Which anatomical structure is at risk for hematoma during a PSA injection?

• A. Pterygoid plexus
• B. Inferior alveolar nerve
• C. Maxillary artery
• D. Buccal vein

Answer: (A)

The risk of a hematoma with a PSA (posterior superior alveolar) injection comes from the venous structures in the infratemporal region, specifically the pterygoid venous plexus. As the needle is guided near the maxillary tuberosity to reach the PSA area, it can nick branches that drain into this plexus. If the plexus is breached, blood can pool in the surrounding spaces, producing a hematoma in the cheek or infratemporal region. The pterygoid plexus is a network of veins that surrounds the pterygoid muscles and connects with the maxillary vein, so it is the structure most directly involved in this hematoma risk.

The other structures are less relevant to hematoma formation in this context. The inferior alveolar nerve is a nerve, so injury would more likely cause sensory changes rather than a hematoma. The maxillary artery is a deep, high-pressure artery; damaging it could cause significant, brisk arterial bleeding but is less commonly the source of a typical PSA-related hematoma described in preclinical and clinical guidance. The buccal vein is a smaller superficial vein and not the primary vessel involved in the usual PSA hematoma scenario.