title: Asterion as a surgical landmark for lateral cranial base approaches.
abstract: BACKGROUND
  When approaching the posterior fossa and posterolateral cranial base, surface landmarks are helpful in locating the junction of the transverse and the sigmoid sinus.
  
  
  METHODS
  On 100 skull halves a 2mm drill bit was externally placed over the asterion and was drilled through the bone perpendicular to the skull surface. Various positions of the asterion and its distance from the root of the zygomatic process of the temporal bone, from the suprameatal crest and the mastoid tip were investigated.
  
  
  RESULTS
  The position of the asterion has been found to be located superficial to the transverse-sigmoid sinus junction in 87% of all samples, inferior to the transverse-sigmoid sinus junction in 11% and superior to the transverse-sigmoid sinus junction in 2%. The distance from the asterion to the root of the zygoma has been determined to be 54.6+/-5.5mm. The distance between asterion and Henle's spine was 45.2+/-5.2, and from asterion to Frankfurt Horizontal Plane 15+/-7.5mm.
  
  
  CONCLUSIONS
  Asterion varies regarding its cephalocaudal position. The findings of this study might have direct consequences for transmastoid and retrosigmoid approaches for microvascular trigeminal root decompression and combined petrosal approaches.
authors.affiliation: Department of Anatomy, Faculty of Medicine, Ege University, Izmir, Turkey.
authors.forename: Hulya
authors.initials: H
authors.lastname: Ucerler
authors.forename: Figen
authors.initials: F
authors.lastname: Govsa
mesh_terms: D002102:Cadaver; D002508:Cephalometry / Q000379:methods*; D003392:Cranial Sinuses / Q000033:anatomy & histology; D003393:Cranial Sutures / Q000033:anatomy & histology*; D003399:Craniotomy / Q000295:instrumentation / Q000379:methods; D006801:Humans; D008297:Male; D008416:Mastoid / Q000033:anatomy & histology*; D009777:Occipital Bone / Q000033:anatomy & histology*; D010294:Parietal Bone / Q000033:anatomy & histology*; D019291:Skull Base / Q000033:anatomy & histology* / Q000601:surgery; D013701:Temporal Bone / Q000033:anatomy & histology; D015050:Zygoma / Q000033:anatomy & histology