axillary
Meaning of axillary: Belonging to the armpit, a small hollow crowded with the nerves, vessels and lymph nodes that serve the entire arm.
Definition of axillary
Axillary means belonging to or situated in the axilla, the hollow under the arm known in everyday speech as the armpit. The word attaches to the structures crossing that space: the axillary artery and vein, the nerves heading into the arm, and the lymph nodes collecting fluid from the arm, the chest wall and the breast.
What passes through the armpit?
Far more than its size suggests. The artery supplying the whole arm crosses it, with the vein returning blood alongside, and the bundle of nerves running from the neck to the hand travels with them. Around those sits a cluster of lymph nodes, usually a few dozen, and a tail of breast tissue reaches into the space. The whole arrangement is wrapped in a sleeve of tissue that lets it slide as the shoulder moves, which is why raising the arm changes what can be felt there and why examination is done with the arm relaxed.
Why do the lymph nodes matter so much?
Because they drain the breast and chest wall as well as the arm, and cells travelling in lymph reach them early. Whether an axillary lymph node contains tumor is among the strongest indicators of how far a breast cancer has progressed, and the answer shapes the treatment that follows. Nodes here also swell with ordinary causes: an infected cut on the hand, a cat scratch, a skin condition of the arm, or an illness affecting the immune system as a whole. A firm node found in the armpit is therefore a finding that needs explaining rather than a diagnosis on its own.
How is the armpit examined and treated?
| Procedure | What it involves | Main consequence |
|---|---|---|
| Sentinel node biopsy | Removes the first node or two receiving drainage | Leaves the rest of the field undisturbed |
| Axillary dissection | Removes the node-bearing tissue in levels | Higher rate of lasting arm swelling |
| Ultrasound with needle sampling | Images the nodes and samples suspicious ones | No incision required |
| Axillary temperature | Thermometer held in the closed armpit | Reads lower than the true core temperature |
The shift away from routine axillary lymph node dissection toward sentinel lymph node sampling was driven by lymphedema, a persistent swelling of the arm that follows when drainage channels are removed and rarely settles completely.
Also known as
Used in a sentence
The axillary nodes were clinically normal on examination.
Good to know
Axillary lymph nodes drain the breast and chest wall as well as the arm, so enlargement there is assessed against all three, and removing them raises the risk of lasting swelling in that arm.
Word origin
Where “axillary” comes from
Axillary comes from the Latin axilla, meaning armpit, a diminutive of ala, a wing.