What is the name of the proximal, funnel shaped portion of the ureter called?

The proximal, funnel-shaped portion of the ureter is called the renal pelvis. This structure acts as a collecting basin for urine produced in the kidneys before it flows into the ureter. The renal pelvis is formed by the convergence of the major calyces, which are themselves responsible for collecting urine from the renal pyramids. This anatomical feature is crucial because it enables the efficient transportation of urine from the kidney to the ureter, which then leads to the bladder.

Understanding this structure is important in the context of urinary anatomy and function, as it plays a key role in the renal system's ability to channel urine effectively. The other options do not represent this part of the urinary system at all; for example, calyx refers to a cup-like structure around the renal pyramids, the ureteral sphincter is a muscle controlling urine flow, and the urethra is the tube through which urine exits the body.