Which point is on the upper thigh, in a depression just lateral to the sartorius muscle, at the junction of a vertical line drawn downward from the anterior superior iliac spine and a horizontal line drawn level with the lower border of the pubic symphysis?

• A. ST 31
• B. ST 33
• C. ST 30
• D. ST 32

Answer: (A)

The location being described is ST 31. It sits on the upper thigh in a hollow just lateral to the sartorius muscle, at the intersection of a vertical line dropped from the anterior superior iliac spine and a horizontal line level with the lower border of the pubic symphysis. This places the point high on the thigh near the hip, which matches the prompt’s description. The sartorius crosses the thigh, so a depression just to its lateral side marks this point. The other thigh points lie lower on the thigh or in different regions (for example, ST 32 and ST 33 are farther down the thigh, while ST 30 is on the abdomen), making ST 31 the correct fit.