The mediastinum (from ) is the central compartment of the
thoracic cavity
The thoracic cavity (or chest cavity) is the chamber of the body of vertebrates that is protected by the thoracic wall (rib cage and associated skin, muscle, and fascia). The central compartment of the thoracic cavity is the mediastinum. There ...
. Surrounded by
loose connective tissue
Loose connective tissue, sometimes called areolar tissue, is a cellular connective tissue with thin and relatively sparse collagen fibers. Its ground substance occupies more volume than the fibers do. It has a viscous to gel-like consistenc ...
, it is an undelineated region that contains a group of structures within the
thorax
The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the cre ...
, namely the
heart
The heart is a muscular organ in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide t ...
and its vessels, the
esophagus
The esophagus (American English) or oesophagus (British English; both ), non-technically known also as the food pipe or gullet, is an organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to the ...
, the
trachea
The trachea, also known as the windpipe, is a Cartilage, cartilaginous tube that connects the larynx to the bronchi of the lungs, allowing the passage of air, and so is present in almost all air-breathing animals with lungs. The trachea extends ...
, the
phrenic
The phrenic nerve is a mixed motor/sensory nerve which originates from the C3-C5 spinal nerves in the neck. The nerve is important for breathing because it provides exclusive motor control of the diaphragm, the primary muscle of respiration. ...
and
cardiac nerves, the
thoracic duct
In human anatomy, the thoracic duct is the larger of the two lymph ducts of the lymphatic system. It is also known as the ''left lymphatic duct'', ''alimentary duct'', ''chyliferous duct'', and ''Van Hoorne's canal''. The other duct is the right ...
, the
thymus
The thymus is a specialized primary lymphoid organ of the immune system. Within the thymus, thymus cell lymphocytes or ''T cells'' mature. T cells are critical to the adaptive immune system, where the body adapts to specific foreign invaders. ...
and the
lymph nodes
A lymph node, or lymph gland, is a kidney-shaped organ of the lymphatic system and the adaptive immune system. A large number of lymph nodes are linked throughout the body by the lymphatic vessels. They are major sites of lymphocytes that includ ...
of the central chest.
Anatomy
![CT-Thorax-5](https://upload.wikimedia.org/wikipedia/commons/e/ec/CT-Thorax-5.0-B31f-HD.ogg)
The mediastinum lies within the
thorax
The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the cre ...
and is enclosed on the right and left by
pleurae
The pulmonary pleurae (''sing.'' pleura) are the two opposing layers of serous membrane overlying the lungs and the inside of the surrounding chest walls.
The inner pleura, called the visceral pleura, covers the surface of each lung and dips be ...
. It is surrounded by the chest wall in front, the
lung
The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of t ...
s to the sides and the
spine at the back. It extends from the
sternum
The sternum or breastbone is a long flat bone located in the central part of the chest. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, lungs, and major blood vessels from injury. Sh ...
in front to the
vertebral column
The vertebral column, also known as the backbone or spine, is part of the axial skeleton. The vertebral column is the defining characteristic of a vertebrate in which the notochord (a flexible rod of uniform composition) found in all chordata, ...
behind.
It contains all the organs of the thorax except the lungs.
It is continuous with the loose connective tissue of the
neck
The neck is the part of the body on many vertebrates that connects the head with the torso. The neck supports the weight of the head and protects the nerves that carry sensory and motor information from the brain down to the rest of the body. In ...
.
![Mediastinum](https://upload.wikimedia.org/wikipedia/commons/a/ab/Mediastinum.png)
The mediastinum can be divided into an upper (or superior) and lower (or inferior) part:
* The superior mediastinum starts at the
superior thoracic aperture
The superior thoracic aperture, also known as the thoracic outlet, or thoracic inlet refers to the opening at the top of the thoracic cavity. It is also clinically referred to as the thoracic outlet, in the case of thoracic outlet syndrome. A low ...
and ends at the
thoracic plane
The mediastinum (from ) is the central compartment of the thoracic cavity. Surrounded by loose connective tissue, it is an undelineated region that contains a group of structures within the thorax, namely the heart and its vessels, the esophagu ...
.
