What Is the Axilla?
The axilla, commonly known as the underarm, is the area between the upper arm and the side of the chest. While it may seem like a small hollow beneath the shoulder, it is an important anatomical region containing lymph nodes, blood vessels, nerves, and fatty tissue.
The axilla acts as a bridge between the arm and the body. Major blood vessels and nerves pass through this space to supply the arm with movement, strength, and sensation.
The Axilliary (Underarm)
Anatomy and Function
The axilla has a pyramid-like shape, with muscles forming its front and back walls. Within this space are several vital structures:
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These filter lymphatic fluid from the arm, chest wall, and breast. They help the body fight infection and are especially important in breast health assessment.
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The axillary artery and vein supply blood to and from the upper limb.
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Important nerves of the brachial plexus pass through the axilla, controlling arm and hand movement and sensation
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This cushions and protects the underlying structures.
The Axilla in Breast Health
In breast cancer care, the axilla is carefully evaluated because cancer cells may spread first to the lymph nodes in this region. Assessment may include physical examination, ultrasound imaging, and sometimes needle biopsy.
If surgery for breast cancer is required, procedures such as sentinel lymph node biopsy may be performed to determine whether cancer has spread. Modern approaches aim to minimise disruption to the axilla to reduce complications such as lymphoedema (arm swelling).
When to Seek Assessment
Underarm swelling or lumps are commonly caused by infection or benign conditions. However, any persistent lump, enlargement, or discomfort should be assessed promptly to ensure accurate diagnosis and appropriate management.