Human Anatomy - Kotsan I. Y. 2009

Urogenital Apparatus
Urinary Organs
Ureter

The ureter is a paired organ that Functions to transport urine from the renal pelvis to the Urinary Bladder. It is a tube-like Structure, 30–35 cm long and 3–8 mm wide (Fig. 169). In women, the Ureters are 2–3 cm shorter than in men. The ureter is retroperitoneal in position. Emerging from the Kidneys, the right and left ureters descend along the posterior abdominal wall into the pelvic cavity. Within the pelvis, each ureter reaches the Base of the urinary bladder, pierces its wall obliquely, and opens into the bladder cavity via a slit-like orifice. Based on its topography, the ureter is divided into abdominal, pelvic, and intramural parts.

The abdominal part (pars abdominalis) of the ureter lies on the anterior surface of the psoas major Muscle. The Water/144.html">Origin of the right ureter is located posterior to the descending part of the duodenum, while the left ureter lies posterior to the duodenojejunal flexure. Anterior to the ureter are the testicular (in men) or ovarian (in women) artery and vein, as well as the parietal Peritoneum.

The pelvic part (pars pelvica) of the right ureter crosses anterior to the right internal iliac artery and vein, whereas the left ureter crosses anterior to the common iliac artery and vein. In the pelvic cavity, each ureter is situated anterior to the internal iliac artery and medial to the obturator artery and vein. In women, the pelvic part of the ureter passes posterior to the Ovary, then loops laterally around the cervix of the Uterus, coming to lie between the anterior vaginal wall and the urinary bladder. In men, the pelvic part is located lateral to the Ductus deferens, crosses it, and enters the urinary bladder slightly inferior to the upper margin of the Seminal Vesicle.

The intramural part (pars intramuralis) of the ureter is embedded within the wall of the urinary bladder and is 1.5–2 cm in length.

The wall of the ureter consists of three layers: an inner mucous membrane (mucosa), a middle muscular layer (muscularis), and an outer adventitial layer (adventitia).

The mucous membrane (tunica mucosa) of the ureter is lined with epithelium, contains numerous mucous glands, and forms multiple longitudinal folds.

The muscular coat (tunica muscularis) along almost the entire length of the ureter consists of two layers of smooth muscle: an outer longitudinal layer and an inner circular layer, except for its lower portion, which features three layers: inner and outer longitudinal layers and a middle circular layer. Contractions of the muscular layers of the ureter (up to 5 times per minute) propel urine from the renal pelvis into the urinary bladder.

The adventitial coat (tunica adventitia) of the ureter is formed of Connective Tissue and is richly supplied with Blood Vessels and nerves.

The lumen of the ureter is not uniform in diameter, exhibiting three narrowings: 1) at the junction of the renal pelvis and the ureter; 2) at the transition from the abdominal part of the ureter to the pelvic part; 3) at the opening of the ureter into the urinary bladder. In a living person, In addition to the anatomical narrowings mentioned above, a series of physiological constrictions associated with ureteral peristalsis can be observed.

Along its course, the ureter exhibits two curvatures in the frontal plane: medially in the lumbar region, and laterally in the pelvic region. Occasionally, the ureter appears straight in the lumbar region. The curvature of the pelvic part is consistent.

The Blood supply to the ureter is derived from multiple sources. The upper part of the ureter is supplied by Branches of the renal, testicular, or ovarian Arteries. The middle part receives blood from ureteral branches originating from the Abdominal Aorta, while the lower part is supplied by branches arising from the middle rectal and inferior vesical arteries. Venous blood from the ureter drains into the lumbar, testicular (ovarian), and internal iliac Veins.

The Lymphatic vessels of the ureter drain into the lumbar and internal iliac Lymph Nodes.

The NERVES OF THE ureter originate from the renal, ureteral, and hypogastric plexuses. Parasympathetic Innervation of the upper part of the ureter is derived from the Vagus nerve (via the renal plexus), and that of the lower part from the pelvic splanchnic nerves.