Ureter

Ureter
The ureters (labeled 4) are tubes that carry urine and connect the kidneys to the bladder.
Details
Precursor	Ureteric bud
System	Urinary system
Artery	Superior vesical artery, vaginal artery, ureteral branches of renal artery
Nerve	Ureteric plexus
Identifiers
Latin	ureter
MeSH	D014513
TA98	A08.2.01.001
TA2	3394
FMA	9704
Anatomical terminology [edit on Wikidata]

The ureters are tubes composed of smooth muscle that transport urine from the kidneys to the urinary bladder. In an adult human, the ureters typically measure 20 to 30 centimeters in length and about 3 to 4 millimeters in diameter. They are lined with urothelial cells, a form of transitional epithelium, and feature an extra layer of smooth muscle in the lower third to aid in peristalsis. The ureters can be affected by a number of diseases, including urinary tract infections and kidney stone. Stenosis is when a ureter is narrowed, due to for example chronic inflammation. Congenital abnormalities that affect the ureters can include the development of two ureters on the same side or abnormally placed ureters. Additionally, reflux of urine from the bladder back up the ureters is a condition commonly seen in children.

The ureters have been identified for at least two thousand years, with the word "ureter" stemming from the stem uro- relating to urinating and seen in written records since at least the time of Hippocrates. It is, however, only since the 1500s that the term "ureter" has been consistently used to refer to the modern structure, and only since the development of medical imaging in the 1900s that techniques such as X-ray, CT, and ultrasound have been able to view the ureters. The ureters are also seen from the inside using a flexible camera, called ureteroscopy, which was first described in 1964.