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Isthmus of uterine tube: anatomy, location and function

The isthmus is the narrow, thick-walled medial third of the uterine tube. Its thick muscle helps move sperm towards the ampulla and the embryo towards the uterus.

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Highlighted in the model: Isthmus of uterine tube. Click any part to read about it, or switch off “Highlight topic” to see the whole body. Use Male / Female to switch bodies. 3D data: BodyParts3D, © The Database Center for Life Science; knee ligaments, menisci, tonsils, palate and parotid glands from the Human Reference Atlas Visible Human Male model and female parts from its Visible Human Female model (HuBMAP / NIH); lung lobes built from the BodyParts3D chest; all CC BY 4.0; meshes simplified and recoloured. The female body shares the male skeleton, muscles and organs except its pelvis, reproductive organs, breasts, bladder, urethra and skin.

Isthmus of uterine tube at a glance

What it is
The isthmus is the narrow, thick-walled medial third of the uterine tube.
Location
It lies next to the uterus, between the ampulla and the part of the tube inside the uterine wall.
Function
Its thick muscle helps move sperm towards the ampulla and the embryo towards the uterus.
Body system
Reproductive · paired (left and right) · female body
FMA ID
FMA18494 (Foundational Model of Anatomy)

Key facts

  • Medially it joins the intramural part of the tube, which passes through the uterine wall to open into the uterine cavity.

Clinical relevance

Tubal sterilisation (clips or rings) is usually applied to the isthmus.

Structures next to the isthmus of uterine tube

The nearest named structures in the 3D model, measured from the centre of each part:

References

  1. Foundational Model of Anatomy: Isthmus of uterine tube (FMA18494). EMBL-EBI Ontology Lookup Service.
  2. OpenStax. Anatomy and Physiology 2e, §27.2 Anatomy and Physiology of the Ovarian Reproductive System. Rice University, 2022.
  3. Mitsuhashi N. et al. (2009). BodyParts3D: 3D structure database for anatomical concepts. Nucleic Acids Research 37, D782–D785. Data © The Database Center for Life Science, CC BY 4.0.
  4. Browne K., Schlehlein H. 3D Reference Organ Set for United, Female (Visible Human Female). Human Reference Atlas 3D Reference Object Library, HuBMAP / NIH. Data from the NLM Visible Human Project. CC BY 4.0.

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