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<div><font size=3D"2"> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org= /TR/xhtml1/DTD/xhtml1-strict.dtd"><html xmlns=3D"http://www.w3.org/1999/xht= ml"><head> <meta content=3D"text/html; charset=3DUTF-8" http-equiv=3D"Content-Type= "/> </head><body style=3D""> =20 =20 <div>    An intereting study. However, at least in humans, whiplash = injuries (or acceleration-deceleration injuries) are caused by overstretchi= ng of neck ligaments and muscles, not by reduced blood supply to the brain.= . And our carotid and vertebral arteries are normally connected, too, = through the circle of Willis, even though we cannot rotate our necks a= s much as the owls... <br/>   Dusan Soudek </div>=20 <div> <br/>---------- Original Message ---------- <br/>From: "Laviolette, Lance (EXP)" <lance.laviolette@lmco.= com> <br/>To: "naturens@chebucto.ns.ca" <naturens@chebucto.ns.ca&= #62; <br/>Date: February 25, 2013 at 10:46 AM <br/>Subject: [NatureNS] Owl's Extreme Head Rotation Explained </div>=20 <div style=3D"position: relative;">=20 <div> Hi Everyone, </div>=20 <div>   </div>=20 <div> I came across an article noting that scientists at Johns Hopkins Medici= ne had uncovered the reasons why an owl can almost fully rotate its heads. = I=E2=80=99ve pasted a summary of the article below with a link to the full = article afterward for those of you who are interested. All the best, </div>=20 <div>   </div>=20 <div> Lance </div>=20 <div> <span style=3D"font-size: small;"> </span> </div>=20 <div> <span style=3D"font-size: small;">=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D</span> </div>=20 <div> <span style=3D"font-size: small;">After much research, scientists at Jo= hn Hopkins University have determined how owls are able to rotate their hea= ds up to 270 degrees without damaging their blood vessels.</span> </div>=20 <div> <span style=3D"font-size: small;"> </span> </div>=20 <div> <span style=3D"font-size: small;">Humans get whiplash from rapid, twist= ing head movements because that damages the arteries supplying blood to the= brain. Researchers have discovered four special adaptations that keep owls= from having a stroke every time they turn to watch potential prey.</span> </div>=20 <div> <span style=3D"font-size: small;"> </span> </div>=20 <div> <span style=3D"font-size: small;"><strong>Arterial Reservoirs</strong><= /span> </div>=20 <div> <span style=3D"font-size: small;">The scientists discovered that blood = vessels at the base of owl=E2=80=99s heads get larger and fill with blood a= s the head turns. These arteries are pooling blood to minimize any interrup= tions in blood flow to the owl=E2=80=99s brain and eyes. Human arteries, in= comparison, remain small and do not increase in size as they branch out.</= span> </div>=20 <div> <span style=3D"font-size: small;"> </span> </div>=20 <div> <span style=3D"font-size: small;"><strong>Larger Holes in Vertebrae</st= rong></span> </div>=20 <div> <span style=3D"font-size: small;">The holes in an owl=E2=80=99s vertebr= ae are ten times the size of the arteries which run through them. The large= r holes create cushioning air pockets which allows for more flexibility and= movement of the arteries, which prevents them from being damaged. This dif= fers from human=E2=80=99s vertebral holes, which hug the arteries snugly.</= span> </div>=20 <div> <span style=3D"font-size: small;"> </span> </div>=20 <div> <span style=3D"font-size: small;"><strong>Higher Artery Entrance</stron= g></span> </div>=20 <div> <span style=3D"font-size: small;">Owl=E2=80=99s vertebral arteries were= also found to enter the vertebrae higher up than in most birds, entering t= he 12th vertebrae instead of the 14th. This gives the arteries more room an= d slack , which allows for greater movement.</span> </div>=20 <div> <span style=3D"font-size: small;"> </span> </div>=20 <div> <span style=3D"font-size: small;"><strong>Carotid and Vertebral Artery = Connections</strong></span> </div>=20 <div> <span style=3D"font-size: small;">The vertebral and carotid arteries in= owls contain small connections that allow them to share blood between each= other. This allows blood to be exchanged in the event that one or the othe= r is blocked, ensuring continuous blood flow to the owl=E2=80=99s brain. Th= ere are only rare examples of this found in human anatomy.</span> </div>=20 <div> <span style=3D"font-size: small;"> </span> </div>=20 <div> <span style=3D"font-size: small;">According to the scientists, these fo= ur adaptations are what allow owls to turn their heads in such an extreme f= ashion without any adverse effects.</span> </div>=20 <div> <span style=3D"font-size: small;"> </span> </div>=20 <div> <span style=3D"font-size: small;">The team from John Hopkins had their = findings acknowledged in the journal Science February 1st as the winners of= the National Science Foundation=E2=80=99s 2012 International Science &= Engineering Visualization Challenge.</span> </div>=20 <div> <span style=3D"font-size: small;"> </span> </div>=20 <div> <span style=3D"font-size: small;"> </span> </div>=20 <div> <span style=3D"font-size: small;"><a href=3D"http://www.hopkinsmedicine= .org/news/media/releases/owl_mystery_unraveled_scientists_explain_how_bird_= can_rotate_its_head_without_cutting_off_blood_supply_to_brain"><span style= =3D"color: #0000ff;"><span style=3D"text-decoration: underline;">http://www= .hopkinsmedicine.org/news/media/releases/owl_mystery_unraveled_scientists_e= xplain_how_bird_can_rotate_its_head_without_cutting_off_blood_supply_to_bra= in</span></span></a></span> </div>=20 <div> <span style=3D"font-size: small;"> </span> </div>=20 <div> <span style=3D"font-size: small;"> </span> </div>=20 </div> =20 </body></html>
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