An anatomical study was undertaken in order to investigate whether the sizes of
selected human skull foramina with significant venous compartments correlated
significantly with skull capacity. A total of 100 macerated human skulls were
examined to determine the diameter of the foramina and the skull capacity.
Measurements of the surface area of the foramina were made using a computerised
digital analysis system.
Only the size of the hypoglossal canal and jugular foramen were found to correlate
significantly with the capacity of the skull. This correlation, together with
the considerable size of the hypoglossal canal, indicated its important role in the
venous drainage of the brain.
There was considerable centralisation of venous outflow from the brain, with
60% of the area of all venous foramina of the skull occupied by jugular foramina.
Asymmetry between the right and left jugular foramina was identified, with an
average ratio of 1.6 (ranging between 1 and 3.47). In the case of right-sided
domination the correlation between the skull capacity and the size of both jugular
foramina was negative (the larger the skull cavity, the less the asymmetry),
while in the case of left-sided domination the correlation was positive. Perhaps
the left-sided domination is less advantageous for the haemodynamics of blood
outflow, as the left brachiocephalic vein is longer and is often compressed by
the sternum and aortic arch
