title: Microsurgical Anatomy of the Hypoglossal and C1 Nerves: Description of a Previously Undescribed Branch to the Atlanto-Occipital Joint.
abstract: OBJECTIVE
  Distal branches of the C1 nerve that travel with the hypoglossal nerve have been well investigated but relationships of C1 and the hypoglossal nerve near the skull base have not been described in detail. Therefore, the aim of this study was to investigate these small branches of the hypoglossal and first cervical nerves by anatomic dissection.
  
  
  METHODS
  Twelve sides from 6 cadaveric specimens were used in this study. To elucidate the relationship among the hypoglossal, vagus, and first and cervical nerve, the mandible was removed and these nerves were dissected under the surgical microscope.
  
  
  RESULTS
  A small branch was found to always arise from the dorsal aspect of the hypoglossal nerve at the level of the transverse process of the atlas and joined small branches from the first and second cervical nerves. The hypoglossal and C1 nerves formed a nerve plexus, which gave rise to branches to the rectus capitis anterior and rectus capitis lateralis muscles and the atlanto-occipital joint.
  
  
  CONCLUSIONS
  Improved knowledge of such articular branches might aid in the diagnosis and treatment of patients with pain derived from the atlanto-occipital joint. We believe this to be the first description of a branch of the hypoglossal nerve being involved in the innervation of this joint.
authors.affiliation: Seattle Science Foundation, Seattle, Washington, USA; Department of Anatomy, Kurume University School of Medicine, Kurume, Fukuoka, Japan; Dental and Oral Medical Center, Kurume University School of Medicine, Kurume, Fukuoka, Japan. Electronic address: joei@seattlesciencefoundation.org.
authors.forename: Joe
authors.initials: J
authors.lastname: Iwanaga
authors.affiliation: Seattle Science Foundation, Seattle, Washington, USA; Swedish Neuroscience Institute, Swedish Medical Center, Seattle, Washington, USA.
authors.forename: Christian
authors.initials: C
authors.lastname: Fisahn
authors.affiliation: Swedish Neuroscience Institute, Swedish Medical Center, Seattle, Washington, USA.
authors.forename: Fernando
authors.initials: F
authors.lastname: Alonso
authors.affiliation: Swedish Neuroscience Institute, Swedish Medical Center, Seattle, Washington, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: DiLorenzo
authors.affiliation: Swedish Neuroscience Institute, Swedish Medical Center, Seattle, Washington, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Grunert
authors.affiliation: Center for Pain Medicine, Bryn Mawr, Pennsylvania, USA.
authors.forename: Matthew T
authors.initials: MT
authors.lastname: Kline
authors.affiliation: Department of Anatomy, Kurume University School of Medicine, Kurume, Fukuoka, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Watanabe
authors.affiliation: Seattle Science Foundation, Seattle, Washington, USA; Swedish Neuroscience Institute, Swedish Medical Center, Seattle, Washington, USA.
authors.forename: Rod J
authors.initials: RJ
authors.lastname: Oskouian
authors.affiliation: Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Spinner
authors.affiliation: Seattle Science Foundation, Seattle, Washington, USA; Department of Anatomical Sciences, St. George's University, West Indies, Grenada.
authors.forename: R Shane
authors.initials: RS
authors.lastname: Tubbs
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D059925:Anatomic Landmarks / Q000033:anatomy & histology; D001269:Atlanto-Occipital Joint / Q000033:anatomy & histology* / Q000294:innervation*; D002102:Cadaver; D066193:Cervical Cord / Q000033:anatomy & histology*; D004210:Dissection / Q000379:methods; D005260:Female; D006801:Humans; D007002:Hypoglossal Nerve / Q000033:anatomy & histology* / Q000601:surgery; D008297:Male; D008866:Microsurgery / Q000379:methods*; D013127:Spinal Nerves / Q000033:anatomy & histology* / Q000601:surgery
keywords: Anatomy; Cadaver; Cranial nerves; Hypoglossal nerve; Microscopy