Final answer:
An additional finding that would indicate an infant might be in pain is increased muscle tone, evidenced by the baby having flexed arms and legs that resist extension. Muscle tone is part of the Apgar score, which is used to assess the health of newborns at birth.
Step-by-step explanation:
The subject of your question is related to assessing pain in an infant, which is a common concern in pediatric healthcare, particularly in emergency settings. In addition to the signs you've mentioned (crying, furrowed brows, and clenched fists), another indicator that an infant might be in pain would be increased muscle tone. This is observed when a baby has flexed arms and legs that resist extension, which is a typical response to discomfort or pain.
According to the Apgar score, which is a standardized scoring system used to assess the health of newborns immediately after birth, muscle tone is one of the five criteria evaluated. This scoring system indicates that a good muscle tone score is consistent with an active baby, while a lower score may be associated with poor muscle tone, possibly related to distress or other health issues.