A novel method of lengthening the accessory nerve for direct coaptation during nerve repair and nerve transfer procedures

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The accessory nerve is frequently repaired or used for nerve transfer. The length of accessory nerve available is often insufficient or marginal (under tension) for allowing direct coaptation during nerve repair or nerve transfer (neurotization), necessitating an interpositional graft. An attractive maneuver would facilitate lengthening of the accessory nerve for direct coaptation. The aim of the present study was to identify an anatomical method for such lengthening.


In 20 adult cadavers, the C-2 or C-3 connections to the accessory nerve were identified medial to the sternocleidomastoid (SCM) muscle and the anatomy of the accessory nerve/cervical nerve fibers within the SCM was documented. The cervical nerve connections were cut. Lengths of the accessory nerve were measured. Samples of the cut C-2 and C-3 nerves were examined using immunohistochemistry.


The anatomy and adjacent neural connections within the SCM are complicated. However, after the accessory nerve was “detethered” from within the SCM and following transection, the additional length of the accessory nerve increased from a mean of 6 cm to a mean of 10.5 cm (increase of 4.5 cm) after cutting the C-2 connections, and from a mean of 6 cm to a mean length of 9 cm (increase of 3.5 cm) after cutting the C-3 connections. The additional length of accessory nerve even allowed direct repair of an infraclavicular target (i.e., the proximal musculocutaneous nerve). The cervical nerve connections were shown not to contain motor fibers.


An additional length of the accessory nerve made available in the posterior cervical triangle can facilitate direct repair or neurotization procedures, thus eliminating the need for an interpositional nerve graft, decreasing the time/distance for regeneration and potentially improving clinical outcomes.

ABBREVIATIONS SCM = sternocleidomastoid.

Article Information

Correspondence Robert J. Spinner, Department of Neurosurgery, Mayo Clinic, 200 First St. SW, Gonda 8-214, Rochester, MN 55905. email: spinner. robert@mayo.edu.

INCLUDE WHEN CITING Published online March 3, 2017; DOI: 10.3171/2016.10.JNS161106.

Disclosures The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

© AANS, except where prohibited by US copyright law.



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    Left cadaveric neck dissection noting the accessory nerve and its connections to the C-2 cervical nerve. n. = nerve. Figure is available in color online only.

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    Left cadaveric neck dissection following transection of C-2 nerve connection to the accessory nerve and removal of the clavicle to reveal the distal suprascapular and proximal musculocutaneous nerves. The sternocleidomastoid muscle (SCM) is replaced in its anatomical position. Note that the accessory nerve can easily reach the suprascapular and musculocutaneous nerves. Figure is available in color online only.

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    Schematic drawing of the concept of detethering the accessory nerve from its cervical nerve connections to allow more distance for neurotization to distal nerves. Copyright R. Shane Tubbs. Published with permission. Figure is available in color online only.

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    Immunohistochemical sections (acetylcholinesterase). Control from the enteric plexus of the colon gives positive staining (A). Neither the cross-section (B) nor the longitudinal section (C) of cervical nerve fibers joining the accessory nerve stained positively for acetylcholinesterase. Figure is available in color online only.



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