What is the functional advantage of having air spaces in skull bones? what is the disadvantage to having these spaces lined with mucous membrane?

Ineed medicine for my ball sacks they hurt i need them rubbed on

Agroup of engineering students from purdue university reported that its licking machine, modeled after a human tongue, took an average of 364 licks to get to the center of a tootsie pop. twenty of the group's volunteers assumed the licking challenge-unassisted by machinery-and averaged 252 licks each to the center.