SUPERIOR MEDIASTINUM
Mediastinum
The region between the pleural sacs, containing
the heart and all of the thoracic viscera except the lungs.
Also called interpleural space, mediastinal space.
Extent:
Superior: thoracic inlet
Anterior: sternum and C.C
Inferior: diaphragn
Posterior: bodies of thoracic vertebrae.
Divisions of the Mediastinum
Above the level of pericardium.
Superior mediastinum
Below the level of pericardium
1. Anterior mediastinum
2. Middle mediastinum
3. Posterior mediastinum
Superior Mediastinum
Boundaries
1. Superior-Plane of the thoracic inlet
2. Inferior-Transverse thoracic plane (line drawn from sternal angle to T4)
3. Anterior–manubrium of the sternum
4. Posterior –Anterior surface of bodies of vertebrae T1 through T4
5. Lateral-mediastinal pleura
Superior mediastinum
Contents
Arteries:
Aortic arch
Brachiocephalic artery
Thoracic portion of left common carotid
Left subclavian
Veins:
Brachiocephalic veins.
Upper half of the superior vena cava
Left highest intercostal vein


Nerves:
Vagus nerve
Phrenic nerve
Left recurrent laryngeal nerve
Superficial and deep cardiac plexuses.
viscera
•Trachea
•Thoracic duct
•Thymus
•Esophagus
Thymus
The thymus is a specialized organ in the immune system.
The only known function of the thymus is the production of T-lymphocytes (T
cells), which are critical cells of the adaptive immune system
Present on either side of the midline behind manubrium.
Covered by converging pleura of the lungs.
Situated partly in the thorax, partly in the neck,extending from
4th costal cartilage upto the thyroid resting on the pericardium
Thymus continues to grow until the time of puberty and then begins to atrophy.
it continues to function as an endocrine gland important in stimulating the
immune system.


Blood
supply:
Internal mammary artery
Superior and inferior thyroids
Venous drainage:
left innominate into the thyroid veins.
Nerves:
vagus nerve
Thoracic duct
Thoracic duct is the largest lymphatic vessel in
the body
38-45cm in length and an average diameter of
about 5mm
It begins in the abdomen as a confluence of right
and left lumbar trunk and intestinal trunk, forming
a triangular dilation ,the cisterna chyli (chyle cistern), which drains the
abdominal viscera and walls, pelvis, perineum,
and lower limbs.

Termination of Thoracic Duct
It terminates by joining the left brachiocephalic vein
in the angle between left Internal jugular vein and
left subclavian vein
The thoracic duct has several valves; at its termination it is provided with a pair,
the free borders of which are turned toward the vein, so as to prevent the
passage of venous blood into the duct.
Trachea
The trachea or windpipe is a cartilaginous and membranous tube
Extends from the lower part of the larynx, on a level with C6, to the upper border
of T5, where it divides into 2 bronchi, one for each lung
11 cm. in length; its diameter, is from 2 to 2.5 cm.,always greater in males.
There are about fifteen to twenty incomplete C-shaped cartilaginous rings

Relations of trachea in the thorax
Anterior:
Manubrium sterni
Thymus
Left brachiocephalic vein,
Aortic arch,
Left common carotid artery.
Deep cardiac plexus.
Posterior:
Esophagus
Lateral:
Right-pleura and right vagus,
Left- left recurrent nerve,
aortic arch,
left common carotid and
subclavian arteries.
Right bronchus
wider, shorter, and more vertical in direction
2cm long
Enters the lung at T5
Left bronchus
smaller in caliber but longer than the right
Enters the lung at T6
Arterial supply:
Inferior thyroid arteries.
veins
Thyroid venous plexus.
nerves
Vagus and the
Recurrent nerves, and from the sympathetic; distributed to the Trachealis
muscles and between the epithelial cells.
Aorta
Divided
into:
Ascending aorta
Arch of aorta
Descending aorta
Thoracic aorta
Abdominal aorta
Arch of aorta
Begins at the level of right 2nd sternocostal joint
Runs upward, backward to the left in front of trachea
above the left pulmonary artery
Directed backward on the left side of trachea
Passes downward on the left side of T4
Upper border of arch is 2.5cm below the upper border
of manubrium.

