tracheal carina
Meaning of tracheal carina: A landmark as much as a structure: tube depth, biopsy sites and staging in the chest are all reckoned from this one ridge.
Definition of tracheal carina
The tracheal carina is the cartilage ridge at the lower end of the windpipe, where it splits into the two main bronchi. It serves as the reference point for airway work: breathing tubes are positioned by their distance above it, bronchoscopy begins by inspecting it, and chest imaging uses the angle it makes to judge whether structures beneath it are enlarged.
Why is it used as a landmark?
Because it is unmistakable and it does not move much. Every other feature of the airway looks broadly like its neighbors, while this ridge is a single sharp division visible the moment a bronchoscope reaches it, and it is equally clear on a chest film or scan. A breathing tube is positioned by measuring its tip against this point, far enough above to stay clear of the branch and far enough below the vocal cords to remain secure. Depths quoted for suction catheters and for airway measurements are given from here. In the same way, distances reported when a lesion is found are stated as how far above or below it the abnormality sits.
What does its appearance reveal?
| Appearance | What it points to |
|---|---|
| Thin, sharp, moving with each breath | Normal |
| Broadened and blunted | Enlarged lymph nodes pushing from below |
| Rigid and distorted | Tumor growing into the airway wall |
| Splayed wide on imaging | A mass beneath it or an enlarged left atrium |
What sits immediately beneath it?
A crowded space. Lymph nodes in the gap below the ridge collect drainage from both lungs, which makes them one of the first places disease from either side turns up and a routine target for sampling when lung cancer is being staged. An ultrasound probe on the tip of a bronchoscope can see through the airway wall into that space and guide a needle into a node without any incision. Behind and below lie the esophagus and the left upper chamber of the heart, close enough that a chamber enlarged by valve disease widens the angle between the bronchi on a chest film. The ridge marks the end of the windpipe, and the older anatomical name for the same structure is the carina of trachea.
Also known as
Used in a sentence
The endotracheal tube tip lay above the tracheal carina on the chest film.
Good to know
The lymph nodes lying immediately beneath the carina drain both lungs, so their enlargement widens the angle between the main bronchi, a change looked for when lung cancer is staged.
Word origin
Where “tracheal carina” comes from
Carina is the Latin word for the keel of a ship, which the ridge resembles when it is viewed from above.