Final answer:
The trigeminal nerve (CN V) is responsible for transmitting the pain signals as you clean the patient's abrasion.
Step-by-step explanation:
The nerve that is transmitting the pain signals as you clean the patient's abrasion is the trigeminal nerve (CN V). This nerve is responsible for providing sensory information from the face and head, including pain sensation. When the patient winces in pain, it is the trigeminal nerve that is transmitting the pain signals from the abrasion to the brain.