Which combination of landmarks is used to locate the PSA nerve block site?

• A. Mucobuccal fold, maxillary tuberosity, zygomatic process of maxilla
• B. Infraorbital foramen, zygomatic bone
• C. Hard palate midline
• D. Alveolar crest

Answer: (A)

Locating the PSA nerve block site relies on three reliable surface landmarks that guide you to the posterior superior alveolar nerve as it enters the maxilla. Start at the mucobuccal fold above the maxillary second molar, which tells you where to enter the tissues. The maxillary tuberosity provides a posterior reference point and helps you judge how far back the needle should travel toward the PSA foramina. The zygomatic process of the maxilla serves as a superior-lateral guide, helping align the needle toward the posterior aspect of the maxilla where the PSA nerve fibers are located. These landmarks together direct the needle path upward, inward, and posteriorly to reach the PSA nerve before it branches. The other landmark combinations point to different nerve blocks or techniques (infraorbital-related landmarks, hard palate landmarks for nasopalatine, or non-specific crestal references), which is why this trio is the correct set for the PSA approach.