D2I2.
structural

Schatzki ring

A Schatzki ring or Schatzki–Gary ring is a narrowing of the lower that can cause difficulty swallowing (dysphagia). The narrowing is caused by a ring of or muscular tissue. A Schatzki ring is a specific type of " ring", and Schatzki rings are further subdivided into those above the esophagus/stomach junction, and those found at the squamocolumnar junction in the lower esophagus.

Underlined words are explained — tap any of them.

Plain-language summary adapted from Wikipedia. Not medical advice.