foramen

noun

1. An opening, an orifice, or a short passage, especially in a bone.

   “The skull contains a number of foramina through which arteries, veins, nerves, and other structures enter and exit.”

   “There is — as I have explained — a slight want of alignment in the cervical vertebrae which has, as I perceive it, the effect of lessening the foramina through which the nerve roots emerge.”