The urinary system consists of kidneys that produce urine and the urinary tract.
The urinary tract includes the renal calyces, pelvises, ureters, urinary bladder, and urethra.
The ureter (ureter) is a paired organ that ensures the passage of urine from the renal pelvis into the urinary bladder.
The abdominal part is projected onto the right and left lateral and inguinal regions. The pelvic part is located in the cavity of the lesser pelvis.
The right ureter passes from the 1st lumbar vertebra to the 1st-2nd sacral vertebrae, and the left one passes from the 12th thoracic vertebra to the 1st-2nd sacral vertebrae.
The genitofemoral nerve passes next to the ureter, which explains the significant pain during urinary stone disease when the stone moves along the ureter.
The right ureter (ureter dexter) is located between the inferior vena cava, ascending colon, and caecum.
The descending part of the duodenum, parietal peritoneum, and root of the mesentery, as well as the mesenteric, ovarian, and testicular vessels and lymph nodes lie anteriorly to it.
The left ureter (ureter sinister) passes between the aorta and the descending colon.
Superior mesenteric arteries and veins, ovarian and testicular vessels, as well as the mesentery of the sigmoid colon and parietal peritoneum pass anteriorly to it.
The length of the ureters of an adult is approximately 35 cm.
The ureter consists of three parts:
1. Abdominal part (pars abdominalis)
2. Pelvic part (pars pelvica)
3. Intramural part (pars intramuralis), which is located in the wall of the urinary bladder.
The border between the abdominal and pelvic parts is the linea terminalis (linea terminalis).
It is formed by the promontory of the sacrum, the arcuate lines of the ilium bones, the crests of the pubis bones, and the pubic symphysis.
The ureter also may be divided into three equal parts: the superior, middle, and inferior.
The ureter has several constrictions and bends on its way from the kidney to the urinary bladder.
- Renal constriction, which is located at the beginning, at the exit from the renal pelvis
- Pelvic constriction, which is located at the intersection of the linea terminalis
- Intramural constriction, which is located in the wall of the urinary bladder
In addition, the ureter forms three segments:
- Pyeloureteral segment passes behind the renal vessels and enters the lesser pelvis along the psoas major muscle.
- Segment in the area of the crossing with the iliac vessels is a small area where the ureter circumflexes the iliac arteries and veins anteriorly.
- Vesicoureteral segment passes along the walls of the lesser pelvis and flows into the urinary bladder. In this final segment, in men, the ureters cross with the ductus deferentes, and in women, they pass posteriorly to the ovaries and laterally to the cervix of the uterus.
The wall of the ureter consists of several layers:
- The mucous membrane (tunica mucosa), which is lined with transitional epithelium.
- The muscular membrane (tunica muscularis), which has its own characteristics.
In the superior two-thirds, it consists of two layers: the external circular layer (stratum circulare) and the internal longitudinal layer (stratum longitudinale).
And in the inferior third, there are three layers. These are the external longitudinal layer (stratum externum longitudinale), middle circular layer (stratum circulare), and internal longitudinal layer (stratum internum longitudinale).
In the area of the transition of the ureter to the urinary bladder, the muscle fibers of the bladder slightly enter the wall of the ureter.
- The ureters lie retroperitoneally, so the outer sheath is adventitia (tunica adventitia). They are surrounded by the retroperiotoneal cellular tissue and sheaths of the extraperitoneal fascia.
The ureters are supplied with blood by the abdominal aorta. The superior third is supplied by the branches of the renal artery, the middle third is supplied by branches of the ovarian and testicular arteries, as well as by the internal and common iliac arteries. The inferior part of the ureter is supplied by the branches of the middle rectal artery and the arteries of the urinary bladder.
Venous drainage from the ureters occurs through the ovarian and testicular veins into the internal iliac vein.
The ureters are innervated by the sympathetic nervous system. The superior part of the ureter is regulated by the renal plexus, and the inferior part is regulated by the ureteric plexus. Pelvic splanchnic nerves also provide parasympathetic innervation.
Anatomy of the ureters
- Extraperitoneal fascia
- fascia extraperitonealis
- Abdominal part
- pars abdominalis
- Pelvic part
- pars pelvina
- Intramural part
- pars intramuralis