Human Anatomy - M.M. Kurepina, A.P. Ozhigova, A.A. Nikitina 2010

Internal Organs
Urinary System
Ureters

The ureters (ureteres) are cylindrical tubes with a lumen of 4–9 mm and a length of 30–35 cm (Fig. 4.43; Atl. Figs. 202, 203). They originate from the renal pelvis and descend retroperitoneally along the posterior abdominal wall into the pelvic cavity. The Ureter is divided into abdominal and pelvic parts. The abdominal part begins at the Water/144.html">Origin of the ureter from the renal pelvis, where a bend is formed. The ureter then runs downward along The surface of the psoas major Muscle to the pelvic inlet. The pelvic part is located within the pelvic cavity, where it turns forward and downward. The ureters then obliquely pierce the posterior wall of the Urinary Bladder and open at its base through slit-like orifices.

Class="center">

Fig. 4.43. Radiograph of the Urinary Tract:

1 — renal calyces; 2 — renal pelvises; 3 — ureters

The wall of the ureter consists of three layers: an inner mucosa, a middle muscularis, and an outer adventitia (Atl. Fig. 206). The mucosa is formed by an epithelium and a lamina propria. The epithelium, as in the renal pelvis and the urinary bladder, is transitional. Collagen fibers are well-developed in the lamina propria, and lymphatic follicles are occasionally present. The mucosa forms longitudinal folds. This, along with the presence of transitional epithelium, allows the ureter to stretch. The muscular layer of the upper two-thirds of the ureter is formed by two layers of smooth muscle: an outer circular and an inner longitudinal layer. In the lower third of the ureter, a third, outer longitudinal muscle layer is added, represented by separate bundles. Peristaltic contractions of the muscular layers of the ureter (up to 5 times per minute) propel urine from the pelvis into the urinary bladder.