Relations of arch of aorta
Left
Pleura
Vagus nerve
Left phrenic nerve
Right
Trachea
Esophagus
Left recurrent laryngeal nerve
Superior vena cava
Right phrenic nerve
Anterior
Thymus
Superficial cardiac plexus
Inferior
Ligamentum arteriosum
Left recurrent laryngeal nerve
Bifurcation of pulmonary trunk
Deep cardiac plexus
Branches of aortic arch
Innominate artery(brachiocephalic artery)
Largest branch
4-5cm in length
Arises at 2nd right costal cartilage
Divides into right common carotid and right subclavian
Left common carotid artery
Arises from arch at the level of 2nd left costal cartilage
Divides into external carotid and internal carotid artery

Left subclavian artery
Arises at the level of T4
Continues in the axilla as axillary artery
THE LIGAMENTUM ARTERIOSUM
IT IS A FIBROUS BAND THAT CONNECTS THE
BIFURCATION OF THE PULMONARY TRUNK TO
THE LOWER CONCAVE SURFACE OF THE AORTIC
ARCH.
Right Brachiocephalic Vein
2.5
cm. in length
behind sternal end of clavicle
Passes vertically down and join left brachiocephalic to form superior vena cava
Formed From:
Right internal jugular.
Right subclavian.
Tributaries:
Right internal intercostal vein.
Right internal mammary
Right inferior thyroid veins
Begins
Relations of right brachiocephalic vein
Posteromedial:
Right brachiocephalic artery
Right vagus nerve interposed between trunks
and vein
Posterolateral:
Phrenic nerve
Internal thoracic artery passing from posterior
to anterior
Lateral and superior:
First rib superior to apex of right lung
Anterior:
Sternum and thymus inferiorly

Left Brachiocephalic Vein
6cm in length
Begins behind the sternla end of left clavicle
Comes to the right to join right brachiocephalic to form sup vena cava
Formed from:
Left internal jugular vein.
Left subclavian vein.
Tributaries:
Left internal thoracic vein.
Left superior intercostal.

Inferior thyroid veins.
Superior Vena Cava
carries deoxygenated blood from the upper half of the body to the heart's right
atrium
No valve separates the superior vena cava from the right atrium
About 7cm in length
st
Begins at the level of 1 right costal cartilage
Formed from:
Right brachiocephalic vein.
Left brachiocephalic vein.
Receives:
Azygos vein.

Relations of superior vena cava
Anterior
Right lung and pleura
Posterior
Right vagus nerve
Right
Phrenic nerve
Right pleura
Left
Ascending aorta
Cardiac plexus
The cardiac plexus is a plexus of nerves situated at the base of the heart that
innervate the heart.
Divided into:
Superficial
Deep
Right half
Left half

Superficial part of cardiac plexus
Located below arch of aorta in front of right pulmonary artery
Formed from
Superior cardiac branch of the left sympathetic trunk
Lower superior cervical cardiac branch of the left vagus nerve.
 The superficial part of the cardiac plexus gives branches to
a. Deep part of the plexus
b. Anterior coronary plexus;
c. Left anterior pulmonary plexus.
Deep part of cardiac plexus
The deep part of the cardiac plexus is situated in front of the bifurcation of the
trachea, above the point of division of the pulmonary artery, and behind the aortic
arch.
formed by the cardiac nerves derived from the cervical ganglia of the
sympathetic trunk, and the cardiac branches of the vagus and recurrent laryngeal
nerves.
Subdivided into
Right half gives branches to
Anterior pulmonary plexus
Anterior coronary plexus
Posterior coronary plexus
Left half gives branches to
Anterior pulmonary plexus
Posterior coronary plexus
Phrenic nerve
Right phrenic nerve descends in the
thorax along the right side of the
right brachiocephalic vein and the
superior vana cava
Pathway
Passes in front of the root of the right lung
And runs along the right side of the pericardium
Descends on the right side of the inferior
vena cava to the diaphragm
Branches.
Terminal branches supply the musculature
of the right half of the diaphragm and
pass through the caval opening of the diaphragm
to supply the central part of the peritoneum

Right vagus nerve
Descends in the thorax, posterolaterally to the
brachiocephalic artery,
the lateral to the trachea and medial to the
terminal part of the azygos vein.
It passes behind the root of the right lung,assists in the formation of the
pulmonary plexus
On leaving the plexus,the vagus passess to th posterior surface of esophagu and
will be followed later in the posterior mediastinum
Left vagus nerve
Descends
ito the thorax between the left common carotid and left subclavian
arteries.it then crosses the left side of the aortic arch
And
is itself crossed by the left phrenic nerve.the vagus then turns posteriorly
behind the root of the lung and assists in the formation of the pulmonary
plexus.on leaving the plexus vagus comes to the anterior of esophagus and will b
followed later in the posterior mediastinum
Left recurrent laryngeal nerve
left recurrent laryngeal nerve an important branch
of the left vagus. The left recurrent laryngeal nerve hooks
around the lower border of the ligamentum arteriosum
and eventually ascends in the interval between the
trachea and the esophagus to reach the larynx.

Applied anatomy
HOARSENESS of voice due to damage to recurrent laryngeal nerve
PARALYSIS OF DIAPHRAGM due to damage to phrenic nerve
THORACIC INLET SYNDROME