A natural hole, passage, or opening in a bone or other body structure: "Although a foramen is usually through a bone, it can be an opening through other types of body tissue which permits the passage of nerves or blood vessels."

"There are many foramens in the cranium, or skull, that make it possible for the nerves and blood vessels pass through."

"Cranial nerves supply most of the sensory structures and muscles of the head and neck and the blood vessels that carry blood to and from the brain go through the foramens."