title: Intimal musculature of the lower anterior spinal artery.
abstract: METHODS
  This was a descriptive microscopic investigation of the smooth musculature in the human lower anterior spinal artery using anatomic cadaver tissues with supporting data derived from angiographic studies of neonatal cadavers.
  
  
  OBJECTIVE
  To determine the extent and configuration of the intimal musculature in the lower anterior spinal artery and deduce the probable influence it has on the lower spinal cord blood flow, as well as its effects on the axial anastomotic potentials during aortic cross-clamping.
  
  
  BACKGROUND
  The high incidence of ischemic spinal cord injury after aortic cross-clamping has led to many studies of autoregulation of the spinal cord blood flow, but none have identified the probable vascular mechanisms.
  
  
  METHODS
  Spinal tissue blocks that included the mid-thoracic and thoracolumbar anterior spinal artery, and sections of excised anterior spinal artery were dissected from spinal cords of 16 cadavers, refixed in Bouin's solution, paraffin embedded, and microscopically studied in sections processed in Masson's trichrome stain. A radioangiographic study of barium-perfused spines of neonatal cadavers was used to substantiate histologic observations.
  
  
  RESULTS
  The smooth muscle of the tunica media of the lower anterior spinal artery is reinforced by a conspicuous longitudinally disposed layer of intimal muscle. At the junction of the arteria medullaris magna and the anterior spinal artery, this muscle forms intimal cushions that can dramatically alter the luminal diameters of the vessels involved.
  
  
  CONCLUSIONS
  The described muscular characteristics of the lower anterior spinal artery indicate it has a previously unsuspected capacity to control extrinsic and intrinsic aspects of the lower spinal cord blood flow, a factor that should be considered in clinical and experimental procedures involving spinal cord collateral circulation.
authors.affiliation: Robert E. Van Demark Institute of Anatomical Research, Department of Anatomy and Structural Biology, University of South Dakota School of Medicine, Vermillion, USA.
authors.forename: W W
authors.initials: WW
authors.lastname: Parke
authors.forename: J L
authors.initials: JL
authors.lastname: Whalen
authors.forename: P C
authors.initials: PC
authors.lastname: Bunger
authors.forename: H E
authors.initials: HE
authors.lastname: Settles
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001158:Arteries / Q000166:cytology; D002102:Cadaver; D003097:Collateral Circulation / Q000502:physiology; D006801:Humans; D007231:Infant, Newborn; D007511:Ischemia / Q000517:prevention & control; D008875:Middle Aged; D009131:Muscle, Smooth, Vascular / Q000166:cytology*; D010264:Paraplegia / Q000517:prevention & control; D011183:Postoperative Complications / Q000517:prevention & control; D011859:Radiography; D013116:Spinal Cord / Q000098:blood supply* / Q000000981:diagnostic imaging; D013119:Spinal Cord Injuries / Q000517:prevention & control; D017539:Tunica Intima / Q000166:cytology