Ureter
The ureter or ureters are tubules that arise from the renal pelvis and measure approximately 25cm. They descend through the posterior wall of the abdomen and are retroperitoneal. They have different routes and portions: lumbar, iliac, pelvic, and bladder; They present different thickenings and widenings in these portions, which are important in cases of lithiasis. They descend in a straight line to the level of the iliopsoas muscle, then are traversed in their middle portion by the gonadal arteries. There will be a series of arteries that will come from the internal iliac artery, the gonadal arteries or the renal arteries and will form a true plexus around the ureter, therefore it is well irrigated, and after passing through the lumbar region, will traverse the iliac vessels in a relationship as follows:
Right ureter crosses the external iliac left ureter crosses the common iliac
When it crosses the iliac vessels, it narrows the ureter, which is important in the case of lithiasis, since it is where they occur the most. The last portion of the ureters is vesical, leading to the posterior inferior aspect of the bladder.
Embryological origin
It comes from the endoderm of the primitive allantois that has been ascending to form this excretory duct, formed by:
- Kidney chalices.
- Urine bladder.
Structure
The ureter is a muscular-membranous tube, formed by three muscular layers and an adventitia.
Muscular Layer
Its muscle fibers are arranged intertwined in three layers that allow peristalsis of the ureter from the kidneys to the bladder.
- Internal longitudinal layer. are set of muscle fibers that move.
- Intermediate muscle layer, whose fibers are circular and are arranged forming powerful rings as a sphincter.
- External longitudinal layer formed at the expense of fibers.
Adventitia layer
Formed by connective tissue that covers the ureter and isolates it from other tissues.
Narrowings
It has three narrowings of great clinical importance, since kidney stones lodge in them when descending.
- Between the renal pelvis and the ureter
- Crossing the outer iliac artery
- By crossing the bladder wall