The Superior Mediastinum E-learning

7/31/2019 The Superior Mediastinum E-learning

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The Superior Mediastinum


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Boundaries

Sup.: Anatomical thoracic inlet

Inf.: Imaginary line

Ant.: manubrium

Post.: T1-T4


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Contents

1. Brachiocephalic veins & SVC

2. Aortic arch & branches:

brachiocephalic

lf. C.C.a.

Lf. Subclavian a.

3. Vagus & Phrenic n.

4. Trachea

5. Esophagus


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Brachiocephalic Veins

Formed by union : Int. Jug. v. & Subclavian v.

(at sternoclavicular joints)

Lf.: longer (6 cm)

pass post. to manubrium

ant. to aortic branches

Rt.: 2-3 cm

vertical to right 1st

cc

Unite behind Rt. 1st cc to form SVC


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Superior Vena Cava (SVC)

Starts behind Rt. 1st

cc

Ends behind Rt. 3rd cc

Rt. Atrium

Relations:Ant.: Rt. Lung & covering pleura

Post.: root of Rt. Lung

Medial: Ascending aorta

Lateral: Rt. Phrenic & Rt. lung

Tributaries:

Azygos Vein:path & drainage? 3


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posteroanterior chest x-ray

SVC


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Aorta

4 Parts:

1. Ascending Aorta:

lies within fibrous pericardium

sup. to Rt. Until Rt. 2nd cc

2 branches?

2. Arch:

curved continuation (sup. mediast)

Rt. 2nd cc

arches supero-posterior to Lf. Side

infero-posteriorLf. Side of T4 body

3 branches?


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3. Descending Thoracic Aorta:

within post. mediastinumpost. intercostal a. (except?)

subcostal a.

bronchial, pericardial & esophageal

opposite to T12 (aortic opening)

4. Abdominal Aorta:

starts at T12- L1

ends by dividing into:

Rt. & Lf. common iliac a.

at L4


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Arch of Aorta

Start ? Ends?

Relations:

Arches over:

Rt. Pulmonary a. & Lf. Main bronchus

Crossed ant.:Lf. Vagus & phrenic n.

Rt.:

Trachea & Esophagus

Lf. Recurrent laryngeal n. loops aroundthe arch as it arise from the vagus


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posteroanterior chest x-ray

Aorta:

Ascending& arch


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Branches of The Arch

1. Brachiocephalic a.: (Rt.)

largest branch

S-C joint Rt. CC a. & Rt. Subclavian a.

2. Lf. Common Carotid a.:enters the neck at S-C joint

3. Lf. Subclavian a.:

most post. branchloops over 1st rib upper limb


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Nerves in Mediastinum:

Vagus & Phrenic


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Vagus Nerve

CN X (parasympathetic)

Rt. Vagus:

- Lat. to the trachea

- Medial to azygos

- Post. to root of the Rt. lung

- Join esophagus:esophageal opening (Post.)

Gives Rt. Recurrent laryngeal n. that loops around subclavian a.


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Left Vagus

- Descends between lf. Cc & lf. Subc.

- ant. & Lf. to aortic arch

Lf. Recureent laryngeal n.

(read your textbook)

- Post. to lung root

- Join esophagus:

esophageal opening (ant.)


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Phrenic Nerve

C3, 4, 5

Motor:

Sole motor to diaphragm

Sensory: Sensory to central part of

diaphragm

Pericardium

Parietal pleura (mediastinal & ?)

Peritoneum (diaphragmatic)


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Rt. Phrenic

Descends lat. tobrachiocephalic & SVC

Ant. to root of Rt. Lung

Rt. Side of pericardium

Rt. to IVC:

caval opening


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Left Phrenic

Enters lf. To subclavian a.

Lat. To vagus n (X)

Ant. to root of Lf. Lung


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TracheaFibrocartilaginous tube

(C6-sternal angle)

In deep inspiration it reaches thelevel of ?

U-shaped bars of hyaline catilage

& smooth muscle (trachialis)

Rt. bronchus:Wider, shorter & more vertical

Lf. Bronchus:Narrower, longer & more horizontal

Relations of lf. bronchus?Inf. To ?, ant. To ??


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Tracheal Relations

Anterior:Lf. Brachiocephalic v. & manubrium

Posterior:

esophagus & recurrent laryngeal n.

Right:Rt. Vagus n. & Azygos v. (just inf.)

Left:Aortic arch, Lf. CC & Subclav. A & Lf. Vagus n.


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The Superior Mediastinum E-learning

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