如何从某个键开始迭代多维数组？

我有一个从用户窗体创建的多维数组。我想从循环中的某个键开始，在foreach循环中遍历数组。由于某种原因，我的以下代码无法正常工作。

$i = 3; 

foreach ($data as $val) {
    echo $val[$i] . " : " . $val['value'] . "<br />";
    $i++; 
}

输出：

Array ( 
    [0] => Array ( [name] => name [value] => name ) 
     [1] => Array ( [name] => code [value] => code ) 
    [2] => Array ( [name] => description [value] => description ) 
     [3] => Array ( [name] => unit-1 [value] => uni 1 ) 
     [4] => Array ( [name] => unit-1-section-1 [value] => unit 1 sect 1 ) 
     [5] => Array ( [name] => unit-2 [value] => unit 2 ) 
     [6] => Array ( [name] => unit-2-section-1 [value] => unit 2 section 2 ) 
    ) 

如您所见，我想从$data数组中的第三个键开始。