epithelium
without glands. In fish, the esophagus is often lined with columnar epithelium, and in amphibians, sharks and ray (fish), rays, the esophageal epithelium is ciliated, helping to wash food along, in addition to the action of muscular peristalsis. In addition, in the bat ''Plecotus auritus'', fish and some amphibians, glands secreting pepsinogen or
hydrochloric acid Hydrochloric acid +(aq) Cl−(aq) or H3O+ Cl− also known as muriatic acid, is an aqueous solution An aqueous solution is a solution Solution may refer to: * Solution (chemistry) Image:SaltInWaterSolutionLiquid.jpg, upMaking a salin ...

hydrochloric acid
have been found. The muscle of the esophagus in many mammals is initially striated but then becomes smooth muscle in the caudal third or so. In canidae, canines and ruminants, however, it is entirely striated to allow regurgitation to feed young (canines) or regurgitation to chew cud (ruminants). It is entirely smooth muscle in amphibians, reptiles and birds. Contrary to popular belief, an adult human body would not be able to pass through the esophagus of a whale, which generally measures less than in diameter, although in larger baleen whales it may be up to when fully distended.


Invertebrates

A structure with the same name is often found in invertebrates, including molluscs and arthropods, connecting the oral cavity with the stomach. In terms of the Digestive system of gastropods, digestive system of snails and slugs, the mouth opens into an esophagus, which connects to the stomach. Because of Torsion (gastropod), torsion, which is the rotation of the main body of the animal during larval development, the esophagus usually passes around the stomach, and opens into its back, furthest from the mouth. In species that have undergone de-torsion, however, the esophagus may open into the anterior of the stomach, which is the reverse of the usual gastropod arrangement. There is an extensive rostrum (anatomy), rostrum at the front of the esophagus in all carnivorous snails and slugs. In the freshwater snail species ''Tarebia granifera'', the brood pouch is above the esophagus.Appleton C. C., Forbes A. T.& Demetriades N. T. (2009)
"The occurrence, bionomics and potential impacts of the invasive freshwater snail ''Tarebia granifera'' (Lamarck, 1822) (Gastropoda: Thiaridae) in South Africa"
. ''Zoologische Mededelingen'' 83.
In the cephalopods, the brain often surrounds the esophagus.


See also


References


External links

{{Authority control Digestive system Thorax (human anatomy) Organs (anatomy) Human head and neck Abdomen