Ureter

Ureter
Ureter (Anatomical View)
Ureter (Schematic View) 1. Human urinary system: 2. Kidney, 3. Renal pelvis, 4. Ureter, 5. Urinary bladder, 6. Urethra. (Left side with frontal section), 7. Adrenal gland Vessels: 8. Renal artery and vein, 9. Inferior vena cava, 10. Abdominal aorta, 11. Common iliac artery and vein With transparency: 12. Liver, 13. Large intestine, 14. Pelvis
Details
Latin	Ureter
Precursor	Ureteric bud
Artery	Superior vesical artery, Vaginal artery, Ureteral branches of renal artery
Identifiers
MeSH	A05.810.776
Dorlands /Elsevier	Ureter
TA
TH	{{#property:P1694}}
TE	{{#property:P1693}}
FMA	{{#property:P1402}}
Anatomical terminology [[[d:|edit on Wikidata]]]

In human anatomy, the ureters are tubes made of smooth muscle fibers that propel urine from the kidneys to the urinary bladder. In the adult, the ureters are usually 25–30 cm (10–12 in) long and ~3–4 mm in diameter. Histologically, the ureter contains transitional epithelium and an additional smooth muscle layer in the more distal one-third to assist with peristalsis.

Structure

In humans, the ureters arise from the pelvis of each kidney, and descend on top of the psoas major muscle to reach the brim of the pelvis. Here, they cross in front of the common iliac arteries. They then pass down along the sides of the pelvis, and finally curve forwards and enter the bladder from its left and right sides at the back of the bladder. This is classically depicted as running "posteroinferiorly on the lateral walls of the pelvis and then curve anteriormedially to enter the bladder". The junction between the pelvis of the kidney and the ureters is known as the pelvoureteric junction and the junction between the ureter and the bladder as the vesicoureteric junction. At the entrance to the bladder, the ureters are surrounded by valves known as ureterovesical valves, which prevent the backflow of urine.

In females, the ureters pass through the mesometrium and under the uterine arteries on the way to the urinary bladder. An effective phrase for remembering this anatomical relationship is "water (ureters) under the bridge (uterine arteries or vas deferens).

Blood supply

The ureters receive a segmental arterial supply, which varies along its course.

1. The upper part of the ureter closest to the kidney is supplied by the renal arteries
2. The middle part of the ureter is supplied by the common iliac arteries, direct branches from the abdominal aorta, and gonadal arteries (the testicular artery in men or ovarian artery in women)
3. The lower part of the ureter closest to the bladder is supplied by branches from the internal iliac arteries, as well as:

• Superior vesical artery
• Uterine artery (in women only)
• Middle rectal artery
• Vaginal arteries (in women only)
• Inferior vesical artery (in men only)

Within the periureteral adventitia these arteries extensively anastomose thus permitting surgical mobilization of the ureter without compromising the vascular supply as long as the adventitia is not stripped. Lymphatic and venous drainage mostly parallels that of the arterial supply.

Innervation

The ureters are richly innervated by nerves that travel alongside the blood vessels, building the ureteric plexus. The primary sensation to the ureters is provided by nerves that come from T12-L2 segments of the spinal cord. Thus pain may be referred to the dermatomes of T12-L2, namely the back and sides of the abdomen, the scrotum (males) or labia majora (females) and upper part of the front of the thigh.

Histology

The ureter is surrounded by urothelium, a type of transitional epithelium that is capable of responding to stretches in the ureters. The transitional epithelium may appear as a columnar epithelia when relaxed, and squamous epithelia when distended. Below the epithelium, a Lamina Propria exists. The Lamina Propria is made up of loose connective tissue with many elastic fibers interspersed with blood vessels, veins and lymphatics. The ureter is surrounded by two muscular layers, an inner longitudinal layer of muscle, and an outer circular or spiral layer of muscle.

• 

  View of the ureter under the microscope

• 

  Wall of the ureter

In other animals

Ureters are also found in all other amniote species, although different ducts fulfill the same role in amphibians and fish.

Function

The ureters are a component of the urinary system. Urine, produced by the kidneys, travels along the ureters to the bladder.

• 

  Ultrasound demonstration of ureteral jet effect

• 

  Doppler ultrasound image ureteric jet effect inside urinary bladder.

Clinical significance

Cancer of the ureters is known as ureteral cancer.

The ureters are also known for being extremely hard to work around during surgery and account for 80 percent of failed kidney transplants.

Injury

Injuries to the ureter with certain forms of trauma including penetrating abdominal injuries and injuries at high speeds followed by an abrupt stop (e.g., a high speed car accident). The ureter is injured in 0.2 per 1,000 cases of vaginal hysterectomies and 1.3 per 1,000 cases of abdominal hysterectomies, near the infundibulopelvic (suspensory) ligament or where the ureter courses posterior to the uterine vessels.

Kidney stones

A kidney stone can move from the kidney and become lodged inside the ureter, which can block the flow of urine, as well as cause a sharp cramp in the back, side, or lower abdomen. The affected kidney could then develop hydronephrosis, should a part of the kidney become swollen due to blocked flow of urine. There are three sites where a kidney stone will commonly become stuck:

• at the ureteric junction of renal pelvis;
• as the ureter passes over the iliac vessels;
• where the ureter enters into the urinary bladder (vesicoureteric junction).

Reflux

Vesicoureteral reflux refers to the reflux of fluid from the bladder to the ureters during urination. This condition can be one cause of chronic urinary tract infections, particularly in children. Vesicoureteral reflux may be treated surgically, and is believed to have a genetic basis.

External links

• Anatomy photo:40:06-0111 at the SUNY Downstate Medical Center — "Posterior Abdominal Wall: Internal Structure of a Kidney"
• Anatomy figure: 43:08-02 at Human Anatomy Online, SUNY Downstate Medical Center — "Relationship of the ureter to the uterine artery."
• Anatomy figure: 44:02-01 at Human Anatomy Online, SUNY Downstate Medical Center — "Mid-sagittal section of male pelvis."
• Anatomy image:8923 at the SUNY Downstate Medical Center
• Anatomy image:8945 at the SUNY Downstate Medical Center
• Virtual Slidebox at Univ. Iowa Slide 444
• Anatomy photo: Urinary/mammal/ureter/ureter1 - Comparative Organology at University of California, Davis — "Mammal, ureter (LM, Medium)"
• Histology at KUMC urinary-renal15 — "Ureter"
• Cross section image: pelvis/pelvis-female-17 - Plastination Laboratory at the Medical University of Vienna