title: Microsurgical anatomy of the posterior cerebral artery in three-dimensional images.
abstract: OBJECTIVE
  To describe the microsurgical anatomy, branches, and anatomic relationships of the posterior cerebral artery (PCA) represented in three-dimensional images.
  
  
  METHODS
  Seventy hemispheres of 35 brain specimens were studied. They were previously injected with red silicone and fixed in 10% formalin for at least 40 days. Four of the studied specimens were frozen at -10° to -15 °C for 14 days, and additional dissection was done with the Klingler's fiber dissection technique at ×6 to ×40 magnification. Each segment of the artery was measured and photographed to obtain three-dimensional stereoscopic images.
  
  
  RESULTS
  The PCA origin was in the interpeduncular cistern at the pontomesencephalic junction level in 23 specimens (65.7%). The PCA was divided into four segments: P1 extends from the PCA origin to its junction with the posterior communicating artery with an average length of 7.7 mm; P2 was divided into an anterior and posterior segment. The P2A segment begins at the posterior communicating artery and ends at the most lateral aspect of the cerebral peduncle, with an average length of 23.6 mm, and the P2P segment extends from the most lateral aspect of the cerebral peduncle to the posterior edge of the lateral surface of the midbrain, with an average length of 16.4 mm; P3 extends from the posterior edge of the lateral surface of the midbrain and ends at the origin of the parieto-occipital sulcus along the calcarine fissure, with an average length of 19.8 mm; and the P4 segment corresponds to the parts of the PCA that run along or inside both the parieto-occipital sulcus and the distal part of the calcarine fissure.
  
  
  CONCLUSIONS
  To standardize the neurosurgical practice and knowledge, surgical anatomic classifications should be used uniformly and further modified according to the neurosurgical experience gathered. The PCA classification proposed intends to correlate its anatomic segments with their required microneurosurgical approaches.
authors.affiliation: Microneurosurgery Laboratory, Beneficência Portuguesa Hospital and the Institute of Neurological Sciences, São Paulo, Brazil. rick_parraga@hotmail.com
authors.forename: Richard Gonzalo
authors.initials: RG
authors.lastname: Párraga
authors.forename: Guilherme Carvalhal
authors.initials: GC
authors.lastname: Ribas
authors.forename: Sergio Eduardo Gómez Llata
authors.initials: SE
authors.lastname: Andrade
authors.forename: Evandro
authors.initials: E
authors.lastname: de Oliveira
mesh_terms: D001921:Brain / Q000033:anatomy & histology / Q000098:blood supply / Q000601:surgery; D002102:Cadaver; D002831:Choroid Plexus / Q000033:anatomy & histology / Q000601:surgery; D004210:Dissection; D006801:Humans; D021621:Imaging, Three-Dimensional; D008866:Microsurgery; D019635:Neurosurgical Procedures; D020769:Posterior Cerebral Artery / Q000033:anatomy & histology* / Q000601:surgery*; D013699:Temporal Arteries / Q000033:anatomy & histology / Q000601:surgery