also: ないくう
Anatomical term for the interior space of a tubular structure, such as a blood vessel or intestine.
When the lumen of a blood vessel narrows, blood flow worsens.
We observed the intestinal lumen with an endoscope.
Standard kanji form for this anatomical term.
Alternate reading; less common in modern medical usage.
Composed of 内 (inside) and 腔 (cavity), directly corresponding to the anatomical concept of a lumen.