* The inferior mediastinum from this level to the
diaphragm. This lower part is subdivided into three regions, all relative to the
pericardium
The pericardium, also called pericardial sac, is a double-walled sac containing the heart and the roots of the great vessels. It has two layers, an outer layer made of strong connective tissue (fibrous pericardium), and an inner layer made of ...
– the anterior mediastinum being in front of the pericardium, the ''middle mediastinum'' contains the pericardium and its contents, and the ''posterior mediastinum'' being behind the pericardium.
Anatomist
Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having its ...
s,
surgeon
In modern medicine, a surgeon is a medical professional who performs surgery. Although there are different traditions in different times and places, a modern surgeon usually is also a licensed physician or received the same medical training as ...
s, and clinical
radiologists
Radiology ( ) is the medical discipline that uses medical imaging to diagnose diseases and guide their treatment, within the bodies of humans and other animals. It began with radiography (which is why its name has a root referring to radiatio ...
compartmentalize the mediastinum differently. For instance, in the radiological scheme of Felson, there are only three compartments (anterior, middle, and posterior), and the heart is part of the middle (inferior) mediastinum.
Thoracic plane
The transverse thoracic plane, thoracic plane, plane of Louis or plane of Ludwig is an important
anatomical plane
An anatomical plane is a hypothetical plane used to transect the body, in order to describe the location of structures or the direction of movements. In human and animal anatomy, three principal planes are used:
* The sagittal plane or lateral ...
at the level of the
sternal angle
The sternal angle (also known as the angle of Louis, angle of Ludovic or manubriosternal junction) is the synarthrotic joint formed by the articulation of the manubrium and the body of the sternum.
The sternal angle is a palpable clinical landma ...
and the
T4/T5 intervertebral disc
An intervertebral disc (or intervertebral fibrocartilage) lies between adjacent vertebrae in the vertebral column. Each disc forms a fibrocartilaginous joint (a symphysis), to allow slight movement of the vertebrae, to act as a ligament to hold t ...
.
It serves as an imaginary boundary that separates the superior and inferior mediastinum.
[Thoracic Wall, Pleura, and Pericardium – Dissector Answers](_blank)
A number of important anatomical structures and transitions occur at the level of the thoracic plane, including:
* The
carina
Carina may refer to:
Places
Australia
* Carina, Queensland, a suburb in Brisbane
* Carina Heights, Queensland, a suburb in Brisbane
* Carina, Victoria, a locality in Mildura
Serbia
* Carina, Osečina, a village in the Kolubara District
...
l bifurcation of the
trachea
The trachea, also known as the windpipe, is a Cartilage, cartilaginous tube that connects the larynx to the bronchi of the lungs, allowing the passage of air, and so is present in almost all air-breathing animals with lungs. The trachea extends ...
into the left and right main
bronchi
A bronchus is a passage or airway in the lower respiratory tract that conducts air into the lungs. The first or primary bronchi pronounced (BRAN-KAI) to branch from the trachea at the carina are the right main bronchus and the left main bronchus. ...
.
* The
left recurrent laryngeal nerve
The recurrent laryngeal nerve (RLN) is a branch of the vagus nerve (cranial nerve X) that supplies all the intrinsic muscles of the larynx, with the exception of the cricothyroid muscles. There are two recurrent laryngeal nerves, right and lef ...
branching off the left
vagus nerve
The vagus nerve, also known as the tenth cranial nerve, cranial nerve X, or simply CN X, is a cranial nerve that interfaces with the parasympathetic control of the heart, lungs, and digestive tract. It comprises two nerves—the left and right ...
and hooking under the
ligamentum arteriosum
The ligamentum arteriosum (arterial ligament), also known as the Ligament of Botallo or Harvey's ligament, is a small ligament attaching the aorta to the pulmonary artery. It serves no function in adults but is the remnant of the ductus arteriosus ...
between the
aortic arch
The aortic arch, arch of the aorta, or transverse aortic arch () is the part of the aorta between the ascending and descending aorta. The arch travels backward, so that it ultimately runs to the left of the trachea.
Structure
The aorta begins a ...
above and the
pulmonary trunk
A pulmonary artery is an artery in the pulmonary circulation that carries deoxygenated blood from the right side of the heart to the lungs. The largest pulmonary artery is the ''main pulmonary artery'' or ''pulmonary trunk'' from the heart, and t ...
below.
