Thoracic Duct

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Introduction

Formation

Course

Relations

Tributaries

Applied anatomy

Learning objectives

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Thoracic duct

- Is the largest lymphatic trunk which drains chyle(product of fat digestion) & most lymph of body.

- Extent- Upper abdomen at lower border of T12 to lower part of neck, crossing post & sup mediastinum

- 45cms long & 0.5cms wide

- Appears Beaded due to presence of many valves in its lumen 3

Drains lymph from whole of body except • Rt side of head & neck

• Rt upper limb

• Rt lung & thoracic wall

• Rt side of heart and rt surface of liver

Area of drainage

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Course of Thoracic Duct

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Course:

Begins in abdomen at lower border of T12 as a continuation of cisterna chyli

Enters post mediastinum through aortic opening of diaphragm(T12)

At T5 shifts to left & runs in superior mediastinum

At C7 (root of neck) arches laterally, then downwards

Ends at angle formed by union of left int jugular vein & lt subclavian vein, (regurge of blood prevented by a pair of valves)

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Relations

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Scalenus ant

Termination

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Termination

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Azygos vein

TS at T4 V level

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Tributaries:

Receives lymph from both halves below diaphragm through Cisternae chyli & Lt half above diaphragm

1. From post IC lymph nodes of lower 6 spaces

2. From upper lumbar nodes(paraaortic LN)

3. From Post Mediastinal lymph nodes & post IC LNs of upper 6 IC spaces

4. From axilla through Lt Subclavian trunk

5. From nodes in Lt ½ of H & N thru Lt Jugular trunk

6. From Lt half of thorax (Lt lung & Lt side of heart) through Lt Bronchomediastinal trunk

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Applied anatomy Obstruction of Thoracic duct – Due to mature

filarial parasites lymph vessels get burst chylothorax, chyloperitoneum, chyluria.

Cervical part of thoracic duct is damaged in block dissection of neck

Thoracic duct is very thin walled and colourless so more prone for injury during surgery in post mediastinum. 15