title: The intramuscular course of the greater occipital nerve: novel findings with potential implications for operative interventions and occipital neuralgia.
abstract: BACKGROUND
  A better understanding of the etiologies of occipital neuralgia would help the clinician treat patients with this debilitating condition. Since few studies have examined the muscular course of the greater occipital nerve (GON), this study was performed.
  
  
  METHODS
  Thirty adult cadaveric sides underwent dissection of the posterior occiput with special attention to the intramuscular course of the GON. Nerves were typed based on their muscular course.
  
  
  RESULTS
  The GON traveled through the trapezius (type I; n = 5, 16.7%) or its aponeurosis (type II; n = 15, 83.3%) to become subcutaneous. Variations in the subtrapezius muscular course were found in 10 (33%) sides. In two (6.7%) sides, the GON traveled through the lower edge of the inferior capitis oblique muscle (subtype a). On five (16.7%) sides, the GON coursed through a tendinous band of the semispinalis capitis, not through its muscular fibers (subtype b). On three (10%) sides the GON bypassed the semispinalis capitis muscle to travel between its most medial fibers and the nuchal ligament (subtype c). For subtypes, eight were type II courses (through the aponeurosis of the trapezius), and two were type I courses (through the trapezius muscle). The authors identified two type IIa courses, four type IIb courses, and two type IIc courses. Type I courses included one type Ib and one type Ic courses.
  
  
  CONCLUSIONS
  Variations in the muscular course of the GON were common. Future studies correlating these findings with the anatomy in patients with occipital neuralgia may elucidate nerve courses vulnerable to nerve compression. This enhanced classification scheme describes the morphology in this region and allows more specific communications about GON variations.
authors.affiliation: Pediatric Neurosurgery, Children's Hospital, Birmingham, AL, USA ; Department of Anatomic Sciences, St. George's University, Grenada.
authors.forename: R Shane
authors.initials: RS
authors.lastname: Tubbs
authors.affiliation: Pediatric Neurosurgery, Children's Hospital, Birmingham, AL, USA.
authors.forename: Koichi
authors.initials: K
authors.lastname: Watanabe
authors.affiliation: Department of Anatomic Sciences, St. George's University, Grenada.
authors.forename: Marios
authors.initials: M
authors.lastname: Loukas
authors.affiliation: Goodman Campbell Brain and Spine, Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, Indiana, USA.
authors.forename: Aaron A
authors.initials: AA
authors.lastname: Cohen-Gadol
keywords: Anatomy; muscle; nerves; occiput; pain syndromes; skull