What is the expanded proximal end of the ureter known as?

The expanded proximal end of the ureter is known as the renal pelvis. This structure serves as a funnel that collects urine from the renal calyces (the chambers within the kidney) and directs it into the ureter for transport to the bladder. The renal pelvis plays a crucial role in the urinary system, as it is the point where urine exits the kidney and begins its journey through the ureter.

In contrast, the other options refer to different anatomical structures. The urethra is the duct that conveys urine from the bladder to the outside of the body, the kidney capsule is a protective layer surrounding the kidneys, and the bladder neck is the area of the bladder that connects to the urethra. Each of these plays its own unique role in the urinary system, but none of them represent the expanded section of the ureter as accurately as the renal pelvis does.