Anatomical Science International

, 82:1

Is the cranial accessory nerve really a portion of the accessory nerve? Anatomy of the cranial nerves in the jugular foramen

Authors

  • Shaun Ryan
    • Department of Anatomy with RadiologyFaculty of Medical and Health Sciences, University of Auckland
  • Phil Blyth
    • Department of Anatomy with RadiologyFaculty of Medical and Health Sciences, University of Auckland
  • Nick Duggan
    • Department of Anatomy with RadiologyFaculty of Medical and Health Sciences, University of Auckland
  • Martin Wild
    • Department of Anatomy with RadiologyFaculty of Medical and Health Sciences, University of Auckland
    • Department of Anatomy with RadiologyFaculty of Medical and Health Sciences, University of Auckland
Original article

DOI: 10.1111/j.1447-073X.2006.00154.x

Cite this article as:
Ryan, S., Blyth, P., Duggan, N. et al. Anato Sci Int (2007) 82: 1. doi:10.1111/j.1447-073X.2006.00154.x

Abstract

The accessory nerve is traditionally described as having both spinal and cranial roots, with the spinal root originating from the upper cervical segments of the spinal cord and the cranial root originating from the dorsolateral surface of the medulla oblongata. The spinal rootlets and cranial rootlets converge either before entering the jugular foramen or within it. In a recent report, this conventional view has been challenged by finding no cranial contribution to the accessory nerve. The present study was undertaken to re-examine the accessory and vagus nerves within the cranium and jugular foramen, with particular emphasis on the components of the accessory nerve. These nerves were traced from their rootlets attaching to the spinal cord and the medulla and then through the jugular foramen. The jugular foramen was exposed by removing the dural covering and surrounding bone. A surgical dissecting microscope was used to trace the roots of the glossopharyngeal nerve (CN IX), vagus nerve (CN X) and accessory nerve (CN XI) before they entered the jugular foramen and during their travel through it. The present study demonstrates that the accessory nerve exists in two forms within the cranial cavity. In the majority of cases (11 of 12), CN XI originated from the spinal cord with no distinct contribution from the medulla. However, in one of 12 cases, a small but distinct connection was seen between the vagus and the spinal accessory nerves within the jugular foramen.

Key words

accessory nervehumanjugular foramenvagus nerve

Copyright information

© Japanese Association of Anatomists 2006