Why is the ulnar artery considered unsuitable for arterial puncture?

The ulnar artery is considered unsuitable for arterial puncture primarily because it serves as a critical back-up blood supply to the hand in the event of damage or compromise to the radial artery. The radial artery is the more commonly used site for arterial puncture, particularly due to its accessibility and proximity to the surface of the skin.

When arterial puncture is performed, there is always a risk of complications, including bleeding, which can be significant if the primary vessel is compromised. The ulnar artery's role in maintaining proper blood flow to the hand makes it essential to preserve. Therefore, if the radial artery were to be damaged during a procedure, the ulnar artery can help ensure that blood supply continues to reach the hand, preventing potential ischemia.

Additionally, the ulnar artery is not as immediately accessible for puncture as the radial artery, which contributes further to its designation as unsuitable for arterial punctures in standard practice. This preference is reinforced by considerations regarding patient safety and the anatomical significance of maintaining collateral circulation.