Macroscopic structure and parts
Anatomically, the ureter is a hollow muscular tube about 30–35 cm in length. Its main task is the uninterrupted delivery of urine from the kidneys to the reservoir (the urinary bladder).
Topographically, the organ is usually divided into two main parts:
- Abdominal part (pars abdominalis) — the upper segment, passing in the retroperitoneal space.
- Pelvic part (pars pelvina) — the lower segment, located in the pelvic cavity.
As urine moves along, the muscular elements of the organ generate peristaltic waves, allowing fluid to actively enter the urinary bladder regardless of body position.
Physiological constrictions of the ureter
The lumen of the organ is uneven. Along the course of the tube, three characteristic physiological constrictions are distinguished, which are of immense clinical significance (for example, calculi in urolithiasis most frequently get trapped in them):
- Ureteropelvic junction — the site of direct transition of the renal pelvis (pelvis renalis) into the ureter proper (ureter).
- Marginal constriction — the zone where the ureter crosses the major iliac vessels during the transition from the abdominal cavity to the pelvic cavity.
- Intramural part — at the site where the organ opens into the wall of the urinary bladder.
Histological structure of the wall
The ureter wall is well adapted to stretching and active contractions. It consists of three distinct layers:
- Mucous membrane (tunica mucosa) — the inner layer lining the lumen of the organ.
- Muscular coat (tunica muscularis) — the middle layer formed by smooth muscle cells. It consists of longitudinal and circular bundles that provide peristalsis.
- Adventitia (tunica adventitia) — the outer connective tissue sheath fixing the organ in the surrounding tissues.
Topographic features in males
In the male pelvis, the path of the ureter has several specific crossings with the reproductive system organs:
- Just before entering the wall of the urinary bladder, it crosses the ductus deferens. At the same time, the duct is located medial to the ureter.
- The site where the ureter opens into the urinary bladder is projected below the floor of the rectovesical pouch of the peritoneum.
- The entry point anatomically corresponds to the apex of the seminal vesicle.
Topographic features in females
In females, the syntopy (spatial relation with neighboring structures) of the ureter is particularly complex and critically important for operating surgeons and gynecologists:
- First, the ureter crosses the origin of the uterine artery, lying more superficial to it.
- Then it courses medially, downward and forward, passing within the thickness of the parametrial tissue (parametrium).
- At the level of the cervix uteri, it crosses the uterine artery again, but here the ureter is already located inferior to the vessel.
Clinical significance: The close and complex intertwining of the ureter with the uterine artery creates a high risk of its accidental injury (ligation or transection) during gynecological surgeries, such as hysterectomy.
Briefly: answers to topical questions
What type of epithelium lines the mucous membrane of the ureter?
The mucous membrane of the ureter is lined with stratified transitional epithelium (urothelium) facing the lumen of the organ. A distinctive histological feature of this epithelium is that the nuclei of its superficial cells are round in shape. Directly beneath the epithelial layer lies the lamina propria of the mucous membrane (lamina propria). Meanwhile, the muscularis mucosae is entirely absent in the ureter.
Which arteries supply blood to the abdominal part of the ureter?
Blood supply to the abdominal part of the ureter is provided by the ureteric branches of the renal arteries (rr. ureterici), as well as small branches of the common iliac arteries. The renal artery gives off ureteric branches before the renal hilum and from its posterior branch.
How is the ureter positioned relative to the peritoneum?
Relative to the peritoneum, the ureter is located retroperitoneally.
- Abdominal part (pars abdominalis) — located retroperitoneally in the retroperitoneal space of the posterior abdominal wall.
- Pelvic part (pars pelvina) — lies in the subperitoneal tissue of the lesser pelvis (in the subperitoneal space).
Throughout its length, the ureters are surrounded by periureteric adipose tissue and possess their own fascial sheath.
To which lymph nodes does lymph drain from the pelvic part of the ureter?
Lymph from the pelvic part of the ureter drains into the iliac lymph nodes.
Which autonomic plexuses innervate the ureter?
The ureter is innervated by branches of several autonomic plexuses.
- Superior hypogastric plexus — participates in the innervation of the pelvic parts of the organ.
- Inferior hypogastric plexus — also provides innervation to the pelvic parts of the ureter.
In addition, in the lower part of the ureter, parasympathetic innervation is present, originating from the pelvic splanchnic nerves (nn. splanchnici pelvini).
Remembering the three constrictions is easy using the formula "Start — Crossing — Finish": transition of the pelvis to the ureter (start), crossing of the iliac vessels (crossing), and entry into the urinary bladder (finish).
Class and exam questions
What is the average length of the ureter in an adult?
Normally, the length of the ureter is about 30–35 centimeters.
What layers make up the muscular tunic of the ureter?
The muscular coat (tunica muscularis) is formed by longitudinal and circular layers of smooth muscle.
How is the ureter positioned relative to the uterine artery at the cervix of the uterus?
At the level of the cervix uteri, the ureter crosses the uterine artery, lying inferior to it (below the artery).
Where is the entrance of the ureter into the urinary bladder projected in men?
It is located below the floor of the rectovesical pouch and corresponds to the level of the apex of the seminal vesicle.
What else to study on this topic
- Mechanism of peristalsis of the muscular coat of the ureter
- Anatomy of the rectovesical pouch
- Topography of the parametrial tissue (parametrium)
- Syntopy with the iliac vessels
- Course of the ductus deferens in the lesser pelvis
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