* The starting of the
cardiac plexus
The cardiac plexus is a plexus of nerves situated at the base of the heart that innervates the heart.
Structure
The cardiac plexus is divided into a superficial part, which lies in the concavity of the aortic arch, and a deep part, between the ao ...
.
* The
azygos 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 ...
arching over the right main bronchus and joining into the
superior vena cava
The superior vena cava (SVC) is the superior of the two venae cavae, the great venous trunks that return deoxygenated blood from the systemic circulation to the right atrium of the heart. It is a large-diameter (24 mm) short length vein th ...
.
* The
thoracic duct
In human anatomy, the thoracic duct is the larger of the two lymph ducts of the lymphatic system. It is also known as the ''left lymphatic duct'', ''alimentary duct'', ''chyliferous duct'', and ''Van Hoorne's canal''. The other duct is the right ...
crossing the midline from right to left behind the
esophagus
The esophagus (American English) or oesophagus (British English; both ), non-technically known also as the food pipe or gullet, is an organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to the ...
* The end of the
pretracheal and
prevertebral fascia
The prevertebral fascia (or prevertebral layer of cervical fascia) is a fascia in the neck.
Variations
In some literature, the prevertebral fascia also includes the other fascial layers extending around the vertebral column and enclosing all musc ...
e.
Superior
The superior mediastinum is bounded:
* ''superiorly'' by the
thoracic inlet
The superior thoracic aperture, also known as the thoracic outlet, or thoracic inlet refers to the opening at the top of the thoracic cavity. It is also clinically referred to as the thoracic outlet, in the case of thoracic outlet syndrome. A low ...
, the upper opening of the
thorax
The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the cre ...
;
* ''inferiorly'' by the transverse thoracic plane. which is an imaginary plane passing from the sternal angle anteriorly to the lower border of the body of the 4th thoracic vertebra posteriorly;
* ''laterally'' by the
pleurae
The pulmonary pleurae (''sing.'' pleura) are the two opposing layers of serous membrane overlying the lungs and the inside of the surrounding chest walls.
The inner pleura, called the visceral pleura, covers the surface of each lung and dips be ...
;
* ''anteriorly'' by the
manubrium
The sternum or breastbone is a long flat bone located in the central part of the chest. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, lungs, and major blood vessels from injury. Sha ...
of the sternum;
* ''posteriorly'' by the first four thoracic
vertebral bodies
The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic ...
.
![Mediastinal structures on chest X-ray, annotated](https://upload.wikimedia.org/wikipedia/commons/8/89/Mediastinal_structures_on_chest_X-ray%2C_annotated.jpg)
;Contents
* muscles
** origins of the
Sternohyoidei and
Sternothyreoidei
The sternothyroid muscle, or sternothyroideus, is an Infrahyoid muscles, infrahyoid muscle in the neck. It acts to depress the hyoid bone. It is below the sternohyoid muscle. It is shorter and wider than the sternohyoid.
Structure
The sternothyr ...
** lower ends of the
Longi colli
The longus colli muscle (Latin for ''long muscle of the neck'') is a muscle of the human body.
The longus colli is situated on the anterior surface of the vertebral column, between the atlas and the third thoracic vertebra.
It is broad in the mid ...
* arteries
**
aortic arch
The aortic arch, arch of the aorta, or transverse aortic arch () is the part of the aorta between the ascending and descending aorta. The arch travels backward, so that it ultimately runs to the left of the trachea.
Structure
The aorta begins a ...
**
brachiocephalic artery
The brachiocephalic artery (or brachiocephalic trunk or innominate artery) is an artery of the mediastinum that supplies blood to the right arm and the head and neck.
It is the first branch of the aortic arch. Soon after it emerges, the brachiocep ...
** thoracic portions of the
left common carotid
In anatomy, the left and right common carotid arteries (carotids) (Entry "carotid"
in
left subclavian
In human anatomy, the subclavian arteries are paired major arteries of the upper thorax, below the clavicle. They receive blood from the aortic arch. The left subclavian artery supplies blood to the left arm and the right subclavian artery supplie ...
