Final answer:
The usual site for capillary puncture in adults is the ring finger, not the median cubital vein, which is commonly used for venous blood draws.
Step-by-step explanation:
The usual site for capillary puncture in adults is the ring finger. Capillary punctures are commonly used for obtaining small blood samples and the distal phalanx of the ring finger provides a suitable location. When performing a capillary puncture, an area with a rich capillary bed is selected, and the ring finger offers a site that is less painful and has a good blood flow for sampling purposes. It is important to note that while the median cubital vein is often used for venous blood draws due to its accessibility and size, it is not the typical site for a capillary puncture.