What needle length is required to enter for a PSA injection?

What needle length is required to enter for a PSA injection?

• A. 5 mm
• B. 16 mm
• C. 25 mm
• D. 10 mm

Answer: (B)

The key idea here is the depth needed to reach the target nerve for a PSA block. To anesthetize the posterior superior alveolar nerve, the needle tip must reach the vicinity of the nerve as it enters the maxilla near the tuberosity. That depth is about 16 millimeters from the mucosal surface. This provides enough penetration to be near the nerve without going so deep that you risk unnecessary tissue trauma or hitting structures farther back. Shallow insertion won’t reach the nerve, while a much longer insertion isn’t necessary and increases risk. So, approximately 16 mm is the depth used to access the PSA nerve for this injection.

The key idea here is the depth needed to reach the target nerve for a PSA block. To anesthetize the posterior superior alveolar nerve, the needle tip must reach the vicinity of the nerve as it enters the maxilla near the tuberosity. That depth is about 16 millimeters from the mucosal surface. This provides enough penetration to be near the nerve without going so deep that you risk unnecessary tissue trauma or hitting structures farther back. Shallow insertion won’t reach the nerve, while a much longer insertion isn’t necessary and increases risk. So, approximately 16 mm is the depth used to access the PSA nerve for this injection.