Lymphatic System

This is the first time we have mentioned the lymphatic
system so we need to consider an overview of the system to
understand how it works. Without going into a detailed description,
the following diagram shows the general makeup of a lymph node
and its afferent and efferent vessels. The lymphatic system is
part of the vascular system but it is very special in its
ability to take in larger particles than the vascular system
(i.e., bacteria, cancer cells, carbon). It is also part of
the immune system of our body and, therefore, serves as a
first line of protection against foreign bodies. This protection is
subserved by cells of the immune system.

In general, lymph is picked up peripherally from
blind-ended vessels. These vessels are the afferents that lead
to the lymph nodes. When the nodes are reached, the lymph
percolates through a reticulum and is exposed to immune cells. The
lymph then leaves the node by way of efferent vessels which
may lead to another node or group of nodes, and re-exposed
to immune cells. The efferent vessels from the last group of
nodes then become larger and are called lymph trunks. The
lymph trunks finally join to form lymph ducts. There are two
lymph ducts and they are located in the neck. On the
right side, the jugular and subclavian trunks join to form the
right lymphatic duct. On the left side, the jugular and subclavian
trunks empty into the thoracic duct. The two ducts then enter
the venous system at the junction of the jugular vein and
subclavian vein which become the brachiocephalic veins.

typical lymph node

Axillary Lymph Nodes

The last of the axillary contents are the axillary lymph nodes.
Lymph from the upper limb, shoulder and scapular regions, pectoral region
(including the mammary gland) and upper abdomen drain through the axillary
nodes. There are some 15 to 20 nodes usually arranged into to five groups. The groups consist of:
  • A pectoral (anterior)
  • L lateral
  • P posterior
  • C central
  • Ap apical
axillary lymph nodes The efferent lymph vessels from the right group of axillary nodes finally forms into the subclavian lymphatic trunk which joins the jugular trunk to form the right lymphatic duct which empties into the venous system at the junction of the jugular and subclavian veins.
On the left side the subclavian lymphatic trunk empties into the thoracic duct and then into the venous system at the junction of the jugular and subclavian veins.
Brachial Plexus Summary List

Table of Contents for Upper Limb & Back