title: Clinically relevant anatomy of high anterior cervical approach.
abstract: METHODS
  An anatomic study of anterior cervical dissection of 11 embalmed cadavers and measurement of structures relative to cervical spine.
  
  
  OBJECTIVE
  To determine the anatomic relationship of the hypoglossal nerve (HN), internal and external superior laryngeal nerves (ESLNs), superior thyroid artery (STA), and superior laryngeal artery (SLA) to cervical spine and demonstrate any vulnerability.
  
  
  BACKGROUND
  The anterior approach is a common approach to the cervical spine. Much of the operative morbidity in high cervical region is related to neurovascular injury leading to dysphagia, dysphonia, impaired high-pitch phonation, and impaired cough reflex.
  
  
  METHODS
  Eleven adult cadavers (5 male/6 female) were dissected bilaterally to expose structures of the high anterior cervical region.
  
  
  RESULTS
  The HN consistently traveled toward the midline at C2-3 and was safe caudal to C3-4. In 95% of dissections, the internal superior laryngeal nerve (ISLN) was exposed within 1 cm of C3-4. The path of the ESLN was variable, but it was safe above C3-4 and below C6-7. The ESLN was deep to the STA, and it was less bulky and tauter than the ISLN in all dissections. The origin of the STA was quite variable along the carotid artery, but it was most commonly located at C4. Two anatomic variants of the SLA were observed. In 15 dissections, the SLA branched off the superior thyroid. In six dissections, the SLA branched directly from external carotid artery. There was no appreciable side-to-side variation in the neurovascular structures studied.
  
  
  CONCLUSIONS
  On the basis this study, spine surgeons can have enhanced knowledge of high anterior cervical anatomy. The neurovascular structures in this study did not demonstrate side-to-side anatomic variation; therefore, patient pathology and surgeon preference should dictate the operative side.
authors.affiliation: Department of Orthopaedic Surgery, University of Utah Health System, Salt Lake City, Utah, USA.
authors.forename: Justin M
authors.initials: JM
authors.lastname: Haller
authors.forename: Michael
authors.initials: M
authors.lastname: Iwanik
authors.forename: Francis H
authors.initials: FH
authors.lastname: Shen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001158:Arteries / Q000033:anatomy & histology*; D002102:Cadaver; D002574:Cervical Vertebrae / Q000033:anatomy & histology* / Q000601:surgery; D017586:Diskectomy / Q000379:methods; D005260:Female; D006801:Humans; D007002:Hypoglossal Nerve / Q000033:anatomy & histology*; D007823:Laryngeal Nerves / Q000033:anatomy & histology*; D007830:Larynx / Q000098:blood supply; D008297:Male; D008875:Middle Aged; D013123:Spinal Fusion / Q000379:methods; D013961:Thyroid Gland / Q000098:blood supply