dental disorders
How To Do an Inferior Alveolar Nerve Block
Relevant Anatomy
The inferior alveolar nerve is a branch of the mandibular nerve, which is the 3rd branch of the trigeminal nerve. The inferior alveolar nerve travels inferiorly and anteriorly on the medial side of the mandibular ramus. The nerve, accompanied by the inferior alveolar artery and vein, enters the mandibular foramen near the midpoint of the ramus. From this point, the nerve runs within and innervates the body of the mandible; a terminal branch, the mental nerve, reemerges through the mental foramen in the premolar region to innervate the lower lip and chin, as well as the lateral mucosa/gingiva overlying the lower incisor teeth, canine, and first premolar. After this branching, the inferior alveolar nerve continues anteriorly as the incisive nerve, to innervate the remaining teeth and bone anterior to the mental foramen up to the midline. The lingula is the bony protuberance at the anterior margin of the mandibular foramen. The coronoid notch (retromolar fossa) is the concavity of the anterior edge of the ramus, located posterior to the molars. The pterygomandibular triangle is a fatty space bordered laterally by the coronoid notch, and medially by the pterygomandibular raphe. The pterygomandibular raphe is a thin vertical band (a visible tendinous line where the buccinator and the superior pharyngeal constrictor muscles join) that borders the pterygomandibular triangle medially. The needle is inserted posterolaterally into the pterygomandibular triangle, parallel to and about 1 cm above the mandibular occlusal plane. The needle will encounter resistance as it passes through muscle and connective tissue. The anesthetic is ideally placed superiorly and posteriorly adjacent to the lingula (ie, just above the mandibular foramen). The lingual nerve (also a branch of the mandibular nerve) runs near the injection zone and is typically anesthetized incidentally to the inferior alveolar nerve block. 