also: ないくう
noun
Anatomical term for the interior space of a tubular structure, such as a blood vessel or intestine.
血管の内腔が狭くなると、血流が悪くなる。
When the lumen of a blood vessel narrows, blood flow worsens.
内視鏡で腸の内腔を観察した
We observed the intestinal lumen with an endoscope.
A general term for a cavity or hollow space in the body; 内腔 specifically refers to the interior space within a tubular organ.
Composed of 内 (inside) and 腔 (cavity), directly corresponding to the anatomical concept of a lumen.