Restrict position of text node

I have this valid tag:

<Element>
   <SubElement/>
   Some text directly here.
</Element>

But this should not be valid:

<Element>
   Some text directly here.
   <SubElement/>
   Some text directly here.
</Element>

Also this should not be:

<Element>
   <SubElement/>
</Element>

Is there a way to add text nodes to a sequence in XSD?