Axillary Lymph Nodes

Generality

Axillary lymph nodes are the lymph nodes that reside in the armpit.

Between 20 and 40 units, the axillary lymph nodes can be divided into 6 groups: the pectoral group, the subscapular group, the lateral group, the central group, the apical group and the infraclavicular group.

The axillary lymph nodes have the important task of draining and filtering the lymph coming from the upper limbs, from the part of the trunk that goes from the umbilicus to the beginning of the neck and, finally, from the back that is above the iliac crests.

Short review of what the lymph nodes are

Lymph nodes are small ovoid organs of the lymphatic system, having a very important immune role ; in fact, they act as collection points for part of the B and T lymphocytes (cells of the immune system), in order to intercept and destroy any germs, foreign substances and / or neoplastic cells circulating in the lymph (the lymph is the fluid similar to the plasma, which flows along the lymphatic vessels and receives the waste substances present in the tissues).

Acting similarly to purifiers, lymph nodes are often referred to as biological filters.

What are Axillary Lymph Nodes?

Axillary lymph nodes are the lymph nodes that reside in the armpit ; the axilla is the anatomical area of ​​the human body located below the shoulder joint, where the lateral edge of the thorax meets the proximal portion of the arm.

Anatomy

The axillary lymph nodes are between 20 and 40 units and, according to their location, they are distinguishable in 6 groups, which are:

• The pectoral group (or anterior group ) of axillary lymph nodes;
• The subscapular group (or posterior group ) of the axillary lymph nodes;
• The lateral group of axillary lymph nodes;
• The central group of axillary lymph nodes;
• The apical group of axillary lymph nodes;
• The infraclavicular group (or sub- clavicular group or deltopectoral group ) of the axillary lymph nodes.

Breast group (or front group)

The pectoral group of axillary lymph nodes includes 4-5 medium-large lymph node units, which take place along the inferior margin of the pectoralis small muscle and immediately behind the pectoralis major muscle .

The axillary lymph nodes of the pectoral group receive lymph from the lymphatic vessels coming from the lateral quadrants of the breasts, from the superficial lymphatic vessels of the thorax and, finally, from the lymphatic vessels of the supra-umbilical abdominal portion (ie which is above the navel); then they discharge the lymph that they received, mainly, in the lymph nodes of the central group.

Important note: axillary lymph nodes are even anatomical elements

Axillary lymph nodes are even elements of the human body; in practical terms, this means that, for each side of the trunk, there are all the different lymph node groups mentioned above.

The concept of even distribution of axillary lymph nodes is important to explain that lymphatic drainage of the structures on the same side rests on the lymph node groups of one side of the body; for example, the axillary lymph nodes of the right pectoral group receive the lymph coming from the right breast, from the right half of the thorax and from the right supra-umbilical abdominal portion, and discharge the same into the lymph nodes of the central group of the right half of the trunk.

Subscapularis group (or back group)

The subscapular group of axillary lymph nodes includes 6-7 medium-sized lymph node units, which are distributed in front of the subscapularis muscle, in a lower position than the scapula .

The axillary lymph nodes of the subscapular group receive lymph from the superficial lymphatic vessels of the neck and upper back ; therefore, like the lymph node units of the pectoral group, they discharge the lymph received in the axillary lymph nodes of the central group.

Lateral group

The lateral group of axillary lymph nodes comprises between 4 and 6 lymph node units of intermediate size, which reside in a postero-medial position with respect to the axillary vein and in a lateral position with respect to the group of pectoral muscles .

The axillary lymph nodes of the lateral group receive the lymph from the lymphatic vessels coming from the arm (except for those superficial lymphatic vessels of the arm that run in the lateral region of the latter); therefore, like the axillary lymph nodes of the two groups described above, they discharge the lymph received in the axillary lymph nodes of the central group.

Central group

The well-known central group of axillary lymph nodes includes 3-4 medium-large lymph node units, which take place exactly at the center of the axilla, immersed in the adipose tissue typical of the axillary region.

