exibir a foto apenas do usuario logado

QUERIA EXIBIR APENAS A FOTO DO USUARIO_ID QUE LOGAR!!!


/************************BANCO DE DADOS **********************/


CREATE TABLE IF NOT EXISTS `usuario` (
`usuario_id` int(11) NOT NULL,
`nome` varchar(80) NOT NULL,

`foto` varchar(255) NOT NULL,
`email` varchar(80) NOT NULL,

`senha` varchar(80) NOT NULL,
`permissao` int(1) NOT NULL,

`link` varchar(300) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=75 ;






/***********************************HTML*********************************************/
<header class="topo">
<div class="container">
<div class="row">
<div class="span3">
<a href="index.php" title="MCCursos" class="logo">
<img src="img/loja/mccursos4.png"/></a>
</div>
<div class="span9">
<ul class="unstyled pull-right">

<li class="menu">
<a href="cursos.php">
<i class="icon-laptop"></i>
<br>
<span class="tit_menu">Cursos</span>
</a>
</li>
<li class="menu">
<? if(!isset($_SESSION['usuario_id'])){?>

<a href="index.php?mod=cadastro">
<i class="icon-share"></i>
<br>
<span class="tit_menu">Cadastrar</span>
</a>


<li class="menu">
<a href="index.php?mod=login">
<i class="icon-signin"></i>
<br>
<span class="tit_menu">Login</span>
</a>
</li>

<? }else{?>




/****************************************AQUI E O QUE QUERO FAZER ******** PHP *******************************************************/

<?
$sql = mysql_query("SELECT * FROM usuario ORDER BY usuario_id DESC");
if(mysql_num_rows($sql)==true){
while($ln = mysql_fetch_assoc($sql)){
?>

<ul class="dropdown">
<a href="#" class="foto dropdown-toggle" data-toggle="dropdown">

<span class="img">
<img src="<?=URL?>/lib/rdmc.php?src=<?=URL?>/img/loja/<?=$ln['foto']?>&q=70&h=50&w=50" class="img-circle">
</span>
<b class="caret"></b>
</a>
<ul class="dropdown-menu">
<li><a href="#"><i class="icon-cog"></i> Configurações</a></li>
<li role="presentation" class="divider"></li>
<li><a href="modulos/login/funLogin.php?op=sair"><i class="icon-signout"></i> Sair</a></li>
</ul>
</li>
</ul>
</div>
</div>
</div>
</div>
</nav>
<main>

<? }} ?>


desde ja agradeço a todos!!