Human Anatomy Vol 1

Oesophageal atresia

Lower segment connected

to trachea

Fig" 20.9: Tracheo-oesophageal fistula

Feotures

The thoracic duct is the largest lymphatic vessel in the

body. It extends from the upper part of the abdomen

to the lower part of the neck, crossing the posterior and

superior parts of the mediastinum. It is about^45 crr:./

L8 inch long. It has a beaded appearance because of the

presence of many valves in its lumen (Fig.20.10).

Left internal jugular vein

Thoracic duct

Oesophagus

Left subclavian vein

Azygos vein

Descending thoracic aorta

Accessory hemiazygos vein

Hemiazygos vein

Cisterna chyli

Fig.20.10: The course of the thoracic duct

TRACHEA, OESOPHAGUS AND THORACIC DUCT

Course

The thoracic duct begins as a continuation of the uPPer

end of the cisterna chyli near the lower border of the

twelfth thoracic vertebra and enters the thorax through

the aortic opening of the diaphragm.

It then ascends through the posterior mediastinum

from level of 12th thoracic vertebra to 5th thoracic

vertebra where it crosses from the right side to the left

side. Then it courses through the superior mediastinum

along the left edge of the oesophagus and reaches the

neck.

In the neck, it arches laterally at the level of the

transverse process of seventh cervical vertebra. Finally

it descends in front of the first part of the left subclavian

artery and ends by opening into the angle of junction

between the left subclavian and left internal jugular

veins.

Relolions

Altha Aor*ic eningof the Diaphragm

Anteriorlv : Diaphragm.

Posteriorly : Vertebral column.

'Io the right: Azygos vein.

Ta the left: Aorta.

tn lke Posterior Mediastinum

Anteriorly

L Diaphragrn(see Figs 19.3 and 19.5).

(^2) Oesophagus.
(^3) Right pleural recess.
Posteriorly
(^1) Vertebral column.
2 Right posterior intercostal arteries.
3 Terminal parts of the hemiazygos veins (Fig. 20.10).
To the r t: Azygos vein.
To tlrc leTt; Descending thoracic aorta.
ln the Superior Me stifium
A:nteriorly
(^1) Arch of aorta.
2 The origin of the left subclavian artery.
P osteriorly : Vertebral column.
To the right: Oesophagus
To the left: Plet;ra.
tnlhe Neck
The thoracic duct forms an arch rising about 3-4 cm above
the clavicle. The arch has the following relations.
I