This block affects all mandibular teeth, mandibular bone, and soft tissue on the corresponding side rostral to the injection site.
Use a skull to identify the inferior alveolar nerve (short white arrow), the angular process of the mandible (yellow arrow), and the location of the intended needle placement (long white arrow). The inferior alveolar nerve is blocked before its entry into the mandibular canal.
The inferior alveolar block is performed extraorally by first palpating the indentation on the ventral border of the caudal mandible just rostral to the angular process. This indentation should be at the same rostral-to-caudal plane as the lateral canthus of the eye. So if the indentation is difficult to palpate, the lateral canthus of the eye can be used as a landmark.
Pass the needle into the skin on the lingual aspect of the caudal extent of the indentation. With the needle parallel to the lingual aspect of the mandible, advance it along the bone until it reaches one-third of the distance from the ventral to the dorsal mandibular body. The needle will now be in the vicinity of the mandibular foramen where the inferior alveolar nerve enters the mandibular canal.