* veins
**
brachiocephalic veins
The left and right brachiocephalic veins (previously called innominate veins) are major veins in the upper chest, formed by the union of each corresponding internal jugular vein and subclavian vein. This is at the level of the sternoclavicular jo ...
and
** upper half of the
superior vena cava
The superior vena cava (SVC) is the superior of the two venae cavae, the great venous trunks that return deoxygenated blood from the systemic circulation to the right atrium of the heart. It is a large-diameter (24 mm) short length vein th ...
** left
highest intercostal vein
The supreme intercostal vein (highest intercostal vein) is a paired vein that drains the first intercostal space on its corresponding side.
It usually drains into the brachiocephalic vein. Alternatively, it drains into the superior intercostal ...
* nerves
**
vagus nerve
The vagus nerve, also known as the tenth cranial nerve, cranial nerve X, or simply CN X, is a cranial nerve that interfaces with the parasympathetic control of the heart, lungs, and digestive tract. It comprises two nerves—the left and right ...
**
cardiac nerve
** superficial and deep cardiac plexuses
**
phrenic nerve
The phrenic nerve is a mixed motor/sensory nerve which originates from the C3-C5 spinal nerves in the neck. The nerve is important for breathing because it provides exclusive motor control of the diaphragm, the primary muscle of respiration. In ...
** left
recurrent laryngeal nerve
The recurrent laryngeal nerve (RLN) is a branch of the vagus nerve (cranial nerve X) that supplies all the intrinsic muscles of the larynx, with the exception of the cricothyroid muscles. There are two recurrent laryngeal nerves, right and le ...
*
trachea
The trachea, also known as the windpipe, is a Cartilage, cartilaginous tube that connects the larynx to the bronchi of the lungs, allowing the passage of air, and so is present in almost all air-breathing animals with lungs. The trachea extends ...
with paratracheal and tracheobronchial lymph nodes
*
esophagus
The esophagus (American English) or oesophagus (British English; both ), non-technically known also as the food pipe or gullet, is an organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to the ...
*
thoracic duct
In human anatomy, the thoracic duct is the larger of the two lymph ducts of the lymphatic system. It is also known as the ''left lymphatic duct'', ''alimentary duct'', ''chyliferous duct'', and ''Van Hoorne's canal''. The other duct is the right ...
* remains of the
thymus
The thymus is a specialized primary lymphoid organ of the immune system. Within the thymus, thymus cell lymphocytes or ''T cells'' mature. T cells are critical to the adaptive immune system, where the body adapts to specific foreign invaders. ...
* some
lymph glands
A lymph node, or lymph gland, is a kidney-shaped organ of the lymphatic system and the adaptive immune system. A large number of lymph nodes are linked throughout the body by the lymphatic vessels. They are major sites of lymphocytes that include ...
* anterior longitudinal ligament
Inferior
;Anterior mediastinum
Is bounded:
* ''laterally'' by the
pleurae
The pulmonary pleurae (''sing.'' pleura) are the two opposing layers of serous membrane overlying the lungs and the inside of the surrounding chest walls.
The inner pleura, called the visceral pleura, covers the surface of each lung and dips be ...
;
* ''posteriorly'' by the
pericardium
The pericardium, also called pericardial sac, is a double-walled sac containing the heart and the roots of the great vessels. It has two layers, an outer layer made of strong connective tissue (fibrous pericardium), and an inner layer made of ...
;
* ''anteriorly'' by the
sternum
The sternum or breastbone is a long flat bone located in the central part of the chest. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, lungs, and major blood vessels from injury. Sh ...
,
the left
transversus thoracis
The transversus thoracis muscle (), also known as triangularis sterni, lies internal to the thoracic cage, anteriorly. It is usually a thin plane of muscular and tendinous fibers, however on athletic individuals it can be a thick 'slab of meat', ...
and the fifth, sixth, and seventh left
costal cartilages
The costal cartilages are bars of hyaline cartilage that serve to prolong the ribs forward and contribute to the elasticity of the walls of the thorax. Costal cartilage is only found at the anterior ends of the ribs, providing medial extension.
...
.
