What are the anatomic connections to the spinal accessory nerve (SAN)?

Updated: Feb 09, 2018
  • Author: Rohan R Walvekar, MD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Connections to the SAN are as follows:

  • Greater auricular nerve (C2, C3): The greater auricular nerve may serve as a conduit between the SAN and the lesser occipital nerve and lower divisions of the trigeminal nerve. [2]

  • Cervical roots (C2, C3, C4): The cervical nerve plexus connects the SAN to the hypoglossal nerve (via the ansa hypoglossi), stellate ganglion, and mandibular branch of the facial nerve. One to three branches of the cervical plexus run to the middle and lower trapezius independent of the SAN and rarely intermingle with it. [14]

  • The SAN has a single fine branch that runs to the upper trapezius without any communication with cervical nerves. This branch does not communicate with the main trunk of the nerve that runs caudally and provides independent innervation to the upper muscle fibers of the trapezius. [14]

  • Phrenic nerve

  • Brachial plexus

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