BOSTON, Mass. (CBS Local) – Did you know there are tiny tunnels running from your skull to your brain? Don’t worry, no one else did either… until now.

A new study by scientists in Boston has discovered a group of secret tunnels which go from the skull’s bone marrow to the lining of the brain. It’s believed the passage ways may provide immune cells an express route to the brain in case of trauma caused by a stroke or other disorders.

“We always thought that immune cells from our arms and legs traveled via blood to damaged brain tissue,” Dr. Francesca Bosetti from the National Institute of Neurological Disorders and Stroke said in a press release.

“These findings suggest that immune cells may instead be taking a shortcut to rapidly arrive at areas of inflammation.”

Matthias Nahrendorf from Harvard Medical School and Massachusetts General Hospital focused the study on neutrophils, the immune system’s “first responders” when there’s inflammation detected in the body. Neutrophils dispatched from bone marrow in the skull or large leg bones was tracked in mice after the test subjects had an injury or suffered a stroke.

Nahrendorf and his team found that more of the immune cells where released from the skull than the leg in the event of a stroke. This prompted the researchers to find out how those “first responders” were able to reach the brain and deal with inflammation.

“We started examining the skull very carefully, looking at it from all angles, trying to figure out how neutrophils are getting to the brain,” Dr. Nahrendorf explained. “Unexpectedly, we discovered tiny channels that connected the marrow directly with the outer lining of the brain.”

The scientists added that blood is normally flowing in the opposite direction through the newly-found tunnels, but neutrophils rush in to help in case of injury. The team is now looking into what other cells may use the secret passages and what role they may play in human health.