Thoracic duct  Lymph duct: • A lymph duct is a great lymphatic vessel that empties lymph into one of the subclavian veins. • There are two lymph ducts in the body the right lymphatic duct and the thoracic duct. • The right lymphatic duct drains lymph from the right upper limb, right side of thorax and right halves of head and neck. • The thoracic duct drains lymph into the circulatory system at the left brachiocephalic vein between the left subclavian and left internal jugular veins.  Thoracic duct: • In human anatomy, the thoracic duct is the larger of the two lymph ducts of the lymphatic system. It is also known as the left lymphatic duct, alimentary duct, chyliferous duct, and Van Hoorne's canal. • The thoracic duct is the largest lymphatic vessel in the human body. Around 75% of the lymph from the entire body passes through the thoracic duct. • The other duct is the right lymphatic duct. The thoracic duct carries chyle, a liquid containing lymph and emulsified fats, rather than pure lymph. • It also collects most of the lymph in the body other than from the right thorax, arm, head, and neck (which are drained by the right lymphatic duct).  Structure: • In adults, the thoracic duct is typically 38 – 45 cm in length and has an average diameter of about 5 mm. • The vessel usually starts from the level of the twelfth thoracic vertebra (T12) and extends to the root of the neck. • It drains into the systemic (blood) circulation at the angle of the left subclavian and internal jugular veins as a single trunk, at the commencement of the brachiocephalic vein • The thoracic duct originates in the abdomen from the confluence of the right and left lumbar trunks and the intestinal trunk, forming a significant pathway upward called the cisterna chyli. • It traverses the diaphragm at the aortic aperture, and ascends the superior and posterior mediastinum between the descending thoracic aorta (to its left) and the azygos vein (to its right). • The duct extends vertically in the chest and curves posteriorly to the left carotid artery and left internal jugular vein. • At the T5 vertebral level it crosses the midline to the left side. It ascends further to terminate into the systemic (blood) circulation at the venous angle of the left subclavian and internal jugular veins i.e. the commencement of the brachiocephalic vein, below the clavicle, near the shoulders.  Area of drainage: • The thoracic duct drains the lymph from all the parts of the body with the exception of  Right side of the head and neck  Right side of the chest wall  Right lung  Right side of the heart  Right surface of the liver.  The right upper quadrant of the body that is drained by the right lymphatic duct.  Function: • The thoracic duct collects most of the lymph in the body other than from the right thorax, arm, head, and neck. • The lymph transport, in the thoracic duct, is mainly caused by the action of breathing, aided by the duct's smooth muscle

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Thoracic duct
 Lymph duct:
 A lymph duct is a great lymphatic vessel that empties lymph into one of the subclavian
veins.
 There are two lymph ducts in the body the right lymphatic duct and the thoracic duct.
 The right lymphatic duct drains lymph from the right upper limb, right side
of thorax and right halves of head and neck.
 The thoracic duct drains lymph into the circulatory system at the left brachiocephalic
vein between the left subclavian and left internal jugular veins.
 Thoracic duct:
 In human anatomy, the thoracic duct is the larger of the two lymph ducts of
the lymphatic system. It is also known as the left lymphatic duct, alimentary
duct, chyliferous duct, and Van Hoorne's canal.
 The thoracic duct is the largest lymphatic vessel in the human body. Around 75% of the
lymph from the entire body passes through the thoracic duct.
 The other duct is the right lymphatic duct. The thoracic duct carries chyle, a liquid
containing lymph and emulsified fats, rather than pure lymph.
 It also collects most of the lymph in the body other than from the right thorax, arm,
head, and neck (which are drained by the right lymphatic duct).

2. Page 2 of 3
 Structure:
 In adults, the thoracic duct is typically 38 – 45 cm in length and has an average diameter
of about 5 mm.
 The vessel usually starts from the level of the twelfth thoracic vertebra (T12) and extends
to the root of the neck.
 It drains into the systemic (blood) circulation at the angle of the left subclavian and
internal jugular veins as a single trunk, at the commencement of the brachiocephalic vein
 The thoracic duct originates in the abdomen from the confluence of the right and
left lumbar trunks and the intestinal trunk, forming a significant pathway upward called
the cisterna chyli.
 It traverses the diaphragm at the aortic aperture, and ascends the superior and posterior
mediastinum between the descending thoracic aorta (to its left) and the azygos vein (to its
right).
 The duct extends vertically in the chest and curves posteriorly to the left carotid
artery and left internal jugular vein.
 At the T5 vertebral level it crosses the midline to the left side. It ascends further to
terminate into the systemic (blood) circulation at the venous angle of the left subclavian
and internal jugular veins i.e. the commencement of the brachiocephalic vein, below
the clavicle, near the shoulders.

3. Page 3 of 3
 Area of drainage:
 The thoracic duct drains the lymph from all the parts of the body with the exception of
 Right side of the head and neck
 Right side of the chest wall
 Right lung
 Right side of the heart
 Right surface of the liver.
 The right upper quadrant of the body that is drained by the right lymphatic duct.
 Function:
 The thoracic duct collects most of the lymph in the body other than from the right thorax,
arm, head, and neck.
 The lymph transport, in the thoracic duct, is mainly caused by the action of breathing,
aided by the duct's smooth muscle and by internal valves which prevent the lymph from
flowing back down again.
 There are also two valves at the junction of the duct with the left subclavian vein, to
prevent the flow of venous blood into the duct.
 In adults, the thoracic duct transports up to 4 L of lymph per day.