Final answer:
A hematoma that quickly appeared after a PSA nerve block may have been caused by various factors, including solution being deposited into a blood vessel or the needle penetrating anatomical structures. Proper administration of the nerve block is crucial to prevent such complications.
Step-by-step explanation:
A hematoma that quickly appeared after a PSA nerve block may have been caused by solution being deposited into a blood vessel, the needle penetrating the parotid gland, or the needle penetrating the pterygoid plexus of veins. These actions can lead to bleeding and the accumulation of blood, resulting in a hematoma. It is important to properly administer the nerve block to avoid these complications.