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Posterior Mediastinum

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Boundaries

Anterior:

Pericardium & diaphragm

Posterior:

T5

T12

Superior:

??

Inferior:

diaphragm

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Contents

1. Descending thoracic aorta

2. Azygos & hemiazygos veins

3. Thoracic duct

4. Sympathetic trunk

5. Esophagus

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Thoracic Aorta

Starts left to inf. T4 body

As it descends shifts to midline

Terminates:

ant. to T12 body (opening??)

Pass posterior to lf. Lung root

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Branches

1. Bronchial a. (3):trachea, bronchi & lungs

2. Esopahgeal a. (which 1/3 ?)

3. Pericardial a.

4. Superior phrenic a.

5. Posterior intercostal a.:9 pairs (3rd-11th)

6. ??

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Azygos System of Veins

(G, unpaired)

Drains Post. thoracoabdominal walls

Exhibits Many variations

3 veins:

Azygos (Rt.)

Inf. hemiazygos (Lf.)

Sup. (accessory) hemiazygos (Lf.)

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Azygos Vein

Formed by: ???

Rt. To aorta

Aortic hiatus (Rt. T12) T5Arches over the root of Rt.

lung

Opens into post. SVC (T5)

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Inferior Hemiazygos Vein

On Left side

From T12 T8

Drains:Lower Lf. Post. intercostal vein

(9th-11th, & subcostal)

At T8:

Turns to Rt. azygos vein

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Accessory Hemiazygos

On left side (superiorly)

Receives:

4th-8th Lf. Post. intercostal v.

At T 7:

Turns to Rt. azygos vein

Azygos system provides alternativepathway between

SVC & IVC

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LymphaticThoracic Duct

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Thoracic Duct

The largest lymph duct in the body

Begins in abdomen as a dilated sac

(cisterna chyli)

Aortic Hiatus

(between aorta & azygos)

Lf. Brachiocephalic Vein

(Jxn: Int. jugular & Subclavian)

Drains lymph from all body except:

Rt. Thorax, Rt. Upper limb, Rt. Head & Neck

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Right Lymphatic Duct

Drains:

Rt. Thorax

Rt. Upper Limb

Rt. Head & Neck

Opens:

Junx of Rt. Internal jugular

& Rt. Subclavian

Communicates with thoracic duct

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Sympathetic Trunk (Chain)

A chain of ganglia that receives thesympathetic autonomic neurons &distribute them to different bodyparts

Ganglion: a cluster of neuronal cellbodies

Sympathetic chain:

cervical (3) / thoracic / abdominal / &pelvic

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Thoracic Part of Sympathetic Chain

Most lat. Structure in mediastinum

Runs on the heads of the ribs

Leaves behind medial arcuate lig.

1st thoracic + inf. cervical

Stellate ganglion

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Esophagus

A tubular structure Begins opposite to C6 as a continuation of thepharynx & ends in the stomach

3 parts:

cervical

thoracic (relations)

abdominal

Pass through sup. & post.mediastinum

Then through esophageal opening

(which vertebral level?)

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Thoracic Part Relations

Anterior:

Trachea & Lf. Recurrent laryngeal n.

(Superior Mediastinum)

Posterior:Bodies of thoracic vrtebrae

Then

Descending aorta

Thoracic ductAzygos vein

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Right:

Mediastinal pleura &

azygos vein (as it arches)

Left:

Aortic arch & Lf. subclavian a

Superior part of thoracic duct

Vagus nerves join the esophagus &rotate around as it passes through

the diaphragm:

Rt. Vagus = posterior

Lf. Vagus = anterior

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