McRae line

Changed by Ayla Al Kabbani, 26 Oct 2019

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McRae line is a radiographic line drawn on a lateral skull radiograph or on a midsagittal section of CT or MRI~~, joining~~ that connects the ~~basion~~anterior and ~~~~opisthion~~.~~

~~Normal position~~posterior margins of the ~~tip of dens is 5mm below this line~~foramen magnum (basion to opisthion). ~~If the tip of the dens migrates above this line it~~

Significance

indicates the presence of basilar invagination (atlanto-axial impaction).: the tip of the odontoid process is normally about 5 mm below this line; basilar invagination is diagnosed when the tip crosses this line
helps to measure the cerebellar tonsillar position (TP): normal is above the foramen magnum

-<p><strong>McRae line </strong>is a radiographic line drawn on a lateral skull radiograph or midsagittal section of CT or MRI, joining the <a href="/articles/basion">basion</a> and <a href="/articles/opisthion">opisthion</a>.</p><p>Normal position of the tip of dens is 5mm below this line. If the tip of the dens migrates above this line it indicates the presence of <a href="/articles/basilar-invagination">basilar invagination</a> (atlanto-axial impaction).</p><h4>See also</h4><ul>
+<p><strong>McRae line </strong>is a radiographic line drawn on a lateral skull radiograph or on a midsagittal section of CT or MRI that connects the anterior and posterior margins of the <a href="/articles/foramen-magnum">foramen magnum</a> (<a href="/articles/basion">basion</a> to <a href="/articles/opisthion">opisthion</a>).</p><h5>Significance</h5><ul>
+<li>indicates the presence of <a href="/articles/basilar-invagination">basilar invagination</a> (atlanto-axial impaction): the tip of the odontoid process is normally about 5 mm below this line; basilar invagination is diagnosed when the tip crosses this line</li>
+<li>helps to measure the <a href="/articles/cerebellar-tonsillar-position">cerebellar tonsillar position (TP)</a>: normal is above the <a href="/articles/foramen-magnum">foramen magnum</a>
+</li>
+</ul><h4>See also</h4><ul>