Inferior Alveolar Nerve Block

 IAN block as popularly called is a type of nerve block technique used to anaesthetise half of the mandible and soft tissues during Surgical procedures amenable to dental extractions, impacted tooth extraction, soft tissue minor oral surgeries. 

This is one of the most common nerve block technique used in dental practice and dental students should thoroughly learn and practice this technique for passing their dental school examinations. 

Before proceeding the technique of IAN block let's look at the anatomy of the IAN region .

• IAN nerve emerges from the lingual side of the mandible just below the Lingula.
• IAN is a terminal branch of Cranial Nerve 5 i.e Trigeminal nerve.
• It is a mixed nerve. 
• It is present in the pterygomandibular space. 
• IAN nerve block provides temporary anaesthesia to mandibular molars, premolars, canine and incisors till the midline i.e ipsilateral nerve blockage. 
• It also provides anaesthesia to buccal tissue, gingiva, labial mucosa and part of tongue. This is because while giving IAN block we also give lingual nerve block. Lingual nerve block is given while retracting the needle from pterygomandibular space. Around 0.5 -1 ml of local anaesthesia is injected as lingual nerve block while retracting the needle after giving IAN nerve block.
• IAN nerve is present in the IAN canal along with Inferior alveolar artery and vein.

Now let's look at the boundaries of the Pterygomandibular Space.

Knowledge of the Pterygomandibular space is crucial so as that we inject at the right place to get maximum efficiency of the local anaesthetic. 

Boundaries : 

1. Buccally it is bounded by the lingual surface of the mandibular ramus. 

2. Lingually it is bounded by the Medial Pterygoid Muscle.

3. Anteriorly it is bounded by the Pterygomandibular ligament. 

4. Posteriorly it is bounded by the tail of parotid gland.

Technique of IAN nerve block: 

• Retract the cheek labially using left hand and ask the patient to wide open the mouth. 
• Place thumb of left hand on the greatest depth of coronoid notch by palpating. 
• Now you can visualise the Pterygomandibular raphe. 
• Insert a 25 gauge needle slowly medial to Pterygomandibular raphe atleast 6-8 mm above occlusal plane. Direct of the needle should be form the opposite side's lower premolar towards raphe. 
• Once you hit the bone, aspirate. 
• If blood comes then it means you are near the foramen. Discard the syringe and again insert a fresh needle. 
• If aspiration is negative then slowly inject 2-3 ml of local anaesthesia and while slowly retracting the needle inject 0.5-1 ml local anaesthesia. (This is lingual nerve block)