During an inferior alveolar injection, at what point will the needle contact bone?

• A. Two-thirds of the way
• B. One-third of the way
• C. Immediately after insertion
• D. When the needle reaches the ramus edge

Answer: (A)

The key idea is that during an inferior alveolar nerve block you advance the needle until you feel bone contact on the medial aspect of the mandibular ramus. That bone hit happens after the needle has been inserted about two-thirds of its length, which places you in the pterygomandibular space close to the mandibular foramen where the inferior alveolar nerve enters. Hitting bone at this depth confirms you’re in the correct location to deposit anesthetic near the nerve before continuing deeper or delivering the solution.

If you go too shallow, you won’t reach bone and the injection may be ineffective. If you push past bone, you risk over-penetration and potential complications. So the two-thirds depth cue helps you reliably locate the target area for successful anesthesia.