Final answer:
The urinary bladder receives its blood supply mainly from the superior and inferior vesical arteries, which are branches of the internal iliac artery, supplying blood to pelvic organs and regions.
Step-by-step explanation:
The two primary sources of blood supply to the urinary bladder are superior and inferior vesical arteries, which are branches of the internal iliac artery. The internal iliac artery branches off from the common iliac arteries, which are themselves divisions of the aorta at approximately the level of vertebra L4. Each internal iliac artery provides blood to the urinary bladder, walls of the pelvis, external genitalia, and the medial portion of the femoral region. Additionally, in females, the internal iliac artery branches also supply blood to the uterus and vagina.