Anatomical study of spinal accessory nerve using ultrasonography.

Objective: The purpose of our study was to demonstrate that ultrasonography may allow a precise assessment of the course and relationships of the spinal accessory nerve (SAN).

Material And Methods: This study, initially undertaken in 7 cadavers, was followed by high-resolution ultrasonographic study in 15 volunteers (30 nerves) by two radiologists in consensus. The location, course and relations to the adjacent anatomic structures of the SAN were analyzed.

Results: The precise course of the SAN between the lateroposterior border of the sternocleidomastoid muscle and the anterior border of the trapezius muscle could be identified by high-resolution ultrasonography. In contrast, clinical bone landmarks were not found helpful for the identification of the nerve.

Conclusion: The SAN can be clearly depicted by means of ultrasonography. Knowledge of the nerve's precise location, which may evidence individual variations, may have useful clinical applications.