The thoracic duct is the largest lymphatic vessel in the body. It begins in the abdomen at the lower border of the T12 vertebrae and extends upwards through the posterior and superior mediastinum to the neck. At the C7 vertebral level, it arches laterally and drains into the junction of the left internal jugular and subclavian veins. It drains lymph from the entire body below the diaphragm and left side of the body above the diaphragm, receiving tributaries from lymph nodes and vessels along its course. Injuries or obstructions to the thin-walled thoracic duct can lead to fluid accumulation in the thorax or abdomen.

1. Thoracic
DucT
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2.  Introduction
 Formation
 Course
 Relations
 Tributaries
 Applied anatomy
Learning objectives
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3. 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

4. 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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5. 5

6. Course of Thoracic Duct
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7. 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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8. 8

9. 9

10. Relations
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11. Scalenus ant
Termination
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12. Termination
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13. Azygos vein
TS at T4 V level
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14. 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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15. 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