Certified Surgical First Assistant (CSFA) Practice Test

Into which structures of the kidney does urine drain before reaching the ureter?

1. Minor calyces

2. Major calyces

3. Renal pyramids

4. Renal cortex

The correct answer is: Major calyces

Urine drainage in the kidney follows a specific path before it enters the ureter. It first collects in the minor calyces, which are small cup-like structures that surround the renal papillae of the renal pyramids. These minor calyces then unite to form the major calyces. The major calyces act as larger collection points, gathering urine from multiple minor calyces, and then they converge into the renal pelvis, which ultimately drains into the ureter. While the renal cortex and renal pyramids do play a role in the formation and transportation of urine within the kidney, they do not serve as structures through which urine drains before entering the ureter. The renal cortex is the outer layer housing the nephron units, where filtration occurs, and the renal pyramids contain the collecting ducts that carry urine toward the minor calyces. However, it is the major calyces that are directly involved in the transition of urine to the ureter after it has drained from the minor calyces. Thus, the major calyces are indeed the correct answer to this question about the pathway of urine drainage in the kidneys.