[Variability of magnitude of the human jugular foramen in relation to conditions of the venous outflow after ligation of the internal jugular vein]. / Zmiennosc wielkosci otworu szyjnego czaszki czlowieka w aspekcie warunków odplywu zylnego po operacjach podwiazania zyly szyjnej wewnetrznej.

The jugular foramina of the human skull, which are the main route of the venous outflow from the skull, are characterized by laterality. It is based upon predominance of one of the sides. This event presents considerable variability in human population. These differences are probably responsible for various results of ligation of the internal jugular vein, which is performed in some clinical situations in various patients. In order to appreciate the degree of this predominance much more precisely than it is presented in the available literature, a morphological study was carried out on 78 adult human cadavers. With an aid of digital image analysing system we measured a cross-section areas of the jugular foramina of non-macerated skull. We stated that parameters of the jugular foramina didn't differ significantly in respect to age, sex and body side. Predominance of one of the jugular foramina appeared in 83% of cases, and in remaining 17% was absent (it wasn't greater than an error of measurement). If it is present, the predominance of the left and the right side are equally probable. Laterality coefficient was also calculated. It was a ratio between cross-section area of the two jugular foramina: the greater one and the smaller one. Its amount was 1.62 in men and 1.59 in women, however this difference wasn't statistically significant. The range of the laterality was rather considerable because the coefficient differed from 1.02 to 3.6. When the degree of the laterality is high, ligation of the jugular vein on the greater side could by risky. We stated that in our material here were about 2.5% of such cases.