science

Urachus

Urachus is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Urachus rather than just read about it. In short: The urachus forms from the distal end of the allantois in the embryo, and develops into a closed cord between the base of the bladder, and the navel. It drains the bladder of the fetus that joins and runs within the umbilical cord.

Key takeaways

Urachus belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Urachus to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Urachus from memory before moving on to harder problems.

Reference excerpt

The urachus forms from the distal end of the allantois in the embryo, and develops into a closed cord between the base of the bladder, and the navel. It drains the bladder of the fetus that joins and runs within the umbilical cord. The fibrous remnant lies in the space of Retzius, between the transverse fascia anteriorly and the peritoneum posteriorly. At birth, the urachus develops into the median umbilical ligament.

Development The part of the urogenital sinus related to the bladder and urethra absorbs the ends of the Wolffian ducts and the associated ends of the renal diverticula. This gives rise to the trigone of the bladder and part of the prostatic urethra. The remainder of this part of the urogenital sinus forms the body of the bladder and part of the prostatic urethra. The apex of the bladder stretches and is connected to the umbilicus as a narrow canal. This canal is initially open, but later closes as the urachus goes on to definitively form the median umbilical ligament.

Clinical significance Failure of the inside of the urachus to be filled in leaves the urachus open. The telltale sign is leakage of urine through the umbilicus. This is often managed surgically. There are four anatomical causes:

Urachal cyst: there is no longer a connection between the bladder and the umbilicus, however a fluid filled cavity with uroepithelium lining persists between these two structures. Urachal fistula: there is free communication between the bladder and umbilicus Urachal diverticulum (vesicourachal diverticulum): the bladder exhibits outpouching Urachal sinus: the pouch opens toward the umbilicus The urachus is also subject to neoplasia. Urachal adenocarcinoma is histologically similar to adenocarcinoma of the bowel. Rarely, urachus carcinomas can metastasise to other regions of the body, including pelvic bones and the lung. One urachal mass has been reported that was found to be a manifestation of IgG4-related disease.

Additional images

References This article incorporates text in the public domain from page 1213 of the 20th edition of Gray's Anatomy (1918)

External links Swiss embryology (from UL, UB, and UF) turinary/patholurinary07 "Persistent urachus" at Moorabbin Veterinary Hospital "Patent Urachus Repair" at Penn Medicine

Illustrations

Worked examples

Example 1 — a first encounter with Urachus

Start with the simplest possible case. Write down what Urachus claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Urachus before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Urachus ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Urachus

In research: Urachus appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Urachus in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Urachus is common in secondary-school and first-year university syllabi. It links to neighbouring topics Embryology of urogenital system, so understanding it makes those chapters shorter.
In everyday life: Look for Urachus outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Urachus in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Urachus means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Urachus out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Urachus in simple terms?

Why does Urachus matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Urachus?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Urachus.