[Morphologic study of the inferior cavo-atrial transition in man. Morphofunctional considerations].
OBJECTIVE
Analysis the fibrous elements of the transition between the inferior vena cava and right atrium.


METHODS
Twenty adult (20-40 ys) were used. Properly preserved samples were analysed macro and microscopically. Fragments were excised from the inferior cavo-atrial transition and analysed under stereomicroscopic.


RESULTS
The inferior vena cava valve was disposed at the wall of the vein. Insertions of striated muscular cardiac fibers bundles are seen at the anterior wall of inferior vena cava. These muscular bundles are directed towards the intima of the vein. There were at the venous posterior wall insertions of the cardiac muscular bundles, originated from the crista terminalis and from the interatrial septum, these bundles show an orientation predominantly oblique, with tendency to become circular. At the transition level, the bundles of smooth muscular fibers of the inferior vena cava, presented an oblique disposition, becoming predominantly circular.


CONCLUSIONS
As the disposition of muscular cardiac fibers presents a predominantly circular direction and, the bundles of smooth muscular fibers of the inferior vena cava present the same direction, we could postulate that, when the atrial systole occurs, these muscular bundles would obliterate the cavo-atrial transition, preventing, this way, the venous reflux.
Jacomo
A L
AL
Instituto de Ciências Biomédicas da Universidade de São Paulo.
Rodrigues Júnior
A J
AJ
Rodrigues
C J
CJ
Biazotto
W
W
D000328:Adult; D004547:Elastic Tissue / Q000033:anatomy & histology; D005260:Female; D006325:Heart Atria / Q000033:anatomy & histology*; D006801:Humans; D008297:Male; D014682:Vena Cava, Inferior / Q000033:anatomy & histology*
Estudo morfológico da transição cavo-atrial inferior no homem. Considerações morfo-funcionais.