1. Introduction
- The thoracic
duct is the largest lymphatic vessel in the body.
- It drains
lymph from the entire body except:
- Right
upper limb
- Right
thorax
- Right
half of head & neck (these are drained by the right lymphatic duct)
2. Length and Course
- Length: About
45 cm (18 inches)
- Begins in
the abdomen at a sac-like structure called the cisterna chyli.
- Ascends
through the aortic opening of the diaphragm.
- Travels
upward through the posterior mediastinum into the neck.
3. Path and Relations
- In the
thorax (posterior mediastinum):
- Lies between
the azygos vein (right) and descending aorta (left)
- Behind:
esophagus
- In front
of: vertebral column
- In the
neck:
- Arches
laterally at C7 vertebra
- Crosses left
side behind carotid sheath
4. Termination
- Ends at
the junction of:
- Left
subclavian vein
- Left
internal jugular vein
- This point
is called the left venous angle
5. Tributaries
The thoracic duct receives lymph from:
Below the diaphragm:
- Both lower
limbs
- Pelvis
- Abdomen (via cisterna
chyli)
Above the diaphragm (left
side):
- Left side
of thorax
- Left upper
limb
- Left half
of head and neck
- Left
bronchomediastinal trunk
6. Function
- Drains
lymph from ¾ of the body into the bloodstream.
- Helps in:
- Returning
excess tissue fluid to the venous system
- Transport
of fat from intestines (via chyle)
- Maintaining
fluid balance in the body
- Immunity, by
carrying lymphocytes
Tags
ANATOMY