title: Sensory pathways in the human embryonic spinal accessory nerve with special reference to the associated lower cranial nerve ganglia.
abstract: OBJECTIVE
  Muscles supplied by the spinal accessory nerve are particularly prone to the development of trigger points characteristic of myofascial pain. This study aimed to confirm sensory pathways in the spinal accessory nerve and to describe sensory ganglion cell distributions along the lower cranial nerve roots.
  
  
  METHODS
  Using sagittal sections of ten human embryos at 6-7 weeks and horizontal sections of three 15- to 16-week-old embryos, we analyzed ganglion cell distributions along the lower cranial nerve roots, including the spinal accessory (XI) nerve.
  
  
  RESULTS
  In all ten 6- to 7-week-old embryos, the XI nerve root contained abundant ganglion cells, which were evenly distributed along the XI nerve root at levels between the jugular foramen and the dorsal root of the second cervical nerve. However, the hypoglossal (XII) nerve roots did not contain ganglion cells and did not communicate with nearby roots in the dural space. Thus, the so-called Froriep's occipital ganglion is unlikely to be associated with the XII nerve but rather with the XI nerve roots. According to observations of three larger fetuses (15-16 weeks), most of Froriep's ganglion cells seemed to have degenerated during early fetal life.
  
  
  CONCLUSIONS
  Nociceptive sensory pathways in the adult human XI nerve may be much more limited in number than would be expected based on previous animal studies. However, it is possible that sensory ganglion cells in the embryonic XI nerve root send axons toward the developing spinal accessory nerve fibers outside of the jugular foramen.
authors.affiliation: Department of Neurology, Wonkwang University School of Medicine, Iksan, Republic of Korea, neurlogy@wonkwang.ac.kr.
authors.forename: Kwang Ho
authors.initials: KH
authors.lastname: Cho
authors.forename: Hyung Suk
authors.initials: HS
authors.lastname: Jang
authors.forename: Jin Sung
authors.initials: JS
authors.lastname: Cheong
authors.forename: Jose Francisco
authors.initials: JF
authors.lastname: Rodriguez-Vazquez
authors.forename: Gen
authors.initials: G
authors.lastname: Murakami
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Abe
mesh_terms: D000010:Abducens Nerve / Q000033:anatomy & histology* / Q000196:embryology*; D005333:Fetus; D005727:Ganglia, Spinal / Q000166:cytology*; D006801:Humans; D009619:Nociceptors / Q000502:physiology*