ميحرلا نمحرلا الله مسب the mediastinum · dr.shireen anatomy (thorax) 24/4/2012...

24/4/2012 Anatomy (Thorax) Dr.shireen

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بسم هللا الرحمن الرحيم

The Mediastinum

Today, we will take the contents of the mediastinum.

We will divide the contents of the mediastinum

in two aspects:

1- From Posterior to Anterior (for The

Superior mediastinum)

2-From Superior to Inferior.

:Posterior to Anterior From 1)

Posterior Middle Anterior

(Tubal layer) (Arterial layer) (Venous layer)

Tubal layer :

It has two contents: 1- Esophagus

2-Trachea

1) Esophagus (A Revision):

Length: 10 inches (25 cm).

Origin: It starts as a continuation

of the Pharynx (بلعوم ) in The

lower Border of C6 (Important

landmark).


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Shape: Muscular Tube.

Site: It's divided into two parts; the first one is in

the Superior mediastinum and the second is in the

Inferior mediastinum (Posterior part).

End: It passes through a special opening in The

Diaphragm and then continues as a stomach.

Relations:

The Right side: Related to the right lung

(makes an impression on the right lung) .

The Left side: - it makes an impression on the

left lung at the upper part ( superior

mediastinum) .

- Left to the Esophagus

at thoracic aorta DescendingThe there is

.the inferior mediastinum

Anterior: -There is The Trachea at the superior

mediastinum .

-There is The Heart at the Inferior

mediastinum.

Posterior: There is the vertebral column.

Blood Supply: The Aorta.

Note: Any content in the Mediastinum takes The

Arterial supply from The Aorta.


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2) Trachea:

Length: 10 cm.

Origin: starts as a continuation of Larynx (الحنجرة)

in the lower Border of C6 (important landmark).

Site: It's considered to be a content of Superior

mediastinum because it ends at the line between

Superior and Inferior mediastinum.

Relations:

Anterior: There is The Arch of The Aorta.

Posterior: There are Esophagus and the Vertebral

column.

The Right side: Related to the right lung (It makes

an impression on the right lung).

Left Side: There is The Aortic Arch so it doesn’t

make any impression on the left lung.

Note: The Aortic Arch has Double Relations with The

Trachea; Firstly, It is Anterior to The Trachea Then it

turns to the left side of

Trachea.

End: it Makes a

Bifurcation (تشعب) and

gives Two Bronchi;

Left & Right, at The

Line between The

Superior and Inferior

mediastinum.


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Note: The differences below can't be distinguished in the

picture but they are true.

Left bronchus Right bronchus

Longer Shorter Length Narrower Wider Width Makes an Obtuse angle (135o)

Continuation of Trachea(in the same direction)

Orientation

___________

Divides into two Branches before it enters The Hilum of the right lung

Divisions

Note: Because of The divisions of the right bronchus, we

found the bronchus in the right hilum divided into Eparterior

and Hyparterior.

Clinical Application:

**Suppose that you are in the Emergency Section, and a child

( ( Inhaled Foreign Body) كة أو غطا ألم مسلا شرق في أست (

-This Body will enter easily to the Right Bronchus because

it's a continuation of Trachea, wider and shorter.

:Remember These landmarks


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Arterial Layer: ((We have just one artery

(The Aorta).)) The Aorta starts as the Ascending aorta which

comes from the left ventricle, and then the

ascending aorta converts to The Arch of the

Aorta then to the descending Aorta.

The Descending Aorta divides into two parts;

the first (Descending thoracic Aorta) inside

the Thorax, and the other part (Descending

Abdominal Aorta) enters the Abdomen through

the diaphragm.

**Now we will take origin, end and branches of each

part of The Aorta.

1) The Ascending Aorta :

Origin: starts from the left ventricle posterior to

the pulmonary trunk.

It is Directed Anterior (Forward).

End: In the Line between the Superior and

Inferior mediastinum.

Branches: Gives two Branches (Right & Left

coronary arteries).

2) The Arch of Aorta:

Origin: Starts as a continuation of the

Ascending Aorta at The level of Sternal Angle

directed anteriorly.


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Then It's Directed Posterior (backward).

End: At the Same Level where It starts

(between T4 and T5).

Branches:

Left common carotid artery

Left Side (It goes to the Head & Neck).

Left Subclavian Artery

(It goes to the left Upper Limb).

Right Common carotid

Right Side Brachiocephalic (To the Head & Neck)

Right Subclavian artery

(To the Right Upper limb).

o Right Subclavian

&carotid artery both

branch from

Single Trunk

(Brachiocephalic).


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o There are Two impressions (grooves) for the left

common carotid (anterior) and left subclavian

(posterior) in the left lung.

3) The Descending Thoracic Aorta:

Origin: Starts as a continuation of the arch

between T4 & T5, and then continues in the

Inferior mediastinum (Posterior part).

End: It passes through a special opening in the

diaphragm and continues as Abdominal Aorta.

Branches :

Paired Single

-Post. Intercostals -Fibrous Pericardial

-Bronchial - Mediastinal

-Subcostal -Esophageal

-Phrenic

Venous Layer:

o The Right and the left side are Nearly the same.


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o Right internal Jugular and Right subclavian unite to

make Right Brachiocephalic.

Note: The left side has the same veins.

o The Difference between The two sides:

- Right Brachiocephalic is shorter than left

Brachiocephalic because the left one crosses the

midline from left to right side but the right

brachiocephalic stays in the right side (Look at

the picture).

o Finally, the right &

left brachiocephalic

veins unite opposite

to the right first

costal cartilage to

give the Superior

Vena Cava.

The Superior Vena

Cava (SVC) :

o Takes the venous drainage from Head, Neck

and Upper limbs.

Origin: Starts as a union of right and left

brachiocephalic veins opposite the right first

costal cartilage.

Length: 3 inches.

Course: passes in the Superior mediastinum

then in the Inferior (Middle mediastinum).


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End: In the 3rd costal cartilage and drains in

the right atrium.

o There is a tributary (Azygos vein) exactly in the

middle of (SVC) (2nd costal cartilage).

Now, we will take the contents of the mediastinum

from Superior to inferior:

2) From Superior to Inferior:

Superior

mediastinum:

Esophagus

Trachea

Arch of aorta and its

big branches (Brachiocephalic,

left common carotid

and left subclavian)

Brachiocephalic

veins

Upper Half of Superior Vena Cava


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Inferior mediastinim:

Middle part:

The Heart –the fibroserous sac surrounding it

(pericardium).

-The vessels entering the heart (lower half

of SVC & upper half of IVC).

-The vessels leaving the heart (pulmonary

trunk & Ascending Aorta)

Posterior part:

Esophagus

Descending Thoracic Aorta

Azygos and hemiazygos veins

The impressions in the

medial surface of lung:

(Important for the lab)

Right lung: (look at the

picture).

Esophagus (most

posterior)

Trachea

Rt. Brachiocephalic

vein & SVC

Cardiac impression(right atrium)


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Left lung: (Look at the

picture).

Aorta (Arch and

descending Aorta)

Esophagus

Left subclavian

Left common carotid

artery

Cardiac

impression(left

ventricle)

وحنبدا االسبوع الجاي ان شاء هللا في ال Thoraxوكدا دحنا خلصنا ال

Abdomen.

The more you can dream, the more can you do,

So make your dreams infinite.

With my best wishes,

Your colleague: Mohannad Abo Hamad

ميحرلا نمحرلا الله مسب the mediastinum · dr.shireen anatomy (thorax) 24/4/2012...

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