Anatomic relationship between the spinal accessory nerve and internal jugular vein in the upper neck

The goal of this study was to precisely detail the relationship between the spinal accessory nerve (SAN) and the internal jugular vein (IJV) in the upper neck, specifically at the level of the posterior belly of the digastric muscle.

Case series with planned data collection.

University hospital.

This information was prospectively gathered intraoperatively in patients undergoing a neck dissection. The neck dissections were performed for the treatment or diagnosis of cancer, independent of the research goals. Eighty-six subjects underwent neck dissections, 56 unilateral and 30 bilateral. The position of the SAN was determined to be oriented lateral to the IJV, medial to the IJV, posterior to the IJV, or directly through the IJV at the level of the posterior belly of the digastric muscle.

Of 116 neck dissections, 112 (96%) were oriented lateral to the IJV at the level of the superior border of the posterior belly of the digastric muscle. In three necks (3%), the SAN was positioned medial to the IJV, and one (1%) traveled directly through the IJV.

The SAN has an intimate anatomic relationship with the IJV as it travels through the neck. The SAN is nearly always oriented lateral to the IJV, and the IJV and SAN are likely at some increased risk of injury during neck dissection in cases where the nerve travels medial to or through the IJV.