What anatomical structure is at risk when administering an IAN block too posteriorly and laterally?

When administering an inferior alveolar nerve (IAN) block too posteriorly and laterally, the anatomical structure at significant risk is the facial nerve. The facial nerve is located within the parotid gland, which is positioned laterally to the mandibular ramus. If the needle is directed too posteriorly during the IAN block, it may inadvertently penetrate the parotid gland, where the facial nerve runs, leading to potential facial nerve injury. This could manifest as motor deficits in the muscles of facial expression on the affected side, which is a serious complication.

In contrast, while the other structures mentioned may also be important considerations during this procedure, they are less likely to be at immediate risk from improper IAN block technique as compared to the facial nerve. The lingual nerve is situated more medially and is typically not at risk from a posterior and lateral approach. The inferior alveolar artery is generally located close to the inferior alveolar nerve but is not as closely related to the specific risk of a posteriorly placed needle. The pterygoid plexus is located further posterior and superior, and while potential puncture could lead to hematoma, it is not the primary concern when the needle is improperly positioned.

Therefore, understanding the anatomical