As stated in the previous sections, the axillary lymph nodes of the central group receive the lymph that has passed through the axillary lymph nodes of the pectoral, subscapular and lateral groups; therefore, they discharge what they received in the axillary lymph nodes of the apical group.

Apical group

The apical group of axillary lymph nodes comprises between 4 and 6 lymph node units of intermediate size, which are distributed on the highest part of the axilla, precisely on the lateral edge of the first rib, behind and above the small pectoral muscle, and with an orientation in the direction of the axillary vein.

The axillary lymph nodes of the apical group receive the lymph previously passed through the axillary lymph nodes of the central group, for the lymph nodes of the infraclavicular group (discussed in the next section), for the lymphatic vessels associated with the cephalic vein and, finally, for the lymphatic vessels coming from the upper peripheral portion of the breast ; therefore, they pour their lymph content, mainly, into the subclavian lymph trunk, into the right lymphatic duct and into the deep cervical lymph nodes.

Infraclavicular group (or subclavicular or deltopectoral)

The infraclavicular group of axillary lymph nodes represents a separate category, since the 6-12 constituent lymph node units reside outside the anatomical region of the axilla; to be precise, they take place in the groove between the deltoid muscle and the pectoralis major muscle, just below the clavicle .

The axillary lymph nodes of the infraclavicular group receive the lymph from the lymphatic vessels coming from the lateral portions of the hand, forearm and arm ; therefore, they discharge their lymph content mainly in the axillary lymph nodes of the apical group.

Short explanation

According to some anatomical visions, the lymph nodes of the infraclavicular group would not belong to the category of axillary lymph nodes. This explains why, in this article, they are treated last (logically, it would have been better to describe them before the axillary lymph nodes of the apical group) and because different texts of anatomy, in treating axillary lymph nodes, speak only of 5 groups (the pectoral, posterior, lateral, central and apical).

Function

The axillary lymph nodes have the vital function of draining and filtering the lymph coming from the upper limbs, from the part of the trunk that goes from the umbilicus to the beginning of the neck and, finally, from the back that is above the iliac crests . Going into more detail, the axillary lymph nodes drain and filter the sap that comes from:

• The arm, the forearm and the hand;
• The lateral quadrants of the breast;
• The upper peripheral portion of the breast;
• The most superficial portions of the chest;
• The supra-umbilical abdominal region;
• The back starting from the iliac crests up to the neck.

diseases

Axillary lymph nodes are elements of considerable clinical relevance, as they are the subject of an enlargement process ( axillary lymphadenopathy ) when clinical conditions such as:

• Infectious diseases involving the upper respiratory tract (eg: flu, cold and pharyngitis );
• Measles and mononucleosis ;
• Skin infections localized in the upper part of the body, especially if combined with skin wounds;
• AIDS ;
• Otitis ;
• Malignant tumors located in the trunk, such as breast cancer or lung cancer ;
• Metastases deriving from the aforementioned typology of malignant tumors.

Axillary lymph node enlargement in the presence of breast cancer

Responsible for more or less intense axillary pain, axillary lymphadenopathy is one of the most typical signs of breast cancer, consequently being a crucial element in the formulation of the final diagnosis.

In the presence of the dreaded neoplasm, the systematic occurrence of enlargement of axillary lymph nodes is mainly due to the fact that as much as 75% of the lymph circulating in the breasts flows into the pectoral and apical groups of the axillary lymph nodes.

Some interesting facts about the diagnostic role of axillary lymph nodes in the presence of breast cancer

Laboratory analysis of some cells from axillary lymph nodes allows physicians to establish the stage (or staging ) of the aforementioned neoplasm.

The axillary lymph node withdrawal procedure consists of a surgical operation known as axillary dissection or axillary lymph node dissection ; the latter is useful not only in the diagnostic field, but also in the treatment phase.