Inferior Alveolar Nerve Block

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The inferior alveolar nerve is a more proximal portion of the mental nerve. Blocking it will anesthetize the entire territory of the mental nerve, plus the mouth, teeth, and usually half of the tongue, due to diffusion into the nearby lingual nerve. It’s a great block for painful dental complaints or procedures.  


The location of the block is the pterygomandibular triangle. To locate this, retract the cheek laterally and focus just above the posterior molar. Identify the pterygomandibular fold medially and the coronoid notch laterally, which is the anterior border of the mandibular ramus. The injection site is halfway between these structures, about 1 cm above the molar. 


Before an intraoral injection, I recommend applying topical lidocaine to the site, which can be done with viscous lidocaine on a 2x2 gauze or cotton-tipped applicator or with a commercially available lidocaine product, leaving it in place for a couple of minutes. 


Using a 25-27 gauge 1 ½ inch needle, aim toward the pterygomandibular triangle. The needle should be angled slightly laterally and inserted about 1 cm above the molar. In adults, the needle is parallel to the molars, and in children, the angle is slightly inferior. You should touch bone with the needle tip to ensure the proper depth and angle. If you don’t touch bone, you are likely too lateral and may enter the parotid gland. Withdraw the needle slightly, aspirate, and inject about 2 mL of local anesthetic.


Peer reviewed by Mel Herbert, MD and Scott Kobner, MD.

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Tags Dental ENT

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