;Contents
* A quantity of
loose areolar tissue
Loose connective tissue, sometimes called areolar tissue, is a cellular connective tissue with thin and relatively sparse collagen fibers. Its ground substance occupies more volume than the fibers do. It has a viscous to gel-like consistenc ...
* Some
lymphatic vessels
The lymphatic vessels (or lymph vessels or lymphatics) are thin-walled vessels (tubes), structured like blood vessels, that carry lymph. As part of the lymphatic system, lymph vessels are complementary to the cardiovascular system. Lymph vessel ...
which ascend from the convex surface of the
liver
The liver is a major Organ (anatomy), organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of proteins and biochemicals necessary for ...
* Two or three anterior mediastinal
lymph nodes
A lymph node, or lymph gland, is a kidney-shaped organ of the lymphatic system and the adaptive immune system. A large number of lymph nodes are linked throughout the body by the lymphatic vessels. They are major sites of lymphocytes that includ ...
* The small
mediastinal branches of the
internal thoracic artery
In human anatomy, the internal thoracic artery (ITA), previously commonly known as the internal mammary artery (a name still common among surgeons), is an artery that supplies the anterior chest wall and the breasts. It is a paired artery, with on ...
*
Thymus
The thymus is a specialized primary lymphoid organ of the immune system. Within the thymus, thymus cell lymphocytes or ''T cells'' mature. T cells are critical to the adaptive immune system, where the body adapts to specific foreign invaders. ...
(involuted in adults)
*superior and inferior sternopericardial ligaments
;Middle mediastinum
Bounded:
pericardial sac
The pericardium, also called pericardial sac, is a double-walled sac containing the heart and the roots of the great vessels. It has two layers, an outer layer made of strong connective tissue (fibrous pericardium), and an inner layer made of ...
– It contains the vital organs and is classified into the serous and fibrous pericardium.
;Contents
* the
heart
The heart is a muscular organ in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide t ...
enclosed in the
pericardium
The pericardium, also called pericardial sac, is a double-walled sac containing the heart and the roots of the great vessels. It has two layers, an outer layer made of strong connective tissue (fibrous pericardium), and an inner layer made of ...
* the
ascending aorta
The ascending aorta (AAo) is a portion of the aorta commencing at the upper part of the base of the left ventricle, on a level with the lower border of the third costal cartilage behind the left half of the sternum.
Structure
It passes obliqu ...
* the lower half of the
superior vena cava
The superior vena cava (SVC) is the superior of the two venae cavae, the great venous trunks that return deoxygenated blood from the systemic circulation to the right atrium of the heart. It is a large-diameter (24 mm) short length vein th ...
with the
azygos 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 ...
opening into it
* the
bifurcation of the trachea
In anatomy, the carina or tracheal bifurcation is a ridge of cartilage in the trachea that occurs between the division of the two main bronchi.
Structure
The carina occurs at the lower end of the trachea (usually at the level of the 4th to 5t ...
and the two
bronchi
A bronchus is a passage or airway in the lower respiratory tract that conducts air into the lungs. The first or primary bronchi pronounced (BRAN-KAI) to branch from the trachea at the carina are the right main bronchus and the left main bronchus. ...
* the
pulmonary trunk
A pulmonary artery is an artery in the pulmonary circulation that carries deoxygenated blood from the right side of the heart to the lungs. The largest pulmonary artery is the ''main pulmonary artery'' or ''pulmonary trunk'' from the heart, and t ...
dividing into its two branches
* the right and left
pulmonary veins
The pulmonary veins are the veins that transfer oxygenated blood from the lungs to the heart. The largest pulmonary veins are the four ''main pulmonary veins'', two from each lung that drain into the left atrium of the heart. The pulmonary vein ...
* the
phrenic nerves
* some bronchial
lymphatic glands
A lymph node, or lymph gland, is a kidney-shaped organ of the lymphatic system and the adaptive immune system. A large number of lymph nodes are linked throughout the body by the lymphatic vessels. They are major sites of lymphocytes that inclu ...
* pericardiocophrenic vessels
;Posterior mediastinum
Is bounded:
* Anteriorly by (from above downwards): bifurcation of
trachea
The trachea, also known as the windpipe, is a Cartilage, cartilaginous tube that connects the larynx to the bronchi of the lungs, allowing the passage of air, and so is present in almost all air-breathing animals with lungs. The trachea extends ...
