[jQuery] Retrieve function signature from a list

[helveticus]

I have a list of dynamically generated image hyperlinks that are
displayed on a page as follows:

<div class="imgBg">
        <img id="imgProd" src=""  alt=""/>
</div>
<div id="imgEnum">
        <ul>
                <li><span class="sqr1"
                        
onmouseover="updImage('Images/aaa.01.jpg');">1</span></li>
                <li><span class="sqr1" 
onmouseover="updImage('Images/aaa.02.jpg');">
                        2</span></li>
                ...
                <li><span..>N</span></li>
        </ul>
</div>


Problem: This scheme works fine when hovering over the image indexes.
On loading, I would like the first image of the list to be copied to
imgProd via jquery.  How do I extract the mouseover function signature
of the first item ie. "updImage('Images/aaa.01.jpg');" ?

I tried filtering out the li list and narrow it to the first item via
the below code. varImgUR produces the correct signature:
"updImage('/WebHost4Life.Lsite1/Images/Products/Thumbs/
Audree01_md.jpg');"

jQry signature extract code:
jQuery(document).ready(function() {
        // Extract span cnt from first list element
        var sp0 =$("#imgEnum > ul > li span").get(0);
        // Get mouseover fct signature and execute it.
        var sigimgURL =sp0.attributes[0].nodeValue;
        eval(sigimgURL);
});

Function eval()yields the error: "sigimgUrl is not defined"

How can I make this run or alternatively is there a more elegant
jQuery approcach to