Histologic confirmation of neuronal cell bodies along the spinal accessory nerve

Most sources conclude that the spinal accessory nerve (SAN) is a purely motor nerve. There are some reports that suggest a sensory component, although the exact nature of such sensory fibers has yet to be elucidated. With such discrepancies in the literature and with well-established pain syndromes of unknown etiology following SAN injury, the authors performed the present study to better clarify this anatomy.

The entire accessory nerve was harvested from 10 adult cadavers. Samples were then submitted for immunohistochemical analyses.

Occasional microganglia cells were identified along the SAN in all specimens. These ganglia were most numerous along the intracranial segment of the SAN, but none was found along the cranial rootlets of the accessory nerve.

Neuronal cell bodies were identified along the course of the SAN in human cadavers. Although the function is not certain, such cells have been found in other animals to be nocioceptive in nature. Pending further study, these cells may be found to be involved in enigmatic pain syndromes thought to arise in the sternocleidomastoid and trapezius muscles.