title: "Triple cross" of the hypoglossal nerve and its microsurgical impact to entrapment disorders.
abstract: OBJECTIVE
  Cadaveric dissections were performed to review the intracranial and extracranial course of the hypoglossal nerve. The neurological significance of a newly defined "triple cross" of the hypoglossal nerve is discussed.
  
  
  METHODS
  10 cadaveric heads (left and right; 20 sides) were dissected using microsurgical techniques.
  
  
  RESULTS
  In the cisternal segment of hypoglossal nerve, the diameter of the rostral trunk amounted to 155-680 microm (mean 435 microm), and the caudal trunk to 210-820 microm (mean 482 microm). The roots formed three trunks in 20% of the hypoglossal nerves and two trunks in the rest. As a first cross, the anterior medullary segment of the vertebral artery crossed the hypoglossal nerve roots in 14 of 20 sides (70%). As a rare variation, the vertebral artery extended medial to the nerve (25%) or between its roots (5%). The second cross was found between the descendens hypoglossus and the occipital artery (75%), sternocleidomastoid artery and vein complex (15%) and external carotid artery (10%). The third cross was shown in the submandibular triangle between the lingual hypoglossus and its drainage vein; vena committans nervus hypoglossus.
  
  
  CONCLUSIONS
  Throughout its way, the hypoglossal nerve passes over vascular structures in three crossing points which may serve as a probable cause of hypoglossal nerve entrapment disorders.
authors.affiliation: Department of Neurosurgery, University of Kirikkale, Kirikkale, Turkey. bademci70@yahoo.com
authors.forename: G
authors.initials: G
authors.lastname: Bademci
authors.forename: F
authors.initials: F
authors.lastname: Batay
authors.forename: M G
authors.initials: MG
authors.lastname: Yaşargil
mesh_terms: D000328:Adult; D001808:Blood Vessels / Q000033:anatomy & histology*; D002342:Carotid Artery, External / Q000033:anatomy & histology; D019299:Decompression, Surgical / Q000379:methods / Q000592:standards; D004210:Dissection / Q000379:methods*; D006801:Humans; D007002:Hypoglossal Nerve / Q000033:anatomy & histology* / Q000601:surgery; D020437:Hypoglossal Nerve Diseases / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery; D007431:Intraoperative Complications / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control; D007601:Jugular Veins / Q000033:anatomy & histology; D008866:Microsurgery / Q000379:methods / Q000592:standards; D009408:Nerve Compression Syndromes / Q000503:physiopathology* / Q000601:surgery; D019635:Neurosurgical Procedures / Q000379:methods / Q000592:standards; D014059:Tongue / Q000294:innervation; D014711:Vertebral Artery / Q000033:anatomy & histology