The morphology of the hypoglossal canal and its size in relation to skull capacity in man and other mammal species.

The hypoglossal canal is a permanent element of the human skull. As well as the hypoglossal nerve, the canal also contains the venous plexus and an arterial branch leading to the dura mater. It emerged from our earlier studies that the venous plexus is a dominant component in this canal. In the present work the morphology and dimensions of the canal were studied on macerated skulls of humans and animals (rhesus monkey, European bison, fox, dog, cat, hare and rat). The hypoglossal canal was found in all the human and animal skulls examined. In both humans and animals the hypoglossal canal was frequently duplicated. The double canal was found in 43% specimens of human skulls. However, no triple division of the hypoglossal canal was found in the material under investigation. It was found that the hypoglossal canal in man, rhesus monkey and European bison had significant dimensions and in fact correlated with the size of skull capacity. This suggests that the hypoglossal canal is an essential venous emissary in man, rhesus monkey and European bison, but that in the remaining species it is of secondary importance in this respect.