Penetration of the facial nerve by the posterior auricular artery: case report, comprehensive review and clinical-surgical applications.

Anatomical variations between the facial nerve and adjacent arteries are rare. However, knowledge of such anatomical variations is important to the surgeon who operates on or near the facial nerve. Herein, we report an unusual finding between the extracranial part of the facial nerve and a nearby artery. During routine dissection of the right facial nerve trunk, the posterior auricular artery was found to pierce the nerve effectively forming a nerve loop. The nerve was pierced by the artery soon after its exit from the stylomastoid foramen. This case is detailed and a review on this topic presented, specifically identifying previously reported studies describing this or similar variations, and the relationship between the posterior auricular artery and facial nerve trunk in general. Piercing of the facial nerve trunk by the posterior auricular artery appears to be rare. However, such a relationship should be known by the clinician who treats patients with pathologies of the facial nerve trunk. To our knowledge, this is the first report of this variation in an adult. Due to such rarity, this case is of archival value for those who might describe it or similar cases in the future.