How much body surface area (BSA) do both upper extremities account for?

The body surface area (BSA) represented by the upper extremities is an important consideration in clinical practice, especially in scenarios involving burns or medication dosages. In the "Rule of Nines," which is frequently used in emergency medicine and trauma care, the total body surface area is divided into sections that roughly approximate the percentage of the total body area.

According to this rule, each upper extremity accounts for 9% of total body surface area. Since there are two upper extremities, their combined contribution amounts to 18% of the total body surface area. Therefore, the correct answer reflects the total contribution of the upper extremities to BSA, which is 18%.

It’s important to note that one of the choices suggests that the upper extremities collectively account for 36%, which would imply each accounts for 18%, which does not align with the established reference values. Similarly, the options reflecting 24% and 9% also do not account correctly for the combined surface area of both upper extremities.

Thus, recognizing that both upper extremities contribute a total of 18% to the overall body surface area is key to applying this knowledge in clinical assessments.