JQuery :: Getting Thumbnail Of Next Image In DIV

<ul>
<li><a href="dog.jpg"><img src="dog_t.jpg" alt="dog" /></a></li>
<li><a href="cat.jpg"><img src="cat_t.jpg" alt="cat" /></a></li>
<li><a href="pig.jpg"><img src="pig_t.jpg" alt="pig" /></a></li>
<li><a href="cow.jpg"><img src="cow_t.jpg" alt="cow" /></a></li>
</ul>

My jQuery is set up so that when I click on a thumbnail, a div opens up with the bigger image. I also want the thumbnail of the next image to appear in the same div. So if I click the cat, I want to see the large cat and the pig thumb. How do I tell it that I want the next IMG inside the next A inside the next LI?