Lymphatic Vessels

LYMPHATIC VESSELS

Lymphatic vessels transport lymph from tissues toward the heart. They are thin-walled and larger than lymphatic capillaries.

There are two main types of lymphatic vessels:

Types of Lymphatic Vessels

These vessels:

• Are closed at one end
• Contain valves to prevent backflow
• Drain excess interstitial fluid into venous circulation

The walls of lymphatic vessels consist of endothelium and smooth muscle. Movement of lymph is supported by:

• Skeletal muscle contraction
• Pulsation of nearby arteries
• Normal body movements

LYMPH TRUNKS

Lymph from lymphatic vessels passes through lymph nodes and then combines to form lymph trunks. These trunks are large collecting channels.

Major Lymph Trunks

LYMPH DUCTS

Lymph trunks finally drain into two major lymphatic ducts.

Types of Lymphatic Ducts

• Thoracic duct (Left lymphatic duct)
• Right lymphatic duct

Drainage of Lymphatic Ducts

Thoracic Duct (Left Lymphatic Duct)

The thoracic duct is the largest lymphatic duct, measuring about 38–45 cm in length. It begins in the abdomen as a dilated sac called cisterna chyli.

The cisterna chyli receives lymph from:

• Left lumbar trunk
• Right lumbar trunk
• Intestinal trunk

In the neck region, the thoracic duct also receives lymph from:

• Left jugular trunk
• Left subclavian trunk
• Left broncho-mediastinal trunk

The thoracic duct drains lymph from the entire left side of the body and lower half of the body, which is why it is called the left lymphatic duct.

Right Lymphatic Duct

The right lymphatic duct is short, measuring about 1–2 cm.

It receives lymph from:

• Right jugular trunk
• Right subclavian trunk
• Right bronchomediastinal trunk

It drains lymph from the right side of the head, neck, thorax, and right upper limb into the right subclavian and internal jugular veins.