What is the recommended angle of insertion for the AC fossa?

• A. 0-5 degrees
• B. 45-60 degrees
• C. 15-30 degrees
• D. 60-90 degrees

Answer: (C)

The angle used to enter the AC fossa should follow the fossa’s natural slope, so the instrument travels along its plane rather than skimming the surface or punching straight through. A modest incline of about 15-30 degrees hits that balance: it’s shallow enough to stay within the fossa and align with its orientation, but not so shallow that control is lost or the instrument drifts off course. If the angle is too small, the tool may not seat properly or engage the fossa well; if it’s too steep, there’s a higher risk of penetrating the opposite cortex or injuring nearby structures. So, a 15-30 degree trajectory provides the best combination of alignment, stability, and safety.