; pulmonary vessels; fibrous pericardium and posterior sloping surface of
diaphragm
* Inferiorly by the thoracic surface of the
diaphragm (below);
* Superiorly by the transverse thoracic plane;
* Posteriorly by the bodies of the
vertebral column
The vertebral column, also known as the backbone or spine, is part of the axial skeleton. The vertebral column is the defining characteristic of a vertebrate in which the notochord (a flexible rod of uniform composition) found in all chordata, ...
from the lower border of the fifth to the twelfth
thoracic vertebra
In vertebrates, thoracic vertebrae compose the middle segment of the vertebral column, between the cervical vertebrae and the lumbar vertebrae. In humans, there are twelve thoracic vertebrae and they are intermediate in size between the cervical ...
(behind);
* Laterally by the
mediastinal pleura
The pulmonary pleurae (''sing.'' pleura) are the two opposing layers of serous membrane overlying the lungs and the inside of the surrounding chest walls.
The inner pleura, called the visceral pleura, covers the surface of each lung and dips b ...
(on either side).
* artery
**
thoracic part of the
descending aorta
In human anatomy, the descending aorta is part of the aorta, the largest artery in the body. The descending aorta begins at the aortic arch and runs down through the chest and abdomen. The descending aorta anatomically consists of two portions o ...
* veins
**
azygos 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 ...
** 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, essen ...
and the
accessory hemiazygos vein
The accessory hemiazygos vein, also called the superior hemiazygous vein, is a vein on the left side of the vertebral column that generally drains the fourth through eighth intercostal spaces on the left side of the body.
Structure
The accessor ...
* nerves
**
vagus nerve
The vagus nerve, also known as the tenth cranial nerve, cranial nerve X, or simply CN X, is a cranial nerve that interfaces with the parasympathetic control of the heart, lungs, and digestive tract. It comprises two nerves—the left and right ...
**
splanchnic nerves
The splanchnic nerves are paired visceral nerves (nerves that contribute to the innervation of the viscera, innervation of the internal organs), carrying fibers of the autonomic nervous system (visceral efferent fibers) as well as sensory fibers fr ...
**
sympathetic chain
The sympathetic trunks (sympathetic chain, gangliated cord) are a paired bundle of nerve fibers that run from the base of the skull to the coccyx. They are a major component of the sympathetic nervous system.
Structure
The sympathetic trunk lies j ...
*
esophagus
The esophagus (American English) or oesophagus (British English; both ), non-technically known also as the food pipe or gullet, is an organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to the ...
*
thoracic duct
In human anatomy, the thoracic duct is the larger of the two lymph ducts of the lymphatic system. It is also known as the ''left lymphatic duct'', ''alimentary duct'', ''chyliferous duct'', and ''Van Hoorne's canal''. The other duct is the right ...
* some
lymph glands
A lymph node, or lymph gland, is a kidney-shaped organ of the lymphatic system and the adaptive immune system. A large number of lymph nodes are linked throughout the body by the lymphatic vessels. They are major sites of lymphocytes that include ...
File:Gray968.png , A transverse section of the thorax
The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the cre ...
, showing the contents of the middle and the posterior mediastinum
The mediastinum (from ) is the central compartment of the thoracic cavity. Surrounded by loose connective tissue, it is an undelineated region that contains a group of structures within the thorax, namely the heart and its vessels, the esophagu ...
.
Clinical significance
![Mediastinaladenopathy](https://upload.wikimedia.org/wikipedia/commons/9/95/Mediastinaladenopathy.png)
The mediastinum is frequently the site of involvement of various
tumors
A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...
:
* ''Anterior mediastinum'': substernal
thyroid
The thyroid, or thyroid gland, is an endocrine gland in vertebrates. In humans it is in the neck and consists of two connected lobes. The lower two thirds of the lobes are connected by a thin band of tissue called the thyroid isthmus. The thy ...
goiter
A goitre, or goiter, is a swelling in the neck resulting from an enlarged thyroid gland. A goitre can be associated with a thyroid that is not functioning properly.
