iD magazine - - Body & Mind -

The neu­ro­cra­nium is the por­tion of the skull that sur­rounds the brain and pro­tects it like ar­mor. Its only open­ing is lo­cated at its base, and this is where the nerves of the spinal cord meet the brain. The skull is com­posed of a se­ries of in­di­vid­ual bones con­nected by so-called su­tures and fontanelles, which are junc­tions be­tween two sec­tions of bone in the cra­nium.

Both struc­tures are nec­es­sary for our brains to grow and de­velop. In ba­bies the su­tures are still made of con­nec­tive tis­sue, and the soft gaps known as fontanelles make the in­di­vid­ual skull bones able to flex in re­la­tion to one another. This is how a baby’s head can be some­what molded to en­able it to fit through the nar­row birth canal.

In some cul­tures cer­tain head shapes cor­re­spond with an ideal of beauty. For this rea­son ba­bies’ skulls were wrapped tightly with ban­dages to mold them into such shapes. Later the su­tures os­sify and the fontanelles close— from then on the head shape is fixed. In the 19th century many doc­tors be­lieved peo­ple’s char­ac­ter could be gauged by the shape of their head. For in­stance, a crim­i­nal’s head was thought to be a cer­tain shape. Of course this as­sump­tion turned out to be to­tal non­sense.

On the inside of the skull shown be­low a fine net­work of chan­nels is vis­i­ble: The ar­ter­ies that sup­ply blood to the brain run through it.

Toby Smith* watches the truck rolling along in front of him and thinks to him­self, I can man­age that. So the mo­tor­cy­cle rider from Con­necti­cut twists the throt­tle and ac­cel­er­ates hard in a bid to over­take the large ve­hi­cle as the two driv­ers ap­proach a curve in the road. Then ev­ery­thing be­gins hap­pen­ing very quickly: the lurch­ing mo­tion of the mo­tor­cy­cle, the moment of weight­less­ness, the col­li­sion, wak­ing up in the in­ten­sive care unit, the as­ton­ished faces of the doc­tors… “After such an ex­tremely in­tense ac­ci­dent, the mo­tor­cy­clist’s whole body should have been to­tally shat­tered to pieces. But Smith was fine—he didn’t break a sin­gle bone,” re­calls physi­cian Joseph Bel­sky. The doc­tor had come to find that Smith has an ex­tremely high bone den­sity. “Do you know the film Un­break­able, in which Bruce Wil­lis plays a man who sur­vives all sorts of un­for­tu­nate sit­u­a­tions? Well, Toby Smith ac­tu­ally is un­break­able,” says Richard Lifton, chair of the depart­ment of ge­net­ics at the Yale School of Medicine. He stud­ied the genes of the en­tire Smith fam­ily. Seven of the mem­bers were found to be un­break­able. “The high bone den­sity of the fam­ily had been trig­gered by the mu­ta­tion of a sin­gle gene,” says Lifton. “None of those af­fected have ever bro­ken a bone. The only side ef­fect is a wide jaw. And the Smiths find it hard to swim due to their dense bones.”

HEAD SAND­WICH The skull is one of the most sta­ble bones in the body, thanks to a lay­ered struc­ture made of solid and spongy bone ma­te­rial. It’s sim­i­lar to how the walls of air­craft are built nowa­days. Engi­neers re­fer to this lay­er­ing as a sand­wich con­stru


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