Objective-To assess the arrangement of myocardial bridges.Design-A necropsy study of 90 consecutive hearts (56 male, 34 female).Results-Myocardial bridges, either single or multiple, were seen in 50 (55-6%) of the 90 hearts. The left anterior descending artery was the most commonly affected artery. Thirty five of the 50 hearts which contained in total 41 muscle bridges were dissected further with a magnifying glass. Two different types of muscle bridges could be identified. Thirty one of these 41 myocardial bridges were superficial, crossing the artery transversely towards the apex of the heart at an acute angle or perpendicularly. The individual ages ranged from a stillbirth to 84 years and in none was there a history of preceding established cardiac disease and death was not referrable to cardiac causes. Myocardial bridges were identified in 50 hearts. Thirty five of these hearts were examined further by hand lens dissection. Thirteen of the remaining 15 hearts, in which the left anterior descending coronary artery was directly related to a muscle bundle, were assessed histologically. After fixation, five were embedded in paraffin and 10 gum sections were cut, and four were embedded in 8% celloidin and 100 gum sections were cut.The sections were then stained by azan and resorcin fuschin and the azan and Weigert method respectively to demonstrate connective and elastic tissue. Segments of four hearts which included muscle bridges were cut at 60 ,um in a cryostat and stained by Sudan III to assess the adipose tissue interposed between the artery and the muscle bridge. The remaining two hearts were set aside for ultrastructural investigation. STATISTICAL TESTSWe used Student's t test for paired and unpaired samples with Fisher tests for variance and multiple comparison analysis. P values < 0 05 were considered significant. ResultsThirty two of the 50 hearts that contained muscle bridges came from male subjects. In 35 hearts the bridges were single, affecting solely the left anterior descending coronary artery; 10 hearts contained two muscle bridges and five hearts contained three muscle bridges. These multiple muscle bridges affected either the same vessel or different coronary arteries or their branches. Significantly longer muscle bridges were seen in the 21-50 age group than in the hearts removed from subjects 0-20 years (table 1). There was no statistical difference between the length of myocardial bridges in male and female subjects (table 2). Shorter muscle bridges were more common (table 3 and fig 1).

RESUMO -São apresentadas as características anatômicas da artéria coróidea anterior (AChA), encontradas nas dissecações de 100 hemisférios cerebrais de cadáveres humanos, realizadas sob microscópio cirúrgico.Foi encontrada uma AChA por hemisfério cerebral, 98% originando-se da artéria carótida interna (ACI) 2,4mm distai à origem da artéria comunicante posterior (ACoP) e 4,7mm proximal à bifurcação da ACI. Em 29% dos hemisférios havia ramos perfurantes emergindo da porção comunicante da ACI. A média do calibre da AChA foi 0,9mm na sua porção cisternal e 0,7mm na porção plexal.Os ramos mais freqüentes da porção cisterna da AChA foram para o trato óptico, pedúnculo cerebral, uncus e corpo geniculado lateral.Foram observadas anastomoses de ramos da AChA com ramos da artéria cerebral posterior, ACoP, artéria cerebral média e ACI. Os resultados são comparados àqueles da literatura. Microsurgical anatomy of the anterior choroidal artery.SUMMARY -Microdissection of 100 hemispheres from human cadavers were performed in order to study the anatomic characteristics of the anterior cheroidal artery (AChA). One AChA per hemisphere was found. In 98% of hemispheres the AChA arose from the internal carotid artery (ACI) 2.4mm distal to the origin of the posterior communicating artery (ACoP) and 4.7mm proximal to the carotid bifurcation.One or more perforating branches arose from communicating segment of ACI in 29% of hemispheres.The average calibre of the cisternal portion was 0.9mm and the plexal portion 0.7mm.The most frequent branches of the cisternal portion pass to the optic tract, cerebral peduncle, uncus and lateral geniculate body. Anastomosis were found between branches of the AChA and posterior cerebral artery, ACoP, middle cerebral artery and ACI. The results are discussed.Desde 1786 os vasos coróideos são conhecidos na literatura. Em 1925 foi descrito que a oclusão da artéria coróidea anterior (AChA) causaria no lado contralateral hemiplegia, hemianestesia e hemianopsia ^-23 .Cooper 5 preconizou a ligadura da AChA, para melhora do tremor e da rigidez na doença de Parkinson. Mais tarde, este procedimento foi abandonado em virtude dos seus resultados incertos 22 A AChA origina-se da parede posterior da artéria carótida interna (ACI), na cisterna carotídea, abaixo e lateral ao trato óptico (TO). Inicialmente tem trajeto póstero-medial, cruza o TO no sentido lateral-medial, acompanhando a borda mediai deste e, na cisterna crural, alcança a margem lateral do pedúnculo cerebral. Na parte anterior do corpo geniculado lateral (CGL) descruza o TO chegando à fissura corói-dea (FC). A seguir penetra no plexo coróide (PC) do corno temporal do ventrículo lateral (VL), percorrendo sua borda mediai, em íntima relação com a artéria coróidea posterior lateral (ACPL) com cujos ramos se anastomosa. A AChA é dividida em porção cisternal, que compreende desde sua origem até a FC, e porção plexal, desde a FC até a sua terminação 8,13.

RESUMO KEYWORDS Intracranial aneurysm, cerebral angiography, basilar artery, vertebral artery.