Worldwide, over 90% of goitre cases are caused by iodine deficiency. The term is ...
s,
lymphoma
Lymphoma is a group of blood and lymph tumors that develop from lymphocytes (a type of white blood cell). In current usage the name usually refers to just the cancerous versions rather than all such tumours. Signs and symptoms may include enlar ...
,
thymoma
A thymoma is a tumor originating from the epithelial cells of the thymus that is considered a rare malignancy. Thymomas are frequently associated with neuromuscular disorders such as myasthenia gravis; thymoma is found in 20% of patients with mya ...
, and
teratoma
A teratoma is a tumor made up of several different types of tissue, such as hair, muscle, teeth, or bone. Teratomata typically form in the ovary, testicle, or coccyx.
Symptoms
Symptoms may be minimal if the tumor is small. A testicular terato ...
.
* ''Middle mediastinum'': lymphadenopathy, metastatic disease such as from small cell carcinoma from the lung.
* ''Posterior mediastinum'': Neurogenic tumors, either from the nerve sheath (mostly benign) or elsewhere (mostly malignant).
Mediastinitis
Mediastinitis is inflammation of the tissues in the mid-chest, or mediastinum. It can be either Acute (medical), acute or Chronic (medical), chronic. It is thought to be due to four different etiologies:
* direct contamination
* hematogenous or Ly ...
is
inflammation
Inflammation (from la, wikt:en:inflammatio#Latin, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or Irritation, irritants, and is a protective response involving im ...
of the tissues in the mediastinum, usually
bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...
l and due to rupture of organs in the mediastinum. As the infection can progress very quickly, this is a serious condition.
Pneumomediastinum
Pneumomediastinum (from Greek ''pneuma'' – "air", also known as mediastinal emphysema) is pneumatosis (abnormal presence of air or other gas) in the mediastinum, the central part of the chest cavity. First described in 1819 by René Laennec, th ...
is the presence of air in the mediastinum, which in some cases can lead to
pneumothorax
A pneumothorax is an abnormal collection of air in the pleural space between the lung and the chest wall. Symptoms typically include sudden onset of sharp, one-sided chest pain and shortness of breath. In a minority of cases, a one-way valve ...
,
pneumoperitoneum
Pneumoperitoneum is pneumatosis (abnormal presence of air or other gas) in the peritoneal cavity, a potential space within the abdominal cavity. The most common cause is a perforated abdominal organ, generally from a perforated peptic ulcer, althou ...
, and
pneumopericardium
Pneumopericardium is a medical condition where air enters the pericardial cavity. This condition has been recognized in preterm neonates, in which it is associated with severe lung pathology, after vigorous resuscitation, or in the presence of assi ...
if left untreated. However, that does not always occur and sometimes those conditions are actually the cause, not the result, of pneumomediastinum. These conditions frequently accompany
Boerhaave syndrome
Esophageal rupture is a rupture of the esophageal wall. Iatrogenic causes account for approximately 56% of esophageal perforations, usually due to medical instrumentation such as an endoscopy or paraesophageal surgery. In contrast, the term Boerh ...
, or spontaneous
esophageal rupture.
Widening
''Widened mediastinum/mediastinal widening'' is where the mediastinum has a width greater than 6 cm on an upright PA
chest X-ray
A chest radiograph, called a chest X-ray (CXR), or chest film, is a projection radiograph of the chest used to diagnose conditions affecting the chest, its contents, and nearby structures. Chest radiographs are the most common film taken in med ...
or 8 cm on supine AP chest film.
A widened mediastinum can be indicative of several pathologies:
*
aortic aneurysm
An aortic aneurysm is an enlargement (dilatation) of the aorta to greater than 1.5 times normal size. They usually cause no symptoms except when ruptured. Occasionally, there may be abdominal, back, or leg pain. The prevalence of abdominal aortic ...
*
aortic dissection
Aortic dissection (AD) occurs when an injury to the innermost layer of the aorta allows blood to flow between the layers of the aortic wall, forcing the layers apart. In most cases, this is associated with a sudden onset of severe chest or ...
*
aortic unfolding
*
aortic rupture
Aortic rupture is the rupture or breakage of the aorta, the largest artery in the body. Aortic rupture is a rare, extremely dangerous condition. The most common cause is an abdominal aortic aneurysm that has ruptured spontaneously. Aortic rupture ...
*
hilar lymphadenopathy
Lymphadenopathy or adenopathy is a disease of the lymph nodes, in which they are abnormal in size or consistency. Lymphadenopathy of an inflammation, inflammatory type (the most common type) is lymphadenitis, producing swelling (medical), swolle ...
*
anthrax inhalation - a widened mediastinum was found in 7 of the first 10 victims infected by anthrax (''Bacillus anthracis'') in 2001.
*
esophageal rupture
Esophageal rupture is a rupture of the esophageal wall. Iatrogenic causes account for approximately 56% of esophageal perforations, usually due to medical instrumentation such as an endoscopy or paraesophageal surgery. In contrast, the term Boerh ...
- presents usually with
pneumomediastinum
Pneumomediastinum (from Greek ''pneuma'' – "air", also known as mediastinal emphysema) is pneumatosis (abnormal presence of air or other gas) in the mediastinum, the central part of the chest cavity. First described in 1819 by René Laennec, th ...
and
pleural effusion
A pleural effusion is accumulation of excessive fluid in the pleural space, the potential space that surrounds each lung.
Under normal conditions, pleural fluid is secreted by the parietal pleural capillaries at a rate of 0.6 millilitre per kilog ...
. It is diagnosed with water-soluble swallowed contrast.
*
mediastinal mass
A mediastinal tumor is a tumor in the mediastinum, the cavity that separates the lungs from the rest of the chest. It contains the heart, esophagus, trachea, thymus, and aorta. The most common mediastinal masses are neurogenic tumors (20% of medi ...
*
mediastinitis
Mediastinitis is inflammation of the tissues in the mid-chest, or mediastinum. It can be either Acute (medical), acute or Chronic (medical), chronic. It is thought to be due to four different etiologies:
* direct contamination
* hematogenous or Ly ...
*
cardiac tamponade
Cardiac tamponade, also known as pericardial tamponade (), is the buildup of fluid in the pericardium (the sac around the heart), resulting in compression of the heart. Onset may be rapid or gradual. Symptoms typically include those of obstruct ...
*
pericardial effusion
A pericardial effusion is an abnormal accumulation of fluid in the pericardial cavity. The pericardium is a two-part membrane surrounding the heart: the outer fibrous connective membrane and an inner two-layered serous membrane. The two layers of t ...
*
thoracic vertebrae fracture
A spinal fracture, also called a vertebral fracture or a broken back, is a fracture affecting the vertebrae of the spinal column. Most types of spinal fracture confer a significant risk of spinal cord injury. After the immediate trauma, there i ...
s in trauma patients.
See also
*
Mediastinum testis
The mediastinum testis is a network of fibrous connective tissue that extends from the top to near the bottom of each testis. It is wider above than below.
Numerous imperfect septa are given off from its front and sides, which radiate toward the s ...
(unrelated structure in the
scrotum
The scrotum or scrotal sac is an anatomical male reproductive structure located at the base of the penis that consists of a suspended dual-chambered sac of skin and smooth muscle. It is present in most terrestrial male mammals. The scrotum cont ...
)
*
Mediastinal germ cell tumor
Mediastinal germ cell tumors are tumors that derive from germ cell rest remnants in the mediastinum. They most commonly occur in the gonad but occasionally elsewhere.
Signs and symptoms
Unlike benign germ cell tumors of the mediastinum, malignant ...
*
Mediastinitis
Mediastinitis is inflammation of the tissues in the mid-chest, or mediastinum. It can be either Acute (medical), acute or Chronic (medical), chronic. It is thought to be due to four different etiologies:
* direct contamination
* hematogenous or Ly ...
*
Mediastinal tumor
A mediastinal tumor is a tumor in the mediastinum, the cavity that separates the lungs from the rest of the chest. It contains the heart, esophagus, trachea, thymus, and aorta. The most common mediastinal masses are neurogenic tumors (20% of medias ...
References
External links
* – "Divisions of the mediastinum."
* – "The anatomical divisions of the inferior mediastinum."
* – "Subdivisions of the Thoracic Cavity"
{{Authority control
Thoracic cavity