isthmus
Meaning of isthmus: An isthmus is a narrow band of tissue connecting two larger anatomical structures, a term applied across several different organs.
Definition of isthmus
An isthmus is a narrow segment of tissue that connects two larger structures within the body. The term is used to describe this kind of narrow connection in several different organs, including the isthmus of the thyroid gland, which joins its two lobes, and the isthmus of the uterus, a narrow segment between the body of the uterus and the cervix.
The term is also used outside the reproductive and endocrine systems, such as the isthmus of the fauces, the narrow opening connecting the mouth to the throat, illustrating that the word describes a general anatomical relationship rather than referring to one single structure.
Because an isthmus is often a comparatively narrow and sometimes more fragile connection between larger structures, it can be a site of particular clinical relevance, such as during surgery near the thyroid isthmus or in evaluating the uterine isthmus during pregnancy.
Used in a sentence
Surgical dissection carefully identified the thyroid isthmus before the gland was removed.
Good to know
The word isthmus always describes the same general relationship, a narrow connection between two larger structures, so the specific organ under discussion must be clear from context.
Word origin
Where “isthmus” comes from
Formed from Greek isthmos, meaning neck or narrow passage, originally describing a narrow strip of land connecting